View source for Anosmia

{{Short description|Inability to smell}}
{{Infobox medical condition (new)
 |name          = Anosmia
 |synonym       = Loss of smell, smell blindness,<ref name=Coon2014/> odor blindness
 |image         = Anosmia.jpg
 |image_size    =
 |alt           = A side view anatomical drawing of the nasal sinuses depicting inflamed mucosa
 |caption       = Inflamed nasal mucosa causing anosmia
 |pronounce     = {{IPAc-en|æ|n|ˈ|ɒ|z|m|i|ə|}}
 |specialty     = [[Otorhinolaryngology]]
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 |types         = Partial, total<ref name=Jon2010/>
 |causes        =
 |risks         =
 |diagnosis     =
 |differential  =
 |prevention    =
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'''Anosmia''', also known as '''smell blindness''', is the lack of ability to detect one or more [[Odor|smells]].<ref name="Coon2014">{{cite book| vauthors = Coon D, Mitterer J |chapter-url=https://books.google.com/books?id=-4jCBAAAQBAJ&pg=PA136|title=Introduction to Psychology: Gateways to Mind and Behavior|date=2014|publisher=Cengage Learning|isbn=978-1-305-09187-0|location=Boston|page=136|language=en|chapter=4. Sensation and perception|lccn=2014942026 }}</ref><ref name="Jon2010">{{cite book| vauthors = Jones N |chapter-url=https://books.google.com/books?id=arSSpm-OgjYC&pg=PA25|title=Practical Rhinology|date=2010|publisher=CRC Press|isbn=978-1-4441-0861-3| veditors = Jones N  |pages=24–25|language=en|chapter=2. Making sense of symptoms}}</ref> Anosmia may be temporary or permanent.<ref name=Li2020>{{cite book | vauthors = Li X, Lui F | chapter = Anosmia |date=6 July 2020 | chapter-url= https://www.ncbi.nlm.nih.gov/books/NBK482152/ | title = StatPearls |publisher=StatPearls Publishing |pmid=29489163 |access-date=1 December 2020 }}</ref> It differs from [[hyposmia]], which is a decreased sensitivity to some or all smells.<ref name=Jon2010/>

Anosmia can be categorized into acquired anosmia and [[congenital anosmia]]. Acquired anosmia develops later in life due to various causes, such as upper respiratory infections, [[Head injury|head trauma]], or [[Neurodegenerative disease|neurodegenerative diseases]].<ref name="NCBI2021">{{cite journal |title=Anosmia - StatPearls - NCBI Bookshelf |url=https://www.ncbi.nlm.nih.gov/books/NBK482152/ |website=NCBI |date=2021 |pmid=29489163 |access-date=2024-07-06 |last1=Li |first1=X. |last2=Lui |first2=F. }}</ref> In contrast, congenital anosmia is present from birth and is typically caused by genetic factors or developmental abnormalities of the olfactory system.<ref name="FifthSense">{{cite web |title=Congenital Anosmia |url=https://www.fifthsense.org.uk/congenital-anosmia/ |website=Fifth Sense |access-date=2024-07-06}}</ref> While acquired anosmia may have potential treatments depending on the underlying cause, such as medications or surgery, congenital anosmia currently has no known cure, and management focuses on safety precautions and coping strategies.<ref name="MayoClinic">{{cite web |title=Loss of smell (anosmia) Causes |url=https://www.mayoclinic.org/symptoms/loss-of-smell/basics/causes/sym-20050804 |website=Mayo Clinic |access-date=2024-07-06}}</ref>

Anosmia can be due to a number of factors, including [[inflammation]] of the [[nasal mucosa]], blockage of [[nasal passage]]s, or destruction of [[temporal lobe|temporal lobular]] tissue.<ref name="huynh">{{cite journal | vauthors = Huynh PP, Ishii LE, Ishii M | title = What Is Anosmia? | journal = JAMA | volume = 324 | issue = 2 | page = 206 | date = July 2020 | pmid = 32556300 | doi = 10.1001/jama.2020.10966 | s2cid = 219916772 | doi-access = free }}</ref> Anosmia stemming from sinus inflammation is due to chronic mucosal changes in the lining of the [[paranasal sinus]] and in the middle and superior [[turbinate]]s.<ref>{{cite journal | vauthors = Helliwell T | title = Inflammatory diseases of the nasal cavities and paranasal sinuses | journal = Diagnostic Histopathology | volume = 16 | issue = 6 | pages = 255–264 | date = June 2010 | pmid = 32336992 | pmc = 7172334 | doi = 10.1016/j.mpdhp.2010.03.008 }}</ref><ref name="pmid35386650">{{cite journal | vauthors = Lin YT, Yeh TH | title = Studies on Clinical Features, Mechanisms, and Management of Olfactory Dysfunction Secondary to Chronic Rhinosinusitis | journal = Frontiers in Allergy | volume = 3 | issue = | article-number = 835151 | date = 2022 | pmid = 35386650 | pmc = 8974686 | doi = 10.3389/falgy.2022.835151 | doi-access = free }}</ref>

