View source for Allergic rhinitis

{{Short description|Nasal inflammation due to allergens in the air}}
{{Redirect|Hay fever}}{{Use mdy dates|date=September 2024}}{{Infobox medical condition (new)
| name          = Allergic rhinitis
| image         = Misc pollen colorized.jpg
| caption       = SEM Microscope image of [[pollen]] grains from a variety of common plants: sunflower (''[[Helianthus annuus]]''), morning glory (''[[Ipomoea purpurea]]''), prairie hollyhock (''[[Sidalcea malviflora]]''), oriental lily (''[[Lilium auratum]]''), evening primrose (''[[Oenothera fruticosa]]''), and castor bean (''[[Ricinus communis]]'').
| field         = [[Allergy and immunology]]
| synonyms      = Hay fever, pollenosis
| symptoms      = Stuffy itchy nose, [[sneezing]], red, itchy, and watery eyes, swelling around the eyes, itchy ears<ref name=NIH2015Sym/>
| complications = 
| onset         = 20 to 40 years old<ref name=NEJM2015/>
| duration      = 
| types         = 
| causes        = Genetic and environmental factors<ref name=NIH2015Cause/>
| risks         = [[Asthma]], [[allergic conjunctivitis]], [[atopic dermatitis]]<ref name=NEJM2015/>
| diagnosis     = Based on symptoms, [[skin prick test]], blood tests for specific [[antibodies]]<ref name=NIH2015Diag/>
| differential  = [[Common cold]]<ref name=NIH2015Cause/>
| prevention    = Exposure to animals early in life<ref name=NIH2015Cause/>
| treatment     = 
| medication    = Nasal [[corticosteroids|steroids]], [[antihistamine]]s such as [[loratadine]], [[cromolyn sodium]], [[leukotriene receptor antagonists]] such as [[montelukast]], [[allergen immunotherapy]]<ref name=NIH2015Tx/><ref name=NIH2015Imm/>
| prognosis     = 
| frequency     = ~20% (Western countries)<ref name=NEJM2015/><ref name=Dy2010/><br />Approximately 10% to 40% of the global population<ref>{{Cite journal |last1=Siti Sarah |first1=Che Othman |last2=Mohd Ashari |first2=Noor Suryani |date=October 2024 |title=Exploration of Allergic Rhinitis: Epidemiology, Predisposing Factors, Clinical Manifestations, Laboratory Characteristics, and Emerging Pathogenic Mechanisms |journal=Cureus |volume=16 |issue=10 |article-number=e71409 |doi=10.7759/cureus.71409 |doi-access=free |issn=2168-8184 |pmc=11558229 |pmid=39539885}}</ref>
| deaths        = 
}}

<!-- Definition and symptoms -->
'''Allergic rhinitis''', of which the seasonal type is called '''hay fever''', is a type of [[rhinitis|inflammation in the nose]] that occurs when the [[immune system]] overreacts to [[allergen]]s in the air.<ref name="NIH2015Imm">{{cite web|title=Immunotherapy for Environmental Allergies|url=http://www.niaid.nih.gov/topics/environmental-allergies/Pages/immunotherapy.aspx|website=NIAID|access-date=June 19, 2015|date=May 12, 2015|archive-url=https://web.archive.org/web/20150617190743/http://www.niaid.nih.gov/topics/environmental-allergies/Pages/immunotherapy.aspx|archive-date=June 17, 2015}}</ref> It is classified as a [[Allergy|type I hypersensitivity reaction]].<ref>{{Cite web |date=2015-06-17 |title=Types of Allergic Diseases |url=http://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergic-diseases-types.aspx |access-date=2024-11-09 |archive-date=June 17, 2015 |archive-url=https://web.archive.org/web/20150617123632/http://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergic-diseases-types.aspx |url-status=bot: unknown }}</ref> Signs and symptoms include a runny or stuffy nose, [[sneezing]], red, itchy, and watery eyes, and swelling around the eyes.<ref name="NIH2015Sym">{{cite web|title=Environmental Allergies: Symptoms|url=http://www.niaid.nih.gov/topics/environmental-allergies/Pages/symptoms.aspx|website=NIAID|access-date=June 19, 2015|date=April 22, 2015|archive-url=https://web.archive.org/web/20150618023408/http://www.niaid.nih.gov/topics/environmental-allergies/Pages/symptoms.aspx|archive-date=June 18, 2015}}</ref> The fluid from the nose is usually clear.<ref name="NEJM2015" /> Symptom onset is often within minutes following allergen exposure, and can affect sleep and the ability to work or study.<ref name="NEJM2015" /><ref name="Cov2018" /> Some people may develop symptoms only during specific times of the year, often as a result of [[pollen]] exposure.<ref name="NIH2015Cause" /> Many people with allergic rhinitis also have [[asthma]], [[allergic conjunctivitis]], or [[atopic dermatitis]].<ref name="NEJM2015">{{cite journal | vauthors = Wheatley LM, Togias A | title = Clinical practice. Allergic rhinitis | journal = The New England Journal of Medicine | volume = 372 | issue = 5 | pages = 456–63 | date = January 2015 | pmid = 25629743 | pmc = 4324099 | doi = 10.1056/NEJMcp1412282 }}</ref>

<!-- Cause, mechanism, and diagnosis -->
Allergic rhinitis is typically triggered by environmental allergens such as pollen, pet hair, [[Dust mite allergy|dust mites]], or [[mold]].<ref name=NIH2015Cause/> Inherited [[genetics]] and environmental exposures contribute to the development of allergies.<ref name=NIH2015Cause>{{cite web|title=Cause of Environmental Allergies|url=http://www.niaid.nih.gov/topics/environmental-allergies/Pages/cause.aspx|website=NIAID|access-date=June 17, 2015|date=April 22, 2015|archive-url=https://web.archive.org/web/20150617124141/http://www.niaid.nih.gov/topics/environmental-allergies/Pages/cause.aspx|archive-date=June 17, 2015}}</ref> Growing up on a farm and having multiple older siblings are associated with a reduction of this risk.<ref name=NEJM2015/> The underlying mechanism involves [[IgE antibodies]] that attach to an allergen, and subsequently result in the release of inflammatory chemicals such as [[histamine]] from [[mast cells]].<ref name=NEJM2015/> It causes mucous membranes in the nose, eyes and throat to become inflamed and itchy as they work to eject the allergen.<ref>{{Cite web |title=Allergic Rhinitis (Hay Fever): Symptoms, Diagnosis & Treatment |url=https://my.clevelandclinic.org/health/diseases/8622-allergic-rhinitis-hay-fever |access-date=March 23, 2022 |website=Cleveland Clinic |archive-date=March 23, 2022 |archive-url=https://web.archive.org/web/20220323051448/https://my.clevelandclinic.org/health/diseases/8622-allergic-rhinitis-hay-fever |url-status=live }}</ref> Diagnosis is typically based on a combination of [[medical history|symptoms]] and a [[skin prick test]] or blood tests for allergen-specific IgE antibodies.<ref name="NIH2015Diag" /> These tests, however, can give false positives.<ref name=NIH2015Diag>{{cite web|title=Environmental Allergies: Diagnosis|url=http://www.niaid.nih.gov/topics/environmental-allergies/Pages/diagnosis.aspx|website=NIAID|access-date=June 19, 2015|date=May 12, 2015|archive-url=https://web.archive.org/web/20150617185846/http://www.niaid.nih.gov/topics/environmental-allergies/Pages/diagnosis.aspx|archive-date=June 17, 2015}}</ref> The symptoms of allergies resemble those of the [[common cold]]; however, they often last for more than two weeks and, despite the common name, typically do not include a [[fever]].<ref name=NIH2015Cause/>

