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The term anosmia means lack of the sense of smell. It may also refer to a decreased sense of smell. Ageusia, a companion word, refers to a lack of taste sensation. Patients who actually have anosmia may complain wrongly of ageusia, although they retain the ability to distinguish salt, sweet, sour, and bitter—humans' only taste sensations.


Of the five senses, smell ranks fourth in importance for humans, although it is much more pronounced in other animals. Bloodhounds, for example, can smell an odor a thousand times weaker than humans. Taste, considered the fifth sense, is mostly the smell of food in the mouth. The sense of smell originates from the first cranial nerves (the olfactory nerves), which sit at the base of the brain's frontal lobes, right behind the eyes and above the nose. Inhaled airborne chemicals stimulate these nerves.
There are other aberrations of smell beside a decrease. Smells can be distorted, intensified, or hallucinated. These changes usually indicate a malfunction of the brain.

Causes and symptoms

The most common cause of anosmia is nasal occlusion caused by rhinitis (inflammation of the nasal membranes). If no air gets to the olfactory nerves, smell will not happen. In turn, rhinitis and nasal polyps (growths on nasal membranes) are caused by irritants such as allergens, infections, cigarette smoke, and other air pollutants. Tumors such as nasal polyps can also block the nasal passages and the olfactory nerves and cause anosmia. Head injury or, rarely, certain viral infections can damage or destroy the olfactory nerves.


It is difficult to measure a loss of smell, and no one complains of loss of smell in just one nostril. So a physician usually begins by testing each nostril separately with a common, non-irritating odor such as perfume, lemon, vanilla, or coffee. Polyps and rhinitis are obvious causal agents a physician looks for. Imaging studies of the head may be necessary in order to detect brain injury, sinus infection, or tumor.


Cessation of smoking is the first step. Many smokers who quit discover new tastes so enthusiastically that they immediately gain weight. Attention to reducing exposure to other nasal irritants and treatment of respiratory allergies or chronic upper respiratory infections will be beneficial. Corticosteroids are particularly helpful.

Alternative treatment

Finding and treating the cause of the loss of smell is the first approach in naturopathic medicine. If rhinitis is the cause, treating acute rhinitis with herbal mast cell stabilizers and herbal decongestants can offer some relief as the body heals. If chronic rhinitis is present, this is often related to an environmental irritant or to food allergies. Removal of the causative factors is the first step to healing. Nasal steams with essential oils offer relief of the blockage and tonification of the membranes. Blockages can sometimes be resolved through naso-specific therapy-a way of realigning the nasal cavities. Polyp blockage can be addressed through botanical medicine treatment as well as hydrotherapy. Olfactory nerve damage may not be regenerable. Some olfactory aberrations, like intensified sense of smell, can be resolved using homeopathic medicine.


If nasal inflammation is the cause of anosmia, the chances of recovery are excellent. However, if nerve damage is the cause of the problem, the recovery of smell is much more difficult.



Fauci, Anthony S., et al., editors. Harrison's Principles of Internal Medicine. New York: McGraw-Hill, 1997.

Key terms

Allergen — Any substance that irritates only those who are sensitive (allergic) to it.
Corticosteroids — Cortisone, prednisone, and related drugs that reduce inflammation.
Nasal polyps — Drop-shaped overgrowths of the nasal membranes.
Rhinitis — Inflammation and swelling of the nasal membranes.


absence of the sense of smell. adj., adj anosmat´ic, anos´mic.


(an-oz'mē-ă), [MIM*301700]
Loss or absence of the sense of smell. It may be: general to all odorants (total), partial to some odorants, or specific to one or more odorants; due to transport disorders (in nasal obstruction) or sensorineural disorders (affecting the olfactory neuroepithelium or the central olfactory neural pathways); or hereditary or acquired. Recent studies indicate it is often the first sensory loss directly related to Alzheimer disease.
[G. an- priv. + osmē, sense of smell]


/an·os·mia/ (an-oz´me-ah) lack of sense of smell.anos´micanosmat´ic


Loss of the sense of smell.

an·os′mic adj.