When anosmia is caused by inflammatory changes in the nasal passageways, it is treated simply by reducing inflammation.<ref name=Knight1998>{{cite journal | vauthors = Knight A | title = Anosmia | journal = Lancet | volume = 2 | issue = 8609 | page = 512 | date = August 1988 | pmid = 2900434 | doi = 10.1016/s0140-6736(88)90160-2 | s2cid = 208793859 }}{{subscription required}}</ref><ref>{{Citation |title=Sinusitis Clinical Practice Guideline Quick Reference Tools |date=2022-04-11 |work=Pediatric Clinical Practice Guidelines & Policies |pages=481–484 |publisher=American Academy of Pediatrics |doi=10.1542/9781610026086-part01-27 |isbn=978-1-61002-608-6}}</ref> It can be caused by chronic [[meningitis]] and [[neurosyphilis]] that would increase intracranial pressure over a long period of time,<ref>{{cite journal |year=1943 |title=Anosmia |journal=The Lancet |volume=241 |issue=6228 |page=55 |doi=10.1016/S0140-6736(00)89085-6|s2cid=241387103 }}</ref> and, in some cases, by [[ciliopathy]],<ref name="Uytingco2019">{{cite journal | vauthors = Uytingco CR, Green WW, Martens JR | title = Olfactory Loss and Dysfunction in Ciliopathies: Molecular Mechanisms and Potential Therapies | journal = Current Medicinal Chemistry | volume = 26 | issue = 17 | pages = 3103–3119 | date = 2019 | pmid = 29303074 | pmc = 6034980 | doi = 10.2174/0929867325666180105102447 }}</ref> including ciliopathy due to [[primary ciliary dyskinesia]].<ref>{{cite journal | vauthors = Ul Hassan A, Hassan G, Khan SH, Rasool Z, Abida A | title = Ciliopathy with special emphasis on kartageners syndrome | journal = International Journal of Health Sciences | volume = 3 | issue = 1 | pages = 65–69 | date = January 2009 | pmid = 21475513 | pmc = 3068795 }}</ref>

The term derives from the [[Neo-Latin]] ''anosmia'', based on [[Ancient Greek]] ἀν- (''an''-) + ὀσμή (''osmḗ'' 'smell'; another related term, [[hyperosmia]], refers to an increased ability to smell). Some people may be anosmic for one particular odor, a condition known as "specific anosmia". The absence of the sense of smell from birth is known as [[congenital anosmia]].<ref>{{cite journal | vauthors = Boesveldt S, Postma EM, Boak D, Welge-Luessen A, Schöpf V, Mainland JD, Martens J, Ngai J, Duffy VB | display-authors = 6 | title = Anosmia-A Clinical Review | journal = Chemical Senses | volume = 42 | issue = 7 | pages = 513–523 | date = September 2017 | pmid = 28531300 | pmc = 5863566 | doi = 10.1093/chemse/bjx025 }}</ref>

In the United States, 3% of people aged over 40 are affected by anosmia.<ref name=Li2020/>

Anosmia is a common symptom of [[COVID-19]] and can persist as [[long COVID]].<ref>{{Cite web|title=Q&A: COVID-19 and loss of smell, taste|url=https://www.mayoclinichealthsystem.org/hometown-health/featured-topic/q-and-a-covid-19-and-loss-of-smell-taste|access-date=2022-02-23|website=Mayo Clinic Health System|language=en}}</ref>

==Definition==
Anosmia is the inability to [[Odor|smell]].<ref name="Coon2014"/> It may be partial or total, and can be specific to certain smells.<ref name=Jon2010/> Reduced sensitivity to some or all smells is [[hyposmia]].<ref name=Jon2010/>

==Signs and symptoms==
Anosmia can have a number of harmful effects.<ref name=Toller>{{cite journal | vauthors = Toller SV | title = Assessing the impact of anosmia: review of a questionnaire's findings | journal = Chemical Senses | volume = 24 | issue = 6 | pages = 705–712 | date = December 1999 | pmid = 10587505 | doi = 10.1093/chemse/24.6.705 | doi-access = free }}</ref> People with sudden onset anosmia may find food less appetizing, though [[congenital]] anosmics rarely complain about this, and none report a loss in weight. Loss of smell can also be dangerous because it hinders the detection of [[gas leak]]s, fire, and spoiled food. Misconceptions of anosmia as trivial can make it more difficult for a patient to receive the same types of medical aid as someone who has lost other senses, such as hearing or sight.{{citation needed|date=December 2020}}

Many experience one sided loss of smell, often as a result of minor head trauma. This type of anosmia is normally only detected if both of the nostrils are tested separately. Using this method of testing each nostril separately will often show a reduced or even completely absent sense of smell in either one nostril or both, something which is often not revealed if both nostrils are simultaneously tested.<ref name="Harvey2006">{{cite journal| vauthors = Harvey P |date=February 2006|title=Anosmia|url=http://pn.bmj.com/content/6/1/65.extract|journal=[[Practical Neurology]]|volume=6|issue=1|page=65 }}</ref>

Losing an established and sentimental [[olfactory memory|smell memory]] (e.g. the [[Smell of freshly cut grass|smell of grass]], of the grandparents' attic, of a particular book, of loved ones, or of oneself) has been known to cause feelings of [[clinical depression|depression]].<ref name="bbc1">{{cite news| url=https://news.bbc.co.uk/2/hi/uk_news/magazine/6199605.stm |work=BBC News |title=Sense and scent ability | vauthors = Heald C |date=December 27, 2006 |access-date=April 25, 2010}}</ref>{{Better source needed|date=November 2020}}

Loss of the ability to smell may lead to the loss of [[libido]], but this usually does not apply to those with olfactory dysfunction at birth.<ref name="bbc1"/><ref>{{cite journal | vauthors = Gudziol V, Wolff-Stephan S, Aschenbrenner K, Joraschky P, Hummel T | title = Depression resulting from olfactory dysfunction is associated with reduced sexual appetite--a cross-sectional cohort study | journal = The Journal of Sexual Medicine | volume = 6 | issue = 7 | pages = 1924–1929 | date = July 2009 | pmid = 19453919 | doi = 10.1111/j.1743-6109.2009.01266.x }}</ref>

Often people who have loss of smell at birth report that they pretended to be able to smell as children because they thought that smelling was something that older/mature people could do, or did not understand the concept of smelling but did not want to appear different from others. When children get older, they often realize and report to their parents that they do not actually possess a sense of smell, often to the surprise of their parents.{{citation needed|date=November 2017}}