<!-- Prevention and treatment -->
Exposure to animals early in life might reduce the risk of developing these specific allergies.<ref name=NIH2015Cause/> Several different types of [[Anti-allergic agent|medications]] reduce allergic symptoms, including nasal [[corticosteroids|steroids]], intranasal [[antihistamines]] such as [[olopatadine]] or [[azelastine]], 2nd generation oral antihistamines such as [[loratadine]], [[desloratadine]], [[cetirizine]], or [[fexofenadine]]; the mast cell stabilizer [[cromolyn sodium]], and [[leukotriene receptor antagonists]] such as [[montelukast]].<ref name="Bernstein 2024">{{cite journal |last1=Bernstein |first1=Jonathan A. |last2=Bernstein |first2=Joshua S. |last3=Makol |first3=Richika |last4=Ward |first4=Stephanie |title=Allergic Rhinitis: A Review |journal=JAMA |date=12 March 2024 |volume=331 |issue=10 |pages=866–877 |doi=10.1001/jama.2024.0530|pmid=38470381 }}</ref><ref name=NIH2015Tx>{{cite web|title=Environmental Allergies: Treatments|url=http://www.niaid.nih.gov/topics/environmental-allergies/Pages/treatments.aspx|website=NIAID|access-date=June 17, 2015|date=April 22, 2015|archive-url=https://web.archive.org/web/20150617164725/http://www.niaid.nih.gov/topics/environmental-allergies/Pages/treatments.aspx|archive-date=June 17, 2015}}</ref> Oftentimes, medications do not completely control symptoms, and they may also have side effects.<ref name=NEJM2015/> Exposing people to larger and larger amounts of allergen, known as [[allergen immunotherapy]], is often effective and is used when first line treatments fail to control symptoms.<ref name="NIH2015Imm" /> The allergen can be given as an injection under the skin or as a tablet under the tongue.<ref name=NIH2015Imm/> Treatment typically lasts three to five years, after which benefits may be prolonged.<ref name=NIH2015Imm/>

<!-- Epidemiology and history -->
Allergic rhinitis is the type of [[allergy]] that affects the greatest number of people.<ref name=Fire2002/> In Western countries, between 10 and 30% of people are affected in a given year.<ref name=NEJM2015/><ref name=Dy2010>{{cite journal | vauthors = Dykewicz MS, Hamilos DL | title = Rhinitis and sinusitis | journal = The Journal of Allergy and Clinical Immunology | volume = 125 | issue = 2 Suppl 2 | pages = S103-15 | date = February 2010 | pmid = 20176255 | doi = 10.1016/j.jaci.2009.12.989 }}</ref> It is most common between the ages of twenty and forty.<ref name=NEJM2015/> The first accurate description is from the 10th-century physician [[Abu Bakr al-Razi]].<ref name=Ric2009>{{cite book| vauthors = Colgan R |title=Advice to the young physician on the art of medicine|date=2009|publisher=Springer|location=New York|isbn=978-1-4419-1034-9|page=31|url=https://books.google.com/books?id=DoMVs4HuDAoC&pg=PA31|url-status=live|archive-url=https://web.archive.org/web/20170908181025/https://books.google.com/books?id=DoMVs4HuDAoC&pg=PA31|archive-date=September 8, 2017}}</ref> In 1859, [[Charles Blackley]] identified pollen as the cause.<ref name="BBC2014">{{cite news|author1=Justin Parkinson|title=John Bostock: The man who 'discovered' hay fever|url=https://www.bbc.com/news/magazine-28038630|access-date=June 19, 2015|publisher=BBC News Magazine|date=July 1, 2014|url-status=live|archive-url=https://web.archive.org/web/20150731221944/http://www.bbc.com/news/magazine-28038630|archive-date=July 31, 2015}}</ref> In 1906, the mechanism was determined by [[Clemens von Pirquet]].<ref name=Fire2002>{{cite book|vauthors=Fireman P|title=Pediatric otolaryngology vol 2.|date=2002|publisher=W. B. Saunders|location=Philadelphia, Pa.|isbn=978-99976-198-4-6|page=1065|edition=4th|url=https://books.google.com/books?id=y5rpEdeKtJEC&pg=PA1065|access-date=September 23, 2016|archive-date=July 25, 2020|archive-url=https://web.archive.org/web/20200725033709/https://books.google.com/books?id=y5rpEdeKtJEC&pg=PA1065|url-status=live}}</ref> The link with [[hay]] came about due to an early (and incorrect) theory that the symptoms were brought about by the smell of new hay.<ref name="Lancet1838">{{cite journal|title=Dr. Marshall Hall on Diseases of the Respiratory System; III. Hay Asthma|journal=The Lancet|volume=30|issue=768|date=May 19, 1838|page=245|doi=10.1016/S0140-6736(02)95895-2|url=https://books.google.com/books?id=OBVAAAAAcAAJ&pg=PA245|quote=With respect to what is termed the exciting cause of the disease, since the attention of the public has been turned to the subject an idea has very generally prevailed, that it is produced by the effluvium from new hay, and it has hence obtained the popular name of hay fever. [...] the effluvium from hay has no connection with the disease.|vauthors=Hall M|access-date=September 23, 2016|archive-date=July 25, 2020|archive-url=https://web.archive.org/web/20200725034017/https://books.google.com/books?id=OBVAAAAAcAAJ&pg=PA245|url-status=live|url-access=subscription}}</ref><ref name=Kar2014>{{cite book|title=History of Allergy|date=2014|publisher=Karger Medical and Scientific Publishers|isbn=978-3-318-02195-0|page=62|url=https://books.google.com/books?id=dffSAwAAQBAJ&pg=PA62|url-status=live|archive-url=https://web.archive.org/web/20160610090523/https://books.google.com/books?id=dffSAwAAQBAJ|archive-date=June 10, 2016}}</ref>

==Signs and symptoms==
[[File:Blausen 0015 AllergicRhinitis.png|thumb|Illustration depicting inflammation associated with allergic rhinitis]]
The characteristic symptoms of allergic rhinitis are: [[rhinorrhea]] (excess nasal secretion), [[pruritis|itching]], sneezing fits, and nasal congestion/obstruction.<ref name=AFP10/> Characteristic physical findings include [[conjunctiva]]l swelling and [[erythema]], eyelid swelling with [[Dennie–Morgan fold]]s, lower eyelid venous stasis (rings under the eyes known as "[[allergic shiner]]s"), swollen [[nasal turbinates]], and middle ear effusion.<ref>{{cite journal |vauthors=Valet RS, Fahrenholz JM |title=Allergic rhinitis: update on diagnosis |journal=Consultant |volume=49 |pages=610–3 |year=2009 |url=http://www.consultantlive.com/display/article/10162/1465701 |url-status=live |archive-url=https://web.archive.org/web/20100114135815/http://www.consultantlive.com/display/article/10162/1465701 |archive-date=January 14, 2010 }}</ref> Nasal endoscopy may show findings such as pale and boggy inferior turbinates from mucosal edema, stringy mucus throughout the nasal cavities, and cobblestoning.<ref>{{Cite journal |last1=Ziade |first1=Georges K. |last2=Karami |first2=Reem A. |last3=Fakhri |first3=Ghina B. |last4=Alam |first4=Elie S. |last5=Hamdan |first5=Abdul latif |last6=Mourad |first6=Marc M. |last7=Hadi |first7=Usama M. |date=2016 |title=Reliability assessment of the endoscopic examination in patients with allergic rhinitis |journal=Allergy & Rhinology |volume=7 |issue=3 |pages=e135–e138 |doi=10.2500/ar.2016.7.0176 |issn=2152-6575 |pmc=5244268 |pmid=28107144}}</ref><ref>{{Cite journal |last1=La Mantia |first1=Ignazio |last2=Andaloro |first2=Claudio |date=October 2017 |title=Cobblestone Appearance of the Nasopharyngeal Mucosa |journal=The Eurasian Journal of Medicine |volume=49 |issue=3 |pages=220–221 |doi=10.5152/eurasianjmed.2017.17257 |issn=1308-8734 |pmc=5665636 |pmid=29123450}}</ref>