Etymology: Gk, a + osme, without smell
a loss or an impairment of the sense of smell. It can occur as a temporary condition when a person has a head cold or respiratory infection or when intranasal swelling or other obstruction prevents odors from reaching the olfactory region. It becomes permanent when the olfactory neuroepithelium or any part of the olfactory nerve is destroyed as a result of intracranial trauma, neoplasms, or disease, such as atrophic rhinitis or the chronic rhinitis associated with the granulomatous diseases. In some instances, the condition may be caused by psychological factors, such as a phobia or fear associated with a particular smell. Kinds of anosmia include anosmia gustatoria and preferential anosmia.Also called anosphresia,olfactory anesthesia. anosmatic, anosmic, adj.


Absence of the sense of smell, a symptom typical of frontal lobe brain tumours.

Anosmia types 
▪ Nasal—Odorants do not reach the olfactory receptors. 
▪ Olfactory —Destruction of receptors or axons.  
▪ Central—Olfactory pathway problems.


Anosphrasia, olfactory anaesthesia Absence of the sense of smell, a symptom typical of frontal lobe brain tumors


Loss of the sense of smell. It may be due to lesion of the olfactory nerve, obstruction of the nasal fossae, or functional, without any apparent causative lesion.
[G. an- priv. + osmē, sense of smell]


Loss of the sense of smell. This often results from injury to the delicate fibres of the OLFACTORY NERVE as they pass through the bone above the nose (the cribriform plate).


n the inability to smell; may be short-term, selective (only affecting certain aromas), or total and permanent.


(an-oz'mē-ă) [MIM*301700]
Loss or absence of the sense of smell.
[G. an- priv. + osmē, sense of smell]


absence of the sense of smell; characteristic of lesions of the olfactory lobe, peduncle or mucosa. Such deficiencies are difficult to assess in animals.
References in periodicals archive ?
Caracterizacion de la serie y resultados del tratamiento endonasal endoscopico extendido transcribiforme a los meningiomas del surco olfatorio Cantidad de pacientes n = 12 Edad Promedio 52,6 anos Relacion sexo F/M 1/1 Forma clinica de presentacion Cefalea (91,6%), Anosmia (50%), Trastornos Neuropsicologicos (100%), Convulsiones (58%) Evaluacion Neuropsicologica Trastornos de Memoria: Pre (91,6%), Pre y Postquirurgico Post (50%) (3 meses) Trastornos de Atencion: Pre (100%), Post (41.
Clinical signs Benign Malignant Inflammatory/ (n = 435) (n = 128) non-neoplastic (n = 47) Unilateral nasal 308 83 12 obstruction Epistaxis/bloody 21 98 4 discharge Nasal mass 24 28 8 Sinusitis 193 9 21 Bilateral nasal 11 35 4 obstruction Headache 28 84 34 Diplopia 7 17 0 Facial numbness 7 75 7 Facial swelling/ 5 42 2 deformity Anosmia 5 18 1 Proptosis 0 6 0 Cervical 0 16 0 lymphadenopathy Table 2: Spectrum of benign sinonasal tumors (n = 435).
De acordo com a classificacao do olfato no teste, 24(50,0%) laringectomizados apresentaram anosmia, 22(45,8%) algum tipo de microsmia e apenas 2(4,2%) tiveram o olfato considerado dentro da normalidade.
What happens in a condition like anosmia is that the olfactory nerves are damaged or dead.
org SMELL Smelling disorders are mainly to do with the loss of the sense of smell, which is known as Anosmia.
Secondary symptoms such as anosmia, ear fullness, headache and cough may support the diagnosis.
Scientists funded by the National Institutes of Health have restored the ability to smell in a mouse model of a human genetic disorder that causes congenital anosmia -- the inability to smell from birth.
Success rates of up to 80%2 have been reported; however, there is additional morbidity related to the craniotomy as well as the risk of anosmia owing to damage to the olfactory tracts.
The plaintiffs alleged that the manufacturer's failure to reveal reports that linked Zicam to anosmia (the loss of smell) was a material omission.
Anosmia can be temporary when it is caused by a stuffy nose or a sinus infection, for example.
Prior to that, investors say Matrixx had touted the business success and safety of Zicam in the media and in response to some reports of anosmia in Zicam users and a handful of related product liability lawsuits.