==Causes==
A temporary loss of smell can be caused by a blocked [[human nose|nose]] or infection. In contrast, a permanent loss of smell may be caused by death of [[olfactory receptor neuron]]s in the nose or by [[Acquired brain injury|brain injury]] in which there is damage to the [[olfactory nerve]] or damage to brain areas that process smell (see [[olfactory system]]). The lack of the sense of smell at birth, usually due to genetic factors, is referred to as ''[[congenital anosmia]].'' Family members of the patient with congenital anosmia are often found with similar histories; this suggests that the anosmia may follow an autosomal dominant pattern.<ref>{{cite journal| vauthors = Waguespack RW |year=1992|title=Congenital Anosmia|url=https://jamanetwork.com/journals/jamaotolaryngology/article-abstract/620279|journal=Archives of Otolaryngology–Head & Neck Surgery|volume=118|issue=1|page=10|doi=10.1001/archotol.1992.01880010012002|url-access=subscription}}</ref> Anosmia may very occasionally be an early sign of a degenerative brain disease such as [[Parkinson's disease]] and [[Alzheimer's disease]].<ref>{{Citation |last1=Walker |first1=Ian M. |title=Olfaction as an early marker of Parkinson's disease and Alzheimer's disease |date=2021 |work=Handbook of Clinical Neurology |volume=182 |pages=317–329 |url=https://linkinghub.elsevier.com/retrieve/pii/B9780128199732000307 |access-date=2024-12-26 |publisher=Elsevier |language=en |doi=10.1016/b978-0-12-819973-2.00030-7 |isbn=978-0-12-819973-2 |last2=Fullard |first2=Michelle E. |last3=Morley |first3=James F. |last4=Duda |first4=John E.|pmid=34266602 |url-access=subscription }}</ref>

Another specific cause of permanent loss could be from damage to olfactory receptor neurons because of use of certain types of [[nasal spray]]; i.e., those that cause vasoconstriction of the nasal microcirculation. To avoid such damage and the subsequent risk of loss of smell, vasoconstricting nasal sprays should be used only when absolutely necessary and then for only a short amount of time. Non-vasoconstricting sprays, such as those used to treat allergy-related congestion, are safe to use for prescribed periods of time.<ref>[https://web.archive.org/web/20060101000005/http://www.coldcure.com/anosmia/anosmia.html Preventing Anosmia from Intranasal Zinc Administration<!-- Bot generated title -->]{{MEDRS|date=June 2014}}</ref> Anosmia can also be caused by nasal polyps. These polyps are found in people with allergies, histories of sinusitis, and family history. Individuals with [[cystic fibrosis]] often develop nasal polyps.{{citation needed|date=December 2020}}

[[Amiodarone]] is a drug used in the treatment of arrhythmias of the heart. A clinical study demonstrated that the use of this drug induced anosmia in some patients. Although rare, there was a case in which a 66-year-old male was treated with amiodarone for [[ventricular tachycardia]]. After the use of the drug he began experiencing olfactory disturbance, however after decreasing the dosage of amiodarone, the severity of the anosmia decreased accordingly, suggesting a relationship between use of amiodarone to the development of anosmia.<ref>{{cite journal | vauthors = Maruyama T, Yasuda S, Odashiro K, Kaji Y, Harada M | title = Anosmia induced by amiodarone | journal = The American Journal of Medicine | volume = 120 | issue = 11 | article-number = e9 | date = November 2007 | pmid = 17976411 | doi = 10.1016/j.amjmed.2006.08.029 | doi-access = free }}</ref>

=== COVID-19-related anosmia ===
Chemosensory disturbances, including loss of smell or taste, are the predominant neurological symptom of [[COVID-19]].<ref>{{cite journal | vauthors = Lechien JR, Chiesa-Estomba CM, De Siati DR, Horoi M, Le Bon SD, Rodriguez A, Dequanter D, Blecic S, El Afia F, Distinguin L, Chekkoury-Idrissi Y, Hans S, Delgado IL, Calvo-Henriquez C, Lavigne P, Falanga C, Barillari MR, Cammaroto G, Khalife M, Leich P, Souchay C, Rossi C, Journe F, Hsieh J, Edjlali M, Carlier R, Ris L, Lovato A, De Filippis C, Coppee F, Fakhry N, Ayad T, Saussez S | display-authors = 3 | title = Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study | journal = European Archives of Oto-Rhino-Laryngology | volume = 277 | issue = 8 | pages = 2251–2261 | date = August 2020 | pmid = 32253535 | pmc = 7134551 | doi = 10.1007/s00405-020-05965-1 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Xydakis MS, Dehgani-Mobaraki P, Holbrook EH, Geisthoff UW, Bauer C, Hautefort C, Herman P, Manley GT, Lyon DM, Hopkins C | display-authors = 3 | title = Smell and taste dysfunction in patients with COVID-19 | journal = The Lancet. Infectious Diseases | volume = 20 | issue = 9 | pages = 1015–1016 | date = September 2020 | pmid = 32304629 | pmc = 7159875 | doi = 10.1016/S1473-3099(20)30293-0 | doi-access = free }}</ref> As many as 80% of COVID-19 patients exhibit some change in [[chemesthesis]], including smell. Loss of smell has also been found to be more predictive of COVID-19 than all other symptoms, including fever, cough, or fatigue, based on a survey of 2 million participants in the UK and US.<ref>{{cite journal | vauthors = Menni C, Valdes AM, Freidin MB, Sudre CH, Nguyen LH, Drew DA, Ganesh S, Varsavsky T, Cardoso MJ, El-Sayed Moustafa JS, Visconti A, Hysi P, Bowyer RC, Mangino M, Falchi M, Wolf J, Ourselin S, Chan AT, Steves CJ, Spector TD | display-authors = 3 | title = Real-time tracking of self-reported symptoms to predict potential COVID-19 | journal = Nature Medicine | volume = 26 | issue = 7 | pages = 1037–1040 | date = July 2020 | pmid = 32393804 | pmc = 7751267 | doi = 10.1038/s41591-020-0916-2 | doi-access = free }}</ref> Google searches for "smell", "loss of smell", "anosmia", and other similar terms increased since the early months of the pandemic, and strongly correlated with increases in daily cases and deaths.<ref>{{cite journal | vauthors = Walker A, Hopkins C, Surda P | title = Use of Google Trends to investigate loss-of-smell-related searches during the COVID-19 outbreak | journal = International Forum of Allergy & Rhinology | volume = 10 | issue = 7 | pages = 839–847 | date = July 2020 | pmid = 32279437 | pmc = 7262261 | doi = 10.1002/alr.22580 | doi-access = free }}</ref> Research into the mechanisms underlying these symptoms is currently ongoing.<ref>Shelton, J. F., Shastri, A. J., Fletez-Brant, K., Aslibekyan, S., & Auton, A. (2022). The UGT2A1/UGT2A2 locus is associated with COVID-19-related loss of smell or taste. Nature Genetics, 54(2), 121-124.</ref><ref>{{cite journal | vauthors = Cooper KW, Brann DH, Farruggia MC, Bhutani S, Pellegrino R, Tsukahara T, Weinreb C, Joseph PV, Larson ED, Parma V, Albers MW, Barlow LA, Datta SR, Di Pizio A | display-authors = 6 | title = COVID-19 and the Chemical Senses: Supporting Players Take Center Stage | journal = Neuron | volume = 107 | issue = 2 | pages = 219–233 | date = July 2020 | pmid = 32640192 | pmc = 7328585 | doi = 10.1016/j.neuron.2020.06.032 | doi-access = free }}</ref>