There can also be behavioral signs; in order to relieve the irritation or flow of mucus, people may wipe or rub their nose with the palm of their hand in an upward motion: an action known as the "'''nasal salute'''" or the "[[allergic salute]]". This may result in a crease running across the nose (or above each nostril if only one side of the nose is wiped at a time), commonly referred to as the "[[transverse nasal crease]]", and can lead to permanent physical deformity if repeated enough.<ref name=pray221>{{cite book| vauthors = Pray WS |title=Nonprescription Product Therapeutics|year=2005|publisher=[[Lippincott Williams & Wilkins]]|page=221|isbn=978-0-7817-3498-1}}</ref>

People might also find that [[oral allergy syndrome|cross-reactivity]] occurs.<ref>{{cite journal | vauthors = Czaja-Bulsa G, Bachórska J | title = [Food allergy in children with pollinosis in the Western sea coast region] | language = Polish | journal = Polski Merkuriusz Lekarski | volume = 5 | issue = 30 | pages = 338–40 | date = December 1998 | pmid = 10101519 | trans-title = Food allergy in children with pollinosis in the Western sea coast region }}</ref> For example, people allergic to birch pollen may also find that they have an allergic reaction to the skin of apples or potatoes.<ref>{{cite journal | vauthors = Yamamoto T, Asakura K, Shirasaki H, Himi T, Ogasawara H, Narita S, Kataura A | title = [Relationship between pollen allergy and oral allergy syndrome] | language = Japanese | journal = Nihon Jibiinkoka Gakkai Kaiho | volume = 108 | issue = 10 | pages = 971–9 | date = October 2005 | pmid = 16285612 | doi = 10.3950/jibiinkoka.108.971 | trans-title = Relationship between Pollen Allergy and Oral Allergy Syndrome | doi-access = free }}</ref> A clear sign of this is the occurrence of an itchy throat after eating an apple or sneezing when peeling potatoes or apples. This occurs because of similarities in the proteins of the pollen and the food.<ref>{{cite journal | vauthors = Malandain H | title = [Allergies associated with both food and pollen] | language = French | journal = European Annals of Allergy and Clinical Immunology | volume = 35 | issue = 7 | pages = 253–6 | date = September 2003 | pmid = 14626714 | trans-title = Allergies associated with both food and pollen | id = {{INIST|15195402}} }}</ref> There are many cross-reacting substances. Hay fever is not a true fever, meaning it does not cause a core body temperature in the fever over {{convert|37.5|–|38.3|C|F}}.{{citation needed|date=March 2023}}

==Cause==
Pollen is often considered as a cause of allergic rhinitis, hence called hay fever (See sub-section below).{{Citation needed|date=November 2024}}

Predisposing factors to allergic rhinitis include eczema (atopic dermatitis) and asthma. These three conditions can often occur together which is referred to as the [[Atopy|atopic triad]].<ref name=":2">{{Cite book|title="Urticaria, Angioedema, and Allergic Rhinitis." 'Harrison's Principles of Internal Medicine | edition = 20th | vauthors = Cahill K | publisher = McGraw-Hill|year=2018|isbn=978-1-259-64403-0|location=NY|pages=Chapter 345}}</ref> Additionally, environmental exposures such as air pollution and maternal tobacco smoking can increase an individual's chances of developing allergies.<ref name=":2" />

===Pollen-related causes===
Allergic rhinitis triggered by the [[pollen]]s of specific seasonal plants is commonly known as "hay fever", because it is most prevalent during [[hay]]ing season. However, it is possible to have allergic rhinitis throughout the year. The pollen that causes hay fever varies between individuals and from region to region; in general, the tiny, hardly visible pollens of [[Anemophily|wind-pollinated]] [[plant]]s are the predominant cause. The study of the dispersion of these [[bioaerosol]]s is called [[Aerobiology]]. Pollens of [[entomophily|insect-pollinated]] plants are too large to remain airborne and pose no risk. Examples of plants commonly responsible for hay fever include:
* Trees: such as pine (''[[Pinus]]''), mulberry (''[[Morus (plant)|Morus]]''), birch (''[[Betula]]''), alder (''[[Alnus]]''), cedar (''[[Cedrus]]''), hazel (''[[Corylus]]''), hornbeam (''[[Carpinus]]''), horse chestnut (''[[Aesculus]]''), willow (''[[Salix]]''), poplar (''[[Populus]]''), plane (''[[Platanus]]''), linden/lime (''[[Tilia]]''), and olive (''[[Olea]]''). In northern latitudes, birch is considered to be the most common allergenic tree pollen, with an estimated 15–20% of people with hay fever sensitive to birch pollen grains. A major antigen in these is a protein called [[Bet v I allergen|Bet V I]]. Olive pollen is most predominant in Mediterranean regions. [[Hay fever in Japan]] is caused primarily by [[sugi]] (''Cryptomeria japonica'') and [[hinoki]] (''Chamaecyparis obtusa'') tree pollen.
** "Allergy friendly" trees include: [[Ash (Fraxinus)|female ash]], red [[maple]], [[yellow poplar]], [[dogwood]], [[magnolia]], [[double-flowered]] [[cherry]], [[fir]], [[spruce]], and flowering [[plum]].<ref>{{cite web |url=http://forestry.about.com/od/difficultissues/a/tree_allergy_3.htm |title=Allergy Friendly Trees |publisher=Forestry.about.com |date=March 5, 2014 |access-date=April 25, 2014 |url-status=live |archive-url=https://web.archive.org/web/20140414124042/http://forestry.about.com/od/difficultissues/a/tree_allergy_3.htm |archive-date=April 14, 2014 }}</ref>
* Grasses (Family [[Poaceae]]): especially ryegrass (''[[Lolium]]'' sp.) and timothy (''[[Phleum pratense]]''). An estimated 90% of people with hay fever are allergic to grass pollen.
* Weeds: [[ragweed]] (''Ambrosia''), plantain (''[[Plantago]]''), nettle/parietaria ([[Urticaceae]]), [[mugwort]] (''Artemisia Vulgaris''), Fat hen (''[[Chenopodium]]''), and sorrel/dock (''[[Rumex]]'')

Allergic rhinitis may also be caused by allergy to [[Balsam of Peru]], which is in various fragrances and other products.<ref name="google1">{{cite book |title=The Daily Telegraph: Complete Guide to Allergies |author=Pamela Brooks |date=2012 |publisher=Little, Brown Book |isbn=978-1-4721-0394-9 }}</ref><ref name="google2">{{cite book |url=https://books.google.com/books?id=dOFXAAAAMAAJ&q=%22balsam+of+peru%22+rhinitis |title=Denver Medical Times: Utah Medical Journal. Nevada Medicine |date=January 1, 2010 |access-date=April 27, 2014 |url-status=live |archive-url=https://web.archive.org/web/20170908181025/https://books.google.com/books?id=dOFXAAAAMAAJ&q=%22balsam+of+peru%22+rhinitis&dq=%22balsam+of+peru%22+rhinitis |archive-date=September 8, 2017 }}</ref><ref name="google3">{{cite book |url=https://books.google.com/books?id=9QBtAAAAMAAJ&q=%22balsam+of+peru%22+rhinitis |title=Diseases of the Skin: For Practitioners and Students |author1=George Clinton Andrews |author2=Anthony Nicholas Domonkos |date=July 1, 1998 |access-date=April 27, 2014 |url-status=live |archive-url=https://web.archive.org/web/20170908181025/https://books.google.com/books?id=9QBtAAAAMAAJ&q=%22balsam+of+peru%22+rhinitis&dq=%22balsam+of+peru%22+rhinitis |archive-date=September 8, 2017 }}</ref>

===Genetic factors===
The causes and pathogenesis of allergic rhinitis are hypothesized to be affected by both genetic and environmental factors, with many recent studies focusing on specific [[Locus (genetics)|loci]] that could be potential [[biological target|therapeutic targets]] for the disease. [[Genome-wide association studies]] (GWAS) have identified a number of different loci and genetic pathways that seem to mediate the body's response to allergens and promote the development of allergic rhinitis, with some of the most promising results coming from studies involving [[single-nucleotide polymorphisms]] (SNPs) in the [[interleukin-33]] (IL-33) gene.<ref name="Kamekura, R., 2012">{{cite journal | vauthors = Kamekura R, Kojima T, Takano K, Go M, Sawada N, Himi T | title = The Role of IL-33 and Its Receptor ST2 in Human Nasal Epithelium with Allergic Rhinitis| journal = Clin Exp Allergy | year = 2012| volume = 42| issue = 2| pages = 218–228| doi =10.1111/j.1365-2222.2011.03867.x| pmid = 22233535| s2cid = 21799632}}</ref><ref name="Liu, Z., 2014">{{cite journal | vauthors = Zhang XH, Zhang YN, Liu Z | title = MicroRNA in Chronic Rhinosinusitis and Allergic Rhinitis| journal = Curr Allergy Asthma Rep | year = 2014| volume = 14| issue = 2| article-number = 415| doi =10.1007/s11882-013-0415-3| pmid = 24408538| s2cid = 39239208}}</ref> The IL-33 protein that is encoded by the IL-33 gene is part of the interleukin family of [[cytokines]] that interact with T-helper 2 (Th2) cells, a specific type of [[T cell]]. Th2 cells contribute to the body's inflammatory response to allergens, with specific ST2 receptors—also known as [[IL1RL1]]—on these cells binding to the ligand IL-33. This IL-33/ST2 signaling pathway has been found to be one of the main genetic determinants in bronchial [[asthma]] pathogenesis, and because of the pathological linkage between asthma and rhinitis, the experimental focus of IL-33 has now turned to its role in the development of allergic rhinitis in humans and mouse [[Model organism|models]].<ref name="Baumann, R., 2013">{{cite journal | vauthors = Baumann R, Rabaszowski M, Stenin I, Tilgner L, Gaertner-Akerboom M, Scheckenbach K, Wiltfang J, Chaker A, Schipper J, Wagenmann M | title = Nasal Levels of Soluble IL-33R ST2 and IL-16 in Allergic Rhinitis: Inverse Correlation Trends with Disease Severity| journal = Clin Exp Allergy | year = 2013| volume = 43| issue = 10| pages = 1134–1143| doi =10.1111/cea.12148| pmid = 24074331| s2cid = 32689683}}</ref> Recently, it was found that allergic rhinitis patients expressed higher levels of IL-33 in their nasal [[epithelium]] and had a higher concentration of ST2 serum in nasal passageways following their exposure to pollen and other allergens, indicating that this gene and its associated receptor are expressed at a higher rate in allergic rhinitis patients.<ref name="Ran, H., 2020">{{cite journal | vauthors = Ran H, Xiao H, Zhou X, Guo L, Lu S | title = Single-Nucleotide Polymorphisms and Haplotypes in the Interleukin-33 Gene Are Associated with a Risk of Allergic Rhinitis in the Chinese Population| journal = Exp Ther Med| year = 2020| volume = 20| issue = 5| page = 102| doi =10.3892/etm.2020.9232| pmid = 32973951| pmc = 7506885}}</ref> In a 2020 study on [[Polymorphism (biology)|polymorphisms]] of the IL-33 gene and their link to allergic rhinitis within the Han Chinese population, researchers found that five SNPs specifically contributed to the pathogenesis of allergic rhinitis, with three of those five SNPs previously identified as genetic determinants for asthma.<ref>{{Cite journal|last1=Ran|first1=He|last2=Xiao|first2=Hua|last3=Zhou|first3=Xing|last4=Guo|first4=Lijun|last5=Lu|first5=Shuang|date=November 2020|title=Single-nucleotide polymorphisms and haplotypes in the interleukin-33 gene are associated with a risk of allergic rhinitis in the Chinese population|journal=Experimental and Therapeutic Medicine|volume=20|issue=5|page=102|doi=10.3892/etm.2020.9232|issn=1792-0981|pmc=7506885|pmid=32973951}}</ref>

Another study focusing on Han Chinese children found that certain SNPs in the protein tyrosine phosphatase non-receptor 22 ([[PTPN22]]) gene and cytotoxic T-lymphocyte-associated antigen 4 ([[CTLA-4]]) gene can be associated with childhood allergic rhinitis and allergic asthma.<ref name="Song, S. H., 2016">{{cite journal | vauthors = Song SH, Wang XQ, Shen Y, Hong SL, Ke, X | title = Association between PTPN22/CTLA-4 Gene Polymorphism and Allergic Rhinitis with Asthma in Children| journal = Iranian Journal of Allergy, Asthma and Immunology| volume = | issue = | pages = 413–419| doi = }}</ref> The encoded PTPN22 protein, which is found primarily in [[lymphoid]] tissue, acts as a [[post-translational]] regulator by removing phosphate groups from targeted proteins. Importantly, PTPN22 can affect the [[phosphorylation]] of T cell responses, and thus the subsequent [[Cell proliferation|proliferation]] of the T cells. As mentioned earlier, T cells contribute to the body's inflammatory response in a variety of ways, so any changes to the cells' structure and function can have potentially deleterious effects on the body's inflammatory response to allergens. To date, one SNP in the PTPN22 gene has been found to be significantly associated with allergic rhinitis onset in children. On the other hand, CTLA-4 is an immune-checkpoint protein that helps mediate and control the body's immune response to prevent overactivation. It is expressed only in T cells as a [[glycoprotein]] for the [[Immunoglobulin]] (Ig) [[protein family]], also known as [[antibodies]]. There have been two SNPs in CTLA-4 that were found to be significantly associated with childhood allergic rhinitis. Both SNPs most likely affect the associated protein's shape and function, causing the body to exhibit an overactive immune response to the posed allergen. The polymorphisms in both genes are only beginning to be examined, therefore more research is needed to determine the severity of the impact of polymorphisms in the respective genes.{{citation needed|date=July 2022}}

Finally, [[epigenetic]] alterations and associations are of particular interest to the study and ultimate treatment of allergic rhinitis. Specifically, [[microRNAs]] (miRNA) are hypothesized to be imperative to the pathogenesis of allergic rhinitis due to the [[post-transcriptional regulation]] and repression of translation in their mRNA complement. Both miRNAs and their common carrier vessel [[Exosome (vesicle)|exosomes]] have been found to play a role in the body's immune and inflammatory responses to allergens. miRNAs are housed and packaged inside of exosomes until they are ready to be released into the section of the cell that they are coded to reside and act. Repressing the translation of proteins can ultimately repress parts of the body's immune and inflammatory responses, thus contributing to the pathogenesis of allergic rhinitis and other autoimmune disorders. There are many miRNAs that have been deemed potential therapeutic targets for the treatment of allergic rhinitis by many different researchers, with the most widely studied being miR-133, miR-155, miR-205, miR-498, and let-7e.<ref name="Liu, Z., 2014"/><ref name="Suojalehto, H., 2013">{{cite journal | vauthors = Suojalehto H, Toskala E, Kilpeläinen M, Majuri ML, Mitts C, Lindström I, Puustinen A, Plosila T, Sipilä J, Wolff H, Alenius H | title = MicroRNA Profiles in Nasal Mucosa of Patients with Allergic and Nonallergic Rhinitis and Asthma.| journal = International Forum of Allergy and Rhinology | year = 2013| volume = 3| issue = 8| pages = 612–620| doi =10.1002/alr.21179| pmid = 23704072| s2cid = 29759402}}</ref><ref name="Sastre, B., 2017">{{cite journal | vauthors = Sastre B, Cañas JA, Rodrigo-Muñoz JM, del Pozo V | title = Novel Modulators of Asthma and Allergy: Exosomes and MicroRNAs.| journal = Front Immunol | year = 2017| volume = 8| issue = | page = 826| doi =10.3389/fimmu.2017.00826| pmid = 28785260| pmc = 5519536| doi-access = free}}</ref><ref name="Xiao, L., 2017">{{cite journal | vauthors = Xiao L, Jiang L, Hu Q, Li Y | title = MicroRNA-133b Ameliorates Allergic Inflammation and Symptom in Murine Model of Allergic Rhinitis by Targeting NIrp3| journal = CPB | volume = 42| issue = 3| pages = 901–912| doi =}}</ref>