Many countries list anosmia as an official COVID-19 symptom, and some have developed "smell tests" as potential screening tools.<ref>{{Cite medRxiv |vauthors=Iravani B, Arshamian A, Ravia A, Mishor E, Snitz K, Shushan S, Roth Y, Perl O, Honigstein D, Weissgross R, Karagach S |display-authors=6 |date=11 May 2020 |title=Relationship between odor intensity estimates and COVID-19 population prediction in a Swedish sample |medrxiv=10.1101/2020.05.07.20094516}}</ref><ref>{{Cite medRxiv |vauthors=Rodriguez S, Cao L, Rickenbacher GT, Benz EG, Magdamo C, Ramirez Gomez LA, Holbrook E, Dhilla Albers A, Gallagher R, Westover MB, Evans KE, Tatar D, Mukerji S, Zafonte R, Boyer EW, Yu CR, Albers MW |display-authors=6 |title=Innate immune signaling in the olfactory epithelium reduces odorant receptor levels: modeling transient smell loss in COVID-19 patients |date=June 2020 |medrxiv=10.1101/2020.06.14.20131128}}</ref>

In 2020, the Global Consortium for Chemosensory Research, a collaborative research organization of international smell and taste researchers, formed to investigate loss of smell and related chemosensory symptoms.<ref>{{cite web|title=Global Consortium for Chemosensory Research|url=https://gcchemosensr.org/|access-date=10 July 2020|website=Global Consortium for Chemosensory Research (GCCR)|language=en}}</ref>

==== Decision-making in COVID-19 patients ====
Studies have indicated that patients who presented with anosmia during the acute phase of COVID-19 are more likely to develop changes in decision-making, exhibiting more impulsive responses, which are associated with functional and structural brain changes.<ref>{{cite journal |last1=Kausel |first1=L. |title=Patients recovering from COVID-19 who presented with anosmia during their acute episode have behavioral, functional, and structural brain alterations |journal=Scientific Reports |volume=14 |article-number=19049 |year=2024 |issue=1 |doi=10.1038/s41598-024-69772-y |pmid=39152190 |pmc=11329703 |bibcode=2024NatSR..1419049K }}</ref>