=== Air pollution ===
Numerous studies confirm that ambient air pollution particularly traffic-related pollutants like [[nitrogen dioxide]] (NO<sub>2</sub>), [[carbon monoxide]] (CO), [[sulfur dioxide]] (SO<sub>2</sub>), and [[fine particulate matter]] (PM<sub>2.5</sub> and PM<sub>10</sub>) is significantly associated with both the prevalence and severity of allergic rhinitis. One [[Taiwan|Taiwanese]] study found that a 10 ppb increase in NO<sub>x</sub> corresponded to an 11% higher odds of physician‑diagnosed allergic rhinitis, with smaller yet significant associations for CO, SO<sub>2</sub>, and PM<sub>10</sub>.<ref>{{Cite journal |last1=Hwang |first1=Bing-Fang |last2=Jaakkola |first2=Jouni JK |last3=Lee |first3=Yung-Ling |last4=Lin |first4=Ying-Chu |last5=Leon Guo |first5=Yue-liang |date=2006-02-09 |title=Relation between air pollution and allergic rhinitis in Taiwanese schoolchildren |journal=Respiratory Research |volume=7 |issue=1 |page=23 |doi=10.1186/1465-9921-7-23 |pmid=16469096 |pmc=1420289 |doi-access=free |issn=1465-993X}}</ref> Chinese meta-analysis data echoed this trend: increases in SO<sub>2</sub> (OR ≈ 1.03), NO<sub>2</sub> (OR ≈ 1.11), PM<sub>10</sub> (OR ≈ 1.02), and PM<sub>2.5</sub> (OR ≈ 1.15) all correlated with heightened risk of childhood allergic rhinitis, while ozone exposure showed no significant association.<ref>{{Cite journal |last1=Zhang |first1=Shipeng |last2=Fu |first2=Qinwei |last3=Wang |first3=Shuting |last4=Jin |first4=Xin |last5=Tan |first5=Junwen |last6=Ding |first6=Kaixi |last7=Zhang |first7=Qinxiu |last8=Li |first8=Xinrong |date=2022-09-01 |title=Association between air pollution and the prevalence of allergic rhinitis in Chinese children: A systematic review and meta-analysis |journal=Allergy and Asthma Proceedings |volume=43 |issue=5 |pages=e47–e57 |doi=10.2500/aap.2022.43.220044 |issn=1539-6304 |pmid=36065105}}</ref> 

Air pollutants impair the respiratory epithelial barrier, increasing permeability and inflammation. This occurs through mechanisms such as [[oxidative stress]], immune modulation, and epigenetic changes. [[Diesel engine|Diesel]] exhaust particles (DEP), for example, have been shown to enhance allergic inflammation by boosting eosinophil activation when allergens are present. Meanwhile, damaged nasal mucosa facilitates deeper allergen penetration, intensifying rhinitis symptoms.<ref>{{Cite journal |last1=Kanjanawasee |first1=Dichapong |last2=Limjunyawong |first2=Nathachit |last3=Tantilipikorn |first3=Pongsakorn |date=2025-07-03 |title=Role of air pollution in rhinitis |url=https://www.explorationpub.com/Journals/eaa/Article/100985?utm_source=chatgpt.com |journal=Exploration of Asthma & Allergy |language=en |volume=3 |article-number=100985 |doi=10.37349/eaa.2025.100985 |issn=2837-5076|doi-access=free }}</ref> Urbanization, vehicle emissions, and fossil fuel combustion have accelerated in recent decades, coinciding with a steady rise in allergic rhinitis prevalence. For instance, in Southeast Asia and parts of Latin America, higher AR rates align strongly with poorer air quality.<ref>{{Cite journal |last1=Rosario Filho |first1=Nelson A. |last2=Satoris |first2=Rogério Aranha |last3=Scala |first3=Wanessa Ruiz |date=August 2021 |title=Allergic rhinitis aggravated by air pollutants in Latin America: A systematic review |journal=The World Allergy Organization Journal |volume=14 |issue=8 |article-number=100574 |doi=10.1016/j.waojou.2021.100574 |issn=1939-4551 |pmc=8387759 |pmid=34471459}}</ref>

==Pathophysiology==
The pathophysiology of allergic rhinitis involves [[Helper T cell|Th2 Helper T cell]] and [[IgE]] mediated inflammation with overactive function of the adaptive and innate immune systems.<ref name="Bernstein 2024" /> The process begins when an aeroallergen penetrates the [[nasal mucosa|nasal mucosal barrier]]. This barrier may be more permeable in susceptible individuals. The allergen is then engulfed by an [[antigen presenting cell]] (APC) (such as a [[dendritic cell]]).<ref name="Bernstein 2024" /> The APC then presents the antigen to a Naive CD4+ helper T cell stimulating it to differentiate into a Th2 helper T cell. The Th2 helper T cell then secretes inflammatory cytokines including [[Interleukin 4|IL-4]], [[Interleukin 5|IL-5]], [[Interleukin 13|IL-13]], [[Interleukin 14|IL-14]], and [[Interleukin 31|IL-31]]. These inflammatory cytokines stimulate [[B cells]] to differentiate into [[plasma cells]] and release allergen specific IgE immunoglobulins.<ref name="Bernstein 2024" /> The IgE immunoglobulins attach to [[mast cells]]. The inflammatory cytokines also recruit inflammatory cells such as [[basophils]], [[eosinophils]] and [[fibroblasts]] to the area.<ref name="Bernstein 2024" /> The person is now sensitized, and upon re-exposure to the allergen, mast cells with allergen specific IgE will bind the allergens and release inflammatory molecules including [[histamine]], [[leukotrienes]], [[platelet activating factor]], [[prostaglandins]] and [[thromboxane]] with these inflammatory molecules' local effects on blood vessels (dilation), mucous glands (secrete mucous) and sensory nerves (activation) leading to the clinical signs and symptoms of allergic rhinitis.<ref name="Bernstein 2024" />

Disruption of the nasal mucosal epithelial barrier may also release alarmins (a type of [[damage associated molecular pattern]] (DAMP) molecule) such as [[thymic stromal lymphopoietin]], [[interleukin 25|IL-25]] and [[interleukin 33|IL-33]] which activate group 2 innate lymphoid cells ([[ILC2]]) which then also releases inflammatory cytokines leading to activation of immune cells.<ref name="Bernstein 2024" />

==Diagnosis==
[[File:Epikutanni-test.jpg|thumb|upright=1.3|[[Patch test]]]]
Allergy testing may reveal the specific allergens to which an individual is sensitive. Skin testing is the most common method of allergy testing.<ref name=":1" /> {{Failed verification|date=September 2024}} This may include a [[patch test]] to determine if a particular substance is causing the rhinitis, or an intradermal, scratch, or other test. Less commonly, the suspected allergen is dissolved and dropped onto the lower eyelid as a means of testing for allergies. This test should be done only by a physician, since it can be harmful if done improperly. In some individuals not able to undergo skin testing (as determined by the doctor), the [[RAST blood test]] may be helpful in determining specific allergen sensitivity. Peripheral [[eosinophilia]] can be seen in differential leukocyte count.{{citation needed|date=July 2022}}

Allergy testing is not definitive. At times, these tests can reveal positive results for certain allergens that are not actually causing symptoms, and can also not pick up allergens that do cause an individual's symptoms. The intradermal allergy test is more sensitive than the skin prick test, but is also more often positive in people that do not have symptoms to that allergen.<ref>{{cite web | url=http://www.webmd.com/allergies/allergy-tests | title=Allergy Tests | work=WebMD | url-status=live | archive-url=https://web.archive.org/web/20120114062313/http://www.webmd.com/allergies/allergy-tests | archive-date=January 14, 2012 }}</ref>