=== Possible causes ===
{{more medical citations|section|date=October 2025}}
{{columns-list|colwidth=30em|
* Upper respiratory tract infection (such as [[sinusitis]], the [[common cold]])<ref name="Doty2001">{{cite journal | vauthors = Doty RL, Mishra A | title = Olfaction and its alteration by nasal obstruction, rhinitis, and rhinosinusitis | journal = The Laryngoscope | volume = 111 | issue = 3 | pages = 409–423 | date = March 2001 | pmid = 11224769 | pmc = 7165948 | doi = 10.1097/00005537-200103000-00008 }}</ref>
* [[COVID-19]]<ref>{{cite journal | vauthors = Grant MC, Geoghegan L, Arbyn M, Mohammed Z, McGuinness L, Clarke EL, Wade RG | title = The prevalence of symptoms in 24,410 adults infected by the novel coronavirus (SARS-CoV-2; COVID-19): A systematic review and meta-analysis of 148 studies from 9 countries | journal = PLOS ONE | volume = 15 | issue = 6 | article-number = e0234765 | date = 23 June 2020 | pmid = 32574165 | pmc = 7310678 | doi = 10.1371/journal.pone.0234765 | doi-access = free | bibcode = 2020PLoSO..1534765G }}</ref><ref>{{cite web |title=Coronavirus Disease 2019 (COVID-19) – Symptoms |url=https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html |website=Centers for Disease Control and Prevention |access-date=14 May 2020 |language=en-us |date=13 May 2020}}</ref>
* [[Nasal polyps]]<ref name="Ta2010">{{cite journal | vauthors = Ta NH | title = Will we ever cure nasal polyps? | journal = Annals of the Royal College of Surgeons of England | volume = 101 | issue = 1 | pages = 35–39 | date = January 2019 | pmid = 30286644 | pmc = 6303820 | doi = 10.1308/rcsann.2018.0149 }}</ref>
* Idiopathic [[hypogonadotropic hypogonadism]]
* [[Hypothyroidism]]
* Head trauma, damage to the [[ethmoid bone]]<ref name="Doty1997">{{cite journal | vauthors = Doty RL, Yousem DM, Pham LT, Kreshak AA, Geckle R, Lee WW | title = Olfactory dysfunction in patients with head trauma | journal = Archives of Neurology | volume = 54 | issue = 9 | pages = 1131–1140 | date = September 1997 | pmid = 9311357 | doi = 10.1001/archneur.1997.00550210061014 }}</ref>
* [[Dementia with Lewy bodies]]
* [[Tumors]] of the [[frontal lobe]]
* [[Antibiotics]]
* [[Fibromyalgia]]
* [[Multiple sclerosis]]
* Exposure to [[hydrogen sulfide]] ({{chem|H|2|S}}) by paralysis of the olfactory nerve.<ref>{{Cite book | author = National Research Council (US) Committee on Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants|url=https://www.ncbi.nlm.nih.gov/books/NBK219913/|title=Hydrogen Sulfide|date=2009|publisher=National Academies Press (US)|language=en}}</ref>
* [[Hypoglycaemia]]
* [[Diabetes]]
* [[Asthma]] or [[allergy]]
* [[Hayfever]]
* [[Chronic obstructive pulmonary disease]] (COPD)
* Long term [[alcoholism]]
* [[Cushing's syndrome]]
* Exposure to a chemical that burns the inside of the nose
* [[Stroke]]
* [[Epilepsy]]
* Radiation therapy to the head and neck
* [[Liver disease|Liver]] or [[kidney disease]]
* [[Parkinson's disease]]<ref name="Doty1988">{{cite journal | vauthors = Doty RL, Deems DA, Stellar S | title = Olfactory dysfunction in parkinsonism: a general deficit unrelated to neurologic signs, disease stage, or disease duration | journal = Neurology | volume = 38 | issue = 8 | pages = 1237–1244 | date = August 1988 | pmid = 3399075 | doi = 10.1212/WNL.38.8.1237 | s2cid = 3009692 }}</ref>
* [[Alzheimer's disease]]<ref name="Murphy1988">{{cite journal | vauthors = Murphy C | title = Loss of olfactory function in dementing disease | journal = Physiology & Behavior | volume = 66 | issue = 2 | pages = 177–182 | date = April 1999 | pmid = 10336141 | doi = 10.1016/S0031-9384(98)00262-5 | s2cid = 26110446 }}</ref>
* Toxins (especially [[acrylate]]s, [[methacrylate]]s<ref name="Schwartz">{{cite journal | vauthors = Schwartz BS, Doty RL, Monroe C, Frye R, Barker S | title = Olfactory function in chemical workers exposed to acrylate and methacrylate vapors | journal = American Journal of Public Health | volume = 79 | issue = 5 | pages = 613–618 | date = May 1989 | pmid = 2784947 | pmc = 1349504 | doi = 10.2105/AJPH.79.5.613 }}</ref> and [[cadmium]]<ref name="Rose1992">{{cite journal | vauthors = Rose CS, Heywood PG, Costanzo RM | title = Olfactory impairment after chronic occupational cadmium exposure | journal = Journal of Occupational Medicine | volume = 34 | issue = 6 | pages = 600–605 | date = June 1992 | pmid = 1619490 }}</ref><ref name="Rydzewski1998">{{cite journal | vauthors = Rydzewski B, Sułkowski W, Miarzyńska M | title = Olfactory disorders induced by cadmium exposure: a clinical study | journal = International Journal of Occupational Medicine and Environmental Health | volume = 11 | issue = 3 | pages = 235–245 | year = 1998 | pmid = 9844306 }}</ref>)
* Old age<ref>{{cite journal | vauthors = Doty RL, Shaman P, Applebaum SL, Giberson R, Siksorski L, Rosenberg L | title = Smell identification ability: changes with age | journal = Science | volume = 226 | issue = 4681 | pages = 1441–1443 | date = December 1984 | pmid = 6505700 | doi = 10.1126/science.6505700 | bibcode = 1984Sci...226.1441D }}</ref>