Even if a person has negative [[skin allergy test|skin-prick, intradermal]] and [[RAST test|blood tests]] for allergies, they may still have allergic rhinitis, from a local allergy in the nose. This is called [[#Local allergic rhinitis|local allergic rhinitis]].<ref name="lar0">{{cite journal | vauthors = Rondón C, Canto G, Blanca M | title = Local allergic rhinitis: a new entity, characterization and further studies | journal = Current Opinion in Allergy and Clinical Immunology | volume = 10 | issue = 1 | pages = 1–7 | date = February 2010 | pmid = 20010094 | doi = 10.1097/ACI.0b013e328334f5fb | s2cid = 3472235 }}</ref> Specialized testing is necessary to diagnose local allergic rhinitis.<ref name="lar">{{cite journal | vauthors = Rondón C, Fernandez J, Canto G, Blanca M | title = Local allergic rhinitis: concept, clinical manifestations, and diagnostic approach | journal = Journal of Investigational Allergology & Clinical Immunology | volume = 20 | issue = 5 | pages = 364–71; quiz 2 p following 371 | date = 2010 | pmid = 20945601 | url = http://www.jiaci.org/issues/vol20issue5/vol20issue05-1.htm | access-date = December 27, 2020 | archive-date = February 2, 2022 | archive-url = https://web.archive.org/web/20220202174727/http://www.jiaci.org/issues/vol20issue5/vol20issue05-1.htm | url-status = live }}</ref>

===Classification===
* '''Seasonal allergic rhinitis''' ('''hay fever'''): Caused by seasonal peaks in the airborne load of pollens.
* '''Perennial allergic rhinitis''' ('''nonseasonal allergic rhinitis'''; '''atopic rhinitis'''): Caused by allergens present throughout the year (e.g., dander).

Allergic rhinitis may be seasonal, perennial, or episodic.<ref name="Cov2018">{{Cite book|chapter=Allergic Disorders |title=Current Diagnosis & Treatment: Pediatrics |edition=24th | vauthors = Covar R |publisher=McGraw-Hill |year=2018 |isbn=978-1-259-86290-8 |location=NY }}</ref>  Seasonal allergic rhinitis occurs in particular during pollen seasons. It does not usually develop until after 6 years of age. Perennial allergic rhinitis occurs throughout the year. This type of allergic rhinitis is commonly seen in younger children.<ref>{{cite web|url=https://www.rush.edu/health-wellness/discover-health/pollen-food-allergy-syndrome|title=Rush University Medical Center|access-date=March 5, 2008|url-status=live|archive-url=https://web.archive.org/web/20150219015114/https://www.rush.edu/health-wellness/discover-health/pollen-food-allergy-syndrome|archive-date=February 19, 2015}}</ref>

Allergic rhinitis may also be classified as mild-intermittent, moderate-severe intermittent, mild-persistent, and moderate-severe persistent. Intermittent is when the symptoms occur <4 days per week or <4 consecutive weeks. Persistent is when symptoms occur >4 days/week and >4 consecutive weeks. The symptoms are considered mild with normal sleep, no impairment of daily activities, no impairment of work or school, and if symptoms are not troublesome. Severe symptoms result in sleep disturbance, impairment of daily activities, and impairment of school or work.<ref>{{cite journal | vauthors = Bousquet J, Reid J, van Weel C, Baena Cagnani C, Canonica GW, Demoly P, Denburg J, Fokkens WJ, Grouse L, Mullol K, Ohta K, Schermer T, Valovirta E, Zhong N, Zuberbier T | display-authors = 6 | title = Allergic rhinitis management pocket reference 2008 | journal = Allergy | volume = 63 | issue = 8 | pages = 990–6 | date = August 2008 | pmid = 18691301 | doi = 10.1111/j.1398-9995.2008.01642.x | s2cid = 11933433 | doi-access = free }}</ref>

===Local allergic rhinitis===
Local allergic rhinitis is an allergic reaction in the nose to an allergen, without systemic allergies. So [[skin allergy test|skin-prick]] and [[RAST test|blood tests]] for allergy are negative, but there are [[immunoglobulin E|IgE]] antibodies produced in the nose that react to a specific [[allergen]]. [[skin allergy test|Intradermal skin testing]] may also be negative.<ref name="lar"/>

The symptoms of local allergic rhinitis are the same as the symptoms of allergic rhinitis, including symptoms in the eyes. Just as with allergic rhinitis, people can have either seasonal or perennial local allergic rhinitis. The symptoms of local allergic rhinitis can be mild, moderate, or severe. Local allergic rhinitis is associated with [[allergic conjunctivitis|conjunctivitis]] and [[asthma]].<ref name="lar"/>

In one study, about 25% of people with rhinitis had local allergic rhinitis.<ref>{{cite journal | vauthors = Rondón C, Campo P, Galindo L, Blanca-López N, Cassinello MS, Rodriguez-Bada JL, Torres MJ, Blanca M | display-authors = 6 | title = Prevalence and clinical relevance of local allergic rhinitis | journal = Allergy | volume = 67 | issue = 10 | pages = 1282–8 | date = October 2012 | pmid = 22913574 | doi = 10.1111/all.12002 | s2cid = 22470654 }}</ref> In several studies, over 40% of people having been diagnosed with [[nonallergic rhinitis]] were found to actually have local allergic rhinitis.<ref name="lar0"/> Steroid nasal sprays and oral antihistamines have been found to be effective for local allergic rhinitis.<ref name="lar"/>

As of 2014, local allergenic rhinitis had mostly been investigated in Europe; in the United States, the nasal provocation testing necessary to diagnose the condition was not widely available.<ref>{{Cite book|url=https://books.google.com/books?id=lFajBQAAQBAJ|title=Cummings Otolaryngology–Head and Neck Surgery E-Book|vauthors=Flint PW, Haughey BH, Robbins KT, Thomas JR, Niparko JK, Lund VJ, Lesperance MM|date=November 28, 2014|publisher=Elsevier Health Sciences|isbn=978-0-323-27820-1|language=en|access-date=April 20, 2019|archive-date=July 25, 2020|archive-url=https://web.archive.org/web/20200725035636/https://books.google.com/books?id=lFajBQAAQBAJ|url-status=live}}</ref>{{Rp|617}}

==Prevention==
Prevention often focuses on avoiding specific allergens that cause an individual's symptoms. These methods include not having pets, not having carpets or upholstered furniture in the home, and keeping the home dry.<ref>{{cite web |title=Prevention |url=https://www.nhs.uk/conditions/allergic-rhinitis/prevention/ |website=nhs.uk |access-date=February 17, 2019 |language=en |date=October 3, 2018 |archive-date=February 18, 2019 |archive-url=https://web.archive.org/web/20190218021529/https://www.nhs.uk/conditions/allergic-rhinitis/prevention/ |url-status=live }}</ref> Specific anti-allergy zippered covers on household items like pillows and mattresses have also proven to be effective in preventing dust mite allergies.<ref name=":1" />

Studies have shown that growing up on a farm and having many older siblings are associated with a reduction in individual's risk for developing allergic rhinitis.<ref name="NEJM2015" />

Studies in young children have shown that there is higher risk of allergic rhinitis in those who have early exposure to foods or formula or heavy exposure to cigarette smoking within the first year of life.<ref>Akhouri S, House SA. Allergic Rhinitis. [Updated 2020 Nov 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538186/ {{Webarchive|url=https://web.archive.org/web/20220318111923/https://www.ncbi.nlm.nih.gov/books/NBK538186/ |date=March 18, 2022 }}</ref><ref>{{cite journal | vauthors = Skoner DP | title = Allergic rhinitis: definition, epidemiology, pathophysiology, detection, and diagnosis | journal = The Journal of Allergy and Clinical Immunology | volume = 108 | issue = 1 Suppl | pages = S2-8 | date = July 2001 | pmid = 11449200 | doi = 10.1067/mai.2001.115569 | doi-access = free }}</ref>

==Treatment==
The goal of rhinitis treatment is to prevent or reduce the symptoms caused by the inflammation of affected tissues. Measures that are effective include avoiding the allergen.<ref name=AFP10>{{cite journal | vauthors = Sur DK, Plesa ML | title = Treatment of Allergic Rhinitis | journal = American Family Physician | volume = 92 | issue = 11 | pages = 985–92 | date = December 2015 | pmid = 26760413 | url = https://www.aafp.org/afp/2015/1201/p985.html | access-date = April 21, 2018 | archive-date = April 22, 2018 | archive-url = https://web.archive.org/web/20180422063038/https://www.aafp.org/afp/2015/1201/p985.html | url-status = live }}</ref> Intranasal [[corticosteroid]]s (eg, [[flunisolide]]) are the preferred medical treatment for persistent symptoms, with other options if this is not effective.<ref name=AFP10/> Second line therapies include [[antihistamines]], [[decongestants]], [[cromolyn]], [[leukotriene receptor antagonists]], and [[nasal irrigation]].<ref name=AFP10/> Antihistamines by mouth are suitable for occasional use with mild intermittent symptoms.<ref name=AFP10/> [[Mite]]-proof covers, air filters, and withholding certain foods in childhood do not have evidence supporting their effectiveness.<ref name=AFP10/>

===Antihistamines===
[[Antihistamine]] drugs can be taken orally and nasally to control symptoms such as sneezing, rhinorrhea, itching, and conjunctivitis.<ref>{{Cite web |title=Antihistamines for Allergies |url=https://medlineplus.gov/ency/patientinstructions/000549.htm |access-date=March 18, 2023 |website=MedlinePlus.gov |archive-date=March 19, 2023 |archive-url=https://web.archive.org/web/20230319000641/https://medlineplus.gov/ency/patientinstructions/000549.htm |url-status=live }}</ref>

It is best to take oral antihistamine medication before exposure, especially for seasonal allergic rhinitis. In the case of nasal antihistamines like [[azelastine|azelastine antihistamine nasal spray]], relief from symptoms is experienced within 15 minutes allowing for a more immediate 'as-needed' approach to dosage. There is not enough evidence of antihistamine efficacy as an add-on therapy with nasal steroids in the management of intermittent or persistent allergic rhinitis in children, so its adverse effects and additional costs must be considered.<ref>{{cite journal | vauthors = Nasser M, Fedorowicz Z, Aljufairi H, McKerrow W | title = Antihistamines used in addition to topical nasal steroids for intermittent and persistent allergic rhinitis in children | journal = The Cochrane Database of Systematic Reviews | issue = 7 | article-number = CD006989 | date = July 2010 | volume = 2010 | pmid = 20614452 | pmc = 7388927 | doi = 10.1002/14651858.CD006989.pub2 }}</ref>

Ophthalmic antihistamines (such as [[Azelastine#Azelastine eye drops|azelastine in eye drop form]] and [[ketotifen]]) are used for conjunctivitis, while intranasal forms are used mainly for sneezing, rhinorrhea, and nasal pruritus.<ref name=Dipiro08/>

Antihistamine drugs can have undesirable side-effects, the most notable one being [[drowsiness]] in the case of oral antihistamine tablets. [[First-generation antihistamine|First-generation antihistamine drugs]] such as [[diphenhydramine]] cause drowsiness, while [[Second-generation antihistamine|second- and third-generation antihistamines]] such as [[fexofenadine]] and [[loratadine]] are less likely to.<ref name=Dipiro08/><ref>{{Citation |last1=Craun |first1=Kari L. |title=Fexofenadine |date=2024 |work=StatPearls |url=https://www.ncbi.nlm.nih.gov/books/NBK556104/#:~:text=%5B9%5D%5B10%5D%20Compared,results%20in%20minimal%20anticholinergic%20effects. |access-date=August 16, 2024 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32310564 |last2=Patel |first2=Preeti |last3=Schury |first3=Mark P.}}</ref>

[[Pseudoephedrine]] is also indicated for vasomotor rhinitis. It is used only when nasal congestion is present and can be used with antihistamines. In the United States, oral decongestants containing pseudoephedrine must be purchased behind the pharmacy counter in an effort to prevent the manufacturing of methamphetamine.<ref name=Dipiro08>{{cite book | vauthors = May JR, Smith PH |chapter=Allergic Rhinitis | veditors = DiPiro JT, Talbert RL, Yee GC, Matzke G, Wells B, Posey LM |title=Pharmacotherapy: A Pathophysiologic Approach |publisher=McGraw-Hill |location=New York |year=2008 |isbn=978-0-07-147899-1 |pages=1565–75 |edition=7th}}</ref> [[Desloratadine/pseudoephedrine]] can also be used for this condition{{citation needed|date=March 2020}}

===Steroids===

[[Intranasal]] corticosteroids are used to control symptoms associated with sneezing, rhinorrhea, itching, and nasal congestion.<ref name=":2" /> Steroid [[nasal spray]]s are effective and safe, and may be effective without oral antihistamines. They take several days to act and so must be taken continually for several weeks, as their therapeutic effect builds up with time.{{citation needed|date=July 2022}}

In 2013, a study compared the efficacy of [[Mometasone|mometasone furoate]] nasal spray to [[betamethasone]] oral tablets for the treatment of people with seasonal allergic rhinitis and found that the two have virtually equivalent effects on nasal symptoms in people.<ref>{{cite journal | vauthors = Karaki M, Akiyama K, Mori N | title = Efficacy of intranasal steroid spray (mometasone furoate) on treatment of patients with seasonal allergic rhinitis: comparison with oral corticosteroids | journal = Auris, Nasus, Larynx | volume = 40 | issue = 3 | pages = 277–81 | date = June 2013 | pmid = 23127728 | doi = 10.1016/j.anl.2012.09.004 }}</ref>

Systemic [[steroids]] such as [[prednisone]] tablets and intramuscular [[triamcinolone acetonide]] or [[glucocorticoid]] (such as [[betamethasone]]) injection are effective at reducing nasal inflammation, {{citation needed|date=May 2015}} but their use is limited by their short duration of effect and the side-effects of prolonged steroid therapy.<ref>{{cite journal | vauthors = Ohlander BO, Hansson RE, Karlsson KE | title = A comparison of three injectable corticosteroids for the treatment of patients with seasonal hay fever | journal = The Journal of International Medical Research | volume = 8 | issue = 1 | pages = 63–9 | year = 1980 | pmid = 7358206 | doi = 10.1177/030006058000800111 | s2cid = 24169670 }}</ref>

===Others===
Other measures that may be used second line include: [[decongestant]]s, [[cromolyn]], [[leukotriene receptor antagonist]]s, and nonpharmacologic therapies such as [[nasal irrigation]].<ref name=AFP10/>

[[Topical decongestant]]s may also be helpful in reducing symptoms such as nasal congestion, but should not be used for long periods, as stopping them after protracted use can lead to a rebound nasal congestion called [[rhinitis medicamentosa]].{{citation needed|date=July 2022}}

For nocturnal symptoms, intranasal [[corticosteroid]]s can be combined with nightly [[oxymetazoline]], an [[adrenergic alpha-agonist]], [[Azelastine|or an antihistamine nasal spray]] without risk of rhinitis medicamentosa.<ref name="pmid21377716">{{cite journal | vauthors = Baroody FM, Brown D, Gavanescu L, DeTineo M, Naclerio RM | title = Oxymetazoline adds to the effectiveness of fluticasone furoate in the treatment of perennial allergic rhinitis | journal = The Journal of Allergy and Clinical Immunology | volume = 127 | issue = 4 | pages = 927–34 | date = April 2011 | pmid = 21377716 | doi = 10.1016/j.jaci.2011.01.037 | doi-access = free }}</ref>