* [[Kallmann syndrome]]
* [[Primary ciliary dyskinesia]]
* [[Post-perfusion syndrome]]
* [[Laryngectomy]] with permanent [[tracheostomy]]
* [[Esthesioneuroblastoma]] is an exceedingly rare cancerous tumor that originates in or near the [[olfactory nerve]]. Symptoms are anosmia (loss of sense of smell) often accompanied by chronic [[sinusitis]].<ref>{{cite journal | vauthors = Somenek M | veditors = Harris JE |title=Esthesioneuroblastoma |url=http://emedicine.medscape.com/article/278047-overview |date=October 30, 2009 |journal=[[eMedicine]]}}</ref>
* [[Insufflation (medicine)|Intranasal]] [[Recreational drug use|drug use]]
* [[Aspirin-exacerbated respiratory disease]], also known as Samter's triad
* [[Foster Kennedy syndrome]]
* [[Cadmium poisoning]]
* [[Tobacco smoking|Smoking]]
* [[Neurotropic virus]]<ref>{{cite journal | vauthors = Seo BS, Lee HJ, Mo JH, Lee CH, Rhee CS, Kim JW | title = Treatment of postviral olfactory loss with glucocorticoids, Ginkgo biloba, and mometasone nasal spray | journal = Archives of Otolaryngology–Head & Neck Surgery | volume = 135 | issue = 10 | pages = 1000–1004 | date = October 2009 | pmid = 19841338 | doi = 10.1001/archoto.2009.141 | doi-access = free }}
*{{lay source |template = cite press release|url = https://www.sciencedaily.com/releases/2009/10/091019172331.htm|title = Study Examines Treatment For Olfactory Loss After Viral Infection|date = October 21, 2009 |website = ScienceDaily }}</ref>
* [[Schizophrenia]]<ref>{{cite journal | vauthors = Rupp CI, Fleischhacker WW, Kemmler G, Kremser C, Bilder RM, Mechtcheriakov S, Szeszko PR, Walch T, Scholtz AW, Klimbacher M, Maier C, Albrecht G, Lechner-Schoner T, Felber S, Hinterhuber H | display-authors = 6 | title = Olfactory functions and volumetric measures of orbitofrontal and limbic regions in schizophrenia | journal = Schizophrenia Research | volume = 74 | issue = 2–3 | pages = 149–161 | date = May 2005 | pmid = 15721995 | doi = 10.1016/j.schres.2004.07.010 | s2cid = 11026266 }}</ref>
* [[Pernicious anemia]]
* [[Zinc deficiency]]
* [[Bell's Palsy]] or nerve paralysis and damage
* [[Idiopathic intracranial hypertension]]
* [[Sella turcica|Suprasellar]] [[meningioma]]
* [[Refsum's disease]]
* [[Adrenergic agonist]]s or withdrawal from [[alpha blocker]]s (vasoconstriction)
* [[Sarcoidosis]]<ref>{{cite journal | vauthors = Kieff DA, Boey H, Schaefer PW, Goodman M, Joseph MP | title = Isolated neurosarcoidosis presenting as anosmia and visual changes | journal = Otolaryngology–Head and Neck Surgery | volume = 117 | issue = 6 | pages = S183–S186 | date = December 1997 | pmid = 9419143 | doi = 10.1016/S0194-5998(97)70097-4 }}</ref>
* [[Zinc#Precautions|Zinc-based intranasal cold products, including remedies labelled as "homeopathic"]]<ref name=NYT1>{{cite news |url= https://www.nytimes.com/2009/06/17/health/policy/17nasal.html | vauthors = Harris G |date=June 16, 2009 |title=F.D.A. Warns Against Use of Popular Cold Remedy |work=New York Times}}</ref>
* [[Chronic atrophic rhinitis]]
* [[Paget's disease of bone]]<ref>{{cite journal | vauthors = Wheeler TT, Alberts MA, Dolan TA, McGorray SP | title = Dental, visual, auditory and olfactory complications in Paget's disease of bone | journal = Journal of the American Geriatrics Society | volume = 43 | issue = 12 | pages = 1384–1391 | date = December 1995 | pmid = 7490390 | doi = 10.1111/j.1532-5415.1995.tb06618.x | s2cid = 26893932 }}</ref>
* [[Cerebral aneurysm]]<ref>{{cite journal | vauthors = Eriksen KD, Bøge-Rasmussen T, Kruse-Larsen C | title = Anosmia following operation for cerebral aneurysms in the anterior circulation | journal = Journal of Neurosurgery | volume = 72 | issue = 6 | pages = 864–865 | date = June 1990 | pmid = 2338570 | doi = 10.3171/jns.1990.72.6.0864 }}</ref>
* [[Granulomatosis with polyangiitis]]
* [[Primary amoebic meningoencephalitis]]
* [[Myasthenia gravis]]<ref>{{cite journal | vauthors = Leon-Sarmiento FE, Bayona EA, Bayona-Prieto J, Osman A, Doty RL | title = Profound olfactory dysfunction in myasthenia gravis | journal = PLOS ONE | volume = 7 | issue = 10 | article-number = e45544 | year = 2012 | pmid = 23082113 | pmc = 3474814 | doi = 10.1371/journal.pone.0045544 | doi-access = free | bibcode = 2012PLoSO...745544L }}</ref>
* [[Snakebite]]<ref>{{cite journal | vauthors = Churchman A, O'Leary MA, Buckley NA, Page CB, Tankel A, Gavaghan C, Holdgate A, Brown SG, Isbister GK | display-authors = 6 | title = Clinical effects of red-bellied black snake (Pseudechis porphyriacus) envenoming and correlation with venom concentrations: Australian Snakebite Project (ASP-11) | journal = The Medical Journal of Australia | volume = 193 | issue = 11–12 | pages = 696–700 | date = December 2010 | pmid = 21143062 | doi = 10.5694/j.1326-5377.2010.tb04108.x | s2cid = 15915175 }}</ref>
* Idiopathic anosmia (cause cannot be determined)<ref name=Li2020/>
}}

==Diagnosis==
Diagnosis begins with a detailed history, including possible related injuries, such as upper respiratory infections or head injury. The examination may involve nasal [[endoscopy]] for obstructive factors such as polyps or swelling.<ref name=huynh/> A nervous system examination is performed to see if the [[cranial nerves]] are affected.<ref name=huynh/> On occasion, after head traumas, there are people who have unilateral anosmia. The sense of smell should be tested individually in each nostril.<ref name=Harvey2006/>

Many cases of congenital anosmia remain unreported and undiagnosed. Since the disorder is present from birth the individual may have little or no understanding of the sense of smell, hence is unaware of the deficit.<ref>{{cite journal | vauthors = Vowles RH, Bleach NR, Rowe-Jones JM | title = Congenital anosmia | journal = International Journal of Pediatric Otorhinolaryngology | volume = 41 | issue = 2 | pages = 207–214 | date = August 1997 | pmid = 9306177 | doi = 10.1016/S0165-5876(97)00075-X }}</ref> It may also lead to reduction of appetite.<ref>{{cite journal | vauthors = Sumner D |year=1971 |title=Appetite and Anosmia |journal=The Lancet |volume=297 |issue=7706 |page=970 |doi=10.1016/S0140-6736(71)91470-X}}</ref>

==Treatment==
Though anosmia caused by brain damage cannot be treated, anosmia caused by inflammatory changes in the mucosa may be treated with [[glucocorticoids]]. Reduction of inflammation through the use of oral glucocorticoids such as prednisone, followed by long term topical glucocorticoid nasal spray, would easily and safely treat the anosmia. A prednisone regimen is adjusted based on the degree of the thickness of mucosa, the discharge of oedema and the presence or absence of nasal polyps.<ref name=Knight1998/> However, the treatment is not permanent and may have to be repeated after a short while.<ref name=Knight1998 /> Together with medication, pressure of the upper area of the nose must be mitigated through aeration and drainage.<ref>{{cite journal | vauthors = Turnley WH | title = Anosmia | journal = The Laryngoscope | volume = 73 | issue = 4 | pages = 468–473 | date = April 1963 | pmid = 13994924 | doi = 10.1288/00005537-196304000-00012 | s2cid = 221921289 }}</ref>

Anosmia caused by a [[nasal polyp]] may be treated by steroidal treatment or removal of the polyp.<ref>{{cite journal |title=Nasal Polyps Treatment & Management| vauthors = McClay JE |date=May 1, 2014 |url=http://emedicine.medscape.com/article/994274-treatment |journal=[[Medscape]]}}</ref>

Although very early in development, [[gene therapy]] has restored a sense of smell in mice with congenital anosmia when caused by [[ciliopathy]]. In this case, a genetic condition had affected cilia in their bodies which normally enabled them to detect air-borne chemicals, and an [[adenovirus]] was used to implant a working version of the [[IFT88]] gene into defective cells in the nose, which restored the cilia and allowed a sense of smell.<ref>{{cite journal | vauthors = McIntyre JC, Davis EE, Joiner A, Williams CL, Tsai IC, Jenkins PM, McEwen DP, Zhang L, Escobado J, Thomas S, Szymanska K, Johnson CA, Beales PL, Green ED, Mullikin JC, Sabo A, Muzny DM, Gibbs RA, Attié-Bitach T, Yoder BK, Reed RR, Katsanis N, Martens JR | display-authors = 6 | title = Gene therapy rescues cilia defects and restores olfactory function in a mammalian ciliopathy model | journal = Nature Medicine | volume = 18 | issue = 9 | pages = 1423–1428 | date = September 2012 | pmid = 22941275 | pmc = 3645984 | doi = 10.1038/nm.2860 }}</ref><ref>{{cite web |url=https://www.bbc.co.uk/news/health-19409154 |title=Gene therapy restores sense of smell in mice | vauthors = Gallagher J |date=September 3, 2012 |work=BBC News}}</ref>

==Epidemiology==
In the United States, 3% of people aged over 40 are affected by anosmia.<ref name=Li2020/>

In 2012, smell was assessed in persons aged 40 years and older with rates of anosmia/severe hyposmia of 0.3% at age 40–49 rising to 14.1% at age 80+. Rates of hyposmia were much higher: 3.7% at age 40–49 and 25.9% at 80+.<ref name="NHANES12">{{cite journal | vauthors = Hoffman HJ, Rawal S, Li CM, Duffy VB | title = New chemosensory component in the U.S. National Health and Nutrition Examination Survey (NHANES): first-year results for measured olfactory dysfunction | journal = Reviews in Endocrine & Metabolic Disorders | volume = 17 | issue = 2 | pages = 221–240 | date = June 2016 | pmid = 27287364 | pmc = 5033684 | doi = 10.1007/s11154-016-9364-1 }}</ref>

==Famous people with anosmia==
{{expand section|date=January 2024}} <!-- these people can be added back with appropriate sources: https://en.wikipedia.org/w/index.php?title=Anosmia&diff=prev&oldid=1191218965 -->
*[[Kathy Clugston]], British radio presenter<ref>{{cite news |first=Olivia |last=Parker |title='My partner does "armpit duty"': What it's like to live with no sense of smell |work=The Telegraph |date=11 April 2016 |url= https://www.telegraph.co.uk/health-fitness/body/my-partner-does-armpit-duty-what-its-like-to-live-with-no-sense/ |access-date=8 December 2018 }}</ref><ref>{{cite web |title=The Neglected Sense |publisher=BBC Radio 4 |url=https://www.bbc.co.uk/programmes/b076cg3n |access-date=8 December 2018 }}</ref>
*[[Ben Cohen (businessman)|Ben Cohen]] of Ben and Jerry's<ref>{{Cite web |last=DeGregory |first=Lane |date=30 November 2023 |title=For decades, a Florida woman had no sense of smell. Can she get it back? |url=https://www.tampabay.com/news/health/2023/11/30/regain-lost-sense-smell-florida-anosmia/ |access-date=2023-12-05 |website=Tampa Bay Times |language=en}}</ref><ref name="Sullivan 2021 o756">{{cite web | last=Sullivan | first=Justin | title=Ben & Jerry's' Ben Cohen Interview | website=Delish | date=8 Apr 2021 | url=https://www.delish.com/food-news/a36051690/ben-cohen-ben-jerrys-interview/ | access-date=6 Jan 2024}}</ref>
*[[Perrie Edwards]], singer of [[Little Mix]]<ref>{{cite news |last=Izundu |first=Chi Chi |date=7 October 2013 |title=Little Mix's Perrie Edwards: I have no sense of smell - BBC Newsbeat |work=BBC News |url=https://www.bbc.co.uk/news/newsbeat-23254182 |url-status=live |access-date=11 May 2020 |archive-url=https://web.archive.org/web/20201108003511/http://www.bbc.co.uk/newsbeat/article/23254182/little-mixs-perrie-edwards-i-have-no-sense-of-smell |archive-date=8 November 2020}}</ref>
*[[Lorenzo de' Medici]], 15th-century ruler of [[Florence]]<ref>{{Cite book |last=Ross |first=Janet |url=http://archive.org/details/livesofearlymedi00rossuoft |title=Lives of the early Medici as told in their correspondence |publisher=Chatto & Windus |year=1910 |page=144}}</ref>
*[[Bill Pullman]], American actor<ref>{{cite web |last1=Blair |first1=Iain |title=A Minute With: Bill Pullman about "Torchwood" |url=https://www.reuters.com/article/us-billpullman-idUSTRE7652KZ20110706/ |website=Reuters |access-date=30 July 2024 |language=English |date=6 July 2011}}</ref>
*[[Jason Sudeikis]], American actor<ref>{{cite news |url=http://www.people.com/article/olivia-wilde-answers-one-last-thing |title=Why Does Olivia Wilde's Fiancé Jason Sudeikis Think Her Cooking Always Tastes Good? |work=People |date=February 27, 2015 |access-date=April 25, 2016 |quote=My fiancé [Jason Sudeikis] has no sense of smell — he was born without it.... |archive-date=January 25, 2016 |archive-url=https://web.archive.org/web/20160125183619/http://www.people.com/article/olivia-wilde-answers-one-last-thing |url-status=live }}</ref>
* [[Simon Tatham]], British computer programmer<ref>{{Cite web |title=The 'Simon Tatham Has No Sense Of Smell' FAQ |url=https://www.chiark.greenend.org.uk/~sgtatham/smell.html |access-date=2025-08-02 |website=www.chiark.greenend.org.uk}}</ref>
* [[William Wordsworth]], poet<ref>{{cite journal |first=Rowan Rose |last=Boyson |title=Wordsworth's Anosmia |journal=La Questione Romantica |volume=3 |issue=2 |year=2011 |pages=63–80 }}</ref><ref>{{cite web |first=Nicola |last=Healey |title=Losing 'a sense sublime': anosmia and poetry |work=Wild Court |date=24 June 2025 |url=https://wildcourt.co.uk/losing-a-sense-sublime-anosmia-and-poetry/ |access-date=5 August 2025 }}</ref>