Nasal saline irrigation (a practice where salt water is poured into the nostrils), may have benefits in both adults and children in relieving the symptoms of allergic rhinitis and it is unlikely to be associated with adverse effects.<ref>{{cite journal | vauthors = Head K, Snidvongs K, Glew S, Scadding G, Schilder AG, Philpott C, Hopkins C | title = Saline irrigation for allergic rhinitis | journal = The Cochrane Database of Systematic Reviews | volume = 2018 | article-number = CD012597 | date = June 2018 | issue = 6 | pmid = 29932206 | pmc = 6513421 | doi = 10.1002/14651858.CD012597.pub2 }}</ref>

===Allergen immunotherapy===
Allergen immunotherapy, also called desensitization, treatment involves administering doses of allergens to accustom the body to substances that are generally harmless (pollen, [[house dust mites]]), thereby inducing specific long-term tolerance.<ref>{{cite journal | vauthors = Van Overtvelt L, Batard T, Fadel R, Moingeon P |title=Mécanismes immunologiques de l'immunothérapie sublinguale spécifique des allergènes |journal=Revue Française d'Allergologie et d'Immunologie Clinique |date=December 2006 |volume=46 |issue=8 |pages=713–720 |doi=10.1016/j.allerg.2006.10.006 }}</ref> Allergen immunotherapy is the only treatment that alters the disease mechanism.<ref>{{Cite web|url=https://www.uptodate.com/contents/subcutaneous-immunotherapy-for-allergic-disease-indications-and-efficacy|title=Subcutaneous immunotherapy for allergic disease: Indications and efficacy|vauthors=Creticos P|website=UpToDate|access-date=December 2, 2019|archive-date=July 25, 2020|archive-url=https://web.archive.org/web/20200725033355/https://www.uptodate.com/contents/subcutaneous-immunotherapy-for-allergic-disease-indications-and-efficacy?search=allergic%20rhinitis&usage_type=default&source=search_result&selectedTitle=10~150&display_rank=10|url-status=live}}</ref> Immunotherapy can be administered orally (as sublingual tablets or sublingual drops), or by injections under the skin (subcutaneous). Subcutaneous immunotherapy is the most common form and has the largest body of evidence supporting its effectiveness.<ref>{{cite journal | vauthors = Calderon MA, Alves B, Jacobson M, Hurwitz B, Sheikh A, Durham S | title = Allergen injection immunotherapy for seasonal allergic rhinitis | journal = The Cochrane Database of Systematic Reviews | issue = 1 | article-number = CD001936 | date = January 2007 | volume = 2007 | pmid = 17253469 | pmc = 7017974 | doi = 10.1002/14651858.CD001936.pub2 }}</ref>

===Alternative medicine===
There are no forms of complementary or alternative medicine that are evidence-based for allergic rhinitis.<ref name=":1">{{Cite web|url=https://www.aaaai.org/conditions-and-treatments/conditions-dictionary/complementary-and-alternative-medicines|title=American Academy of Allergy Asthma and Immunology|access-date=November 25, 2019|archive-date=July 25, 2020|archive-url=https://web.archive.org/web/20200725031712/https://www.aaaai.org/conditions-and-treatments/conditions-dictionary/complementary-and-alternative-medicines|url-status=live}}</ref> Therapeutic efficacy of alternative treatments such as [[acupuncture]] and [[homeopathy]] is not supported by available evidence.<ref>{{cite journal | vauthors = Passalacqua G, Bousquet PJ, Carlsen KH, Kemp J, Lockey RF, Niggemann B, Pawankar R, Price D, Bousquet J | display-authors = 6 | title = ARIA update: I—Systematic review of complementary and alternative medicine for rhinitis and asthma | journal = The Journal of Allergy and Clinical Immunology | volume = 117 | issue = 5 | pages = 1054–62 | date = May 2006 | pmid = 16675332 | doi = 10.1016/j.jaci.2005.12.1308 }}</ref><ref>{{cite journal | vauthors = Terr AI | title = Unproven and controversial forms of immunotherapy | journal = Clinical Allergy and Immunology | volume = 18 | pages = 703–10 | date = 2004 | pmid = 15042943 }}</ref> While some evidence shows that acupuncture is effective for rhinitis, specifically targeting the [[sphenopalatine ganglion]] acupoint, these trials are still limited.<ref>{{cite journal | vauthors = Fu Q, Zhang L, Liu Y, Li X, Yang Y, Dai M, Zhang Q | title = Effectiveness of Acupuncturing at the Sphenopalatine Ganglion Acupoint Alone for Treatment of Allergic Rhinitis: A Systematic Review and Meta-Analysis | journal = Evidence-Based Complementary and Alternative Medicine | volume = 2019 | article-number = 6478102 | date = March 12, 2019 | pmid = 30992709 | pmc = 6434301 | doi = 10.1155/2019/6478102 | doi-access = free }}</ref> Overall, the quality of evidence for complementary-alternative medicine is not strong enough to be recommended by the [[American Academy of Allergy, Asthma, and Immunology|American Academy of Allergy, Asthma and Immunology]].<ref name=":1" /><ref>{{cite journal | vauthors = Witt CM, Brinkhaus B | title = Efficacy, effectiveness and cost-effectiveness of acupuncture for allergic rhinitis – An overview about previous and ongoing studies | journal = Autonomic Neuroscience | volume = 157 | issue = 1–2 | pages = 42–5 | date = October 2010 | pmid = 20609633 | doi = 10.1016/j.autneu.2010.06.006 | s2cid = 31349218 }}</ref>

==Epidemiology==
Allergic rhinitis is the type of [[allergy]] that affects the greatest number of people.<ref name=Fire2002/> In Western countries, between 10 and 30 percent of people are affected in a given year.<ref name=NEJM2015/> It is most common between the ages of twenty and forty.<ref name=NEJM2015/>

==History==
The first accurate description is from the 10th century physician [[Rhazes]].<ref name="Ric2009"/> Pollen was identified as the cause in 1859 by [[Charles Blackley]].<ref name="BBC2014"/> In 1906 the mechanism was determined by [[Clemens von Pirquet]].<ref name=Fire2002/> The link with [[hay]] came about due to an early (and incorrect) theory that the symptoms were brought about by the smell of new hay.<ref name="Lancet1838"/><ref name="Kar2014"/> Although the scent per se is irrelevant, the [[correlation]] with hay checks out, as peak hay-harvesting season overlaps with peak pollen season, and hay-harvesting work puts people in close contact with seasonal allergens.

==See also==
*[[Hemp fever]]

== References ==
{{Reflist}}

== Further reading ==
{{Refbegin}}
* {{cite web | title=Sublingual Immunotherapy (SLIT) Allergy Tablets - American Academy of Allergy, Asthma & Immunology | url=https://www.aaaai.org/Tools-for-the-Public/Drug-Guide/Sublingual-Immunotherapy-(SLIT)-Allergy-Tablets | access-date=April 28, 2022 | archive-date=March 3, 2022 | archive-url=https://web.archive.org/web/20220303203330/https://www.aaaai.org/Tools-for-the-Public/Drug-Guide/Sublingual-Immunotherapy-(SLIT)-Allergy-Tablets | url-status=live }}
{{Refend}}

== External links ==

{{Allergic conditions}}
{{Hypersensitivity and autoimmune diseases}}
{{Respiratory pathology}}
{{Nasal preparations}}

{{Medical resources
| DiseasesDB = 31140
| ICD10      = {{ICD10|J|30||j|30}}
| ICD9       = {{ICD9|477}}
| ICDO       =
| OMIM       = 607154
| MedlinePlus = 000813
| eMedicineSubj = ent
| eMedicineTopic = 194
| eMedicine_mult = {{eMedicine2|med|104}}, {{eMedicine2|ped|2560}}
| MeshID = D012221
}}

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{{DEFAULTSORT:Allergic Rhinitis}}
[[Category:Allergology]]
[[Category:Steroid-responsive inflammatory conditions]]
[[Category:Type I hypersensitivity]]
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[[Category:Wikipedia emergency medicine articles ready to translate]]