== See also ==
* [[Ageusia]], the loss of the sense of taste
* [[Anosmia Awareness Day]]
* [[Congenital anosmia]]
* [[Olfactory fatigue]], the habituation of the sense of smell to a particular odor or odors
* [[Parosmia]]
* [[Phantosmia]]
* [[Zicam]], a medicine that caused some users to permanently lose their sense of smell

== References ==
{{reflist}}

== Further reading ==
{{Scholia}}
{{refbegin|30em}}
* {{cite book |title=Remembering Smell: A Memoir of Losing—and Discovering—the Primal Sense | vauthors = Blodgett B |year=2010 |publisher=Houghton Mifflin Harcourt |isbn=978-0-618-86188-0 |url=https://archive.org/details/rememberingsmell00blod_0}}
* {{cite book | vauthors = Birnbaum M | date = 2011 | title = Season to Taste: How I Lost my Sense of Smell and Found my Way | publisher = Ecco | isbn = 978-0-06-191531-4 }}
* {{cite book | vauthors = DeVere R, Calvert M | date = 2010 | title = Navigating Smell and Taste Disorders | publisher = Demos Health | isbn = 978-1-932603-96-5 }}
* {{cite book | vauthors = Gilbert A | date = 2008 | title = What the Nose Knows.The Science of Scent in Everyday Life | publisher = Crown | isbn = 978-1-4000-8234-6}}
* {{cite book | vauthors = Herz R | date = 2007 | title = The Scent of Desire. Discovering Our Enigmatic Sense of Smell | publisher = HarperCollins | isbn = 978-0-06-082538-6}}
* {{cite book |title=Nunca sabrás a qué huele Bagdad (You will never know the smell of Bagdad)| vauthors = Tafalla M |year=2010 |publisher=Autonomous University of Barcelona |language=es |isbn=978-84-490-2611-9}} - Novel dealing with congenital anosmia.
* {{cite journal | vauthors = Keller A, Malaspina D | title = Hidden consequences of olfactory dysfunction: a patient report series | journal = BMC Ear, Nose and Throat Disorders | volume = 13 | issue = 1 | article-number = 8 | date = July 2013 | pmid = 23875929 | pmc = 3733708 | doi = 10.1186/1472-6815-13-8 | doi-access = free }}
* {{cite journal | vauthors = Tafalla M | title = A world without the olfactory dimension | journal = Anatomical Record | volume = 296 | issue = 9 | pages = 1287–1296 | date = September 2013 | pmid = 23907763 | doi = 10.1002/ar.22734 | doi-access = free }}
* {{cite journal | vauthors = Tafalla M | date = 2013 | url = http://aesthetics.ff.cuni.cz/archive/341/anosmic-aesthetics | title = Anosmic Aesthetics | journal = Estetika: The Central European Journal of Aesthetics | volume = 50 | location = Prag | issue = 1/2013 | pages = 53–80 | doi = 10.33134/eeja.103 | doi-access = free }}
* {{cite book | vauthors = Wilson DA, Stevenson RJ | date = 2006 | title = Learning to Smell. Olfactory Perception from Neurobiology to Behavior | publisher = The Johns Hopkins University Press | isbn = 978-0-8018-8368-2}}
{{refend}}

{{Medical resources
| Field = [[Neurology]]
| ICD10 = {{ICD10|R|43|0|r|40}}
| ICD9 = {{ICD9|781.1}}
| MeshID = D000857
}}

{{Cognition, perception, emotional state and behaviour symptoms and signs}}

[[Category:Neurological disorders]]
[[Category:Olfactory system]]
[[Category:COVID-19 symptoms]]
[[Category:Long COVID]]