MedlinePlus Medical Encyclopedia: Smell

Skip navigation


Medical Encyclopedia
Other encyclopedia topics:	A-Ag Ah-Ap Aq-Az B-Bk Bl-Bz C-Cg Ch-Co Cp-Cz D-Di Dj-Dz E-Ep Eq-Ez F G H-Hf Hg-Hz I-In Io-Iz J K L-Ln Lo-Lz M-Mf Mg-Mz N O P-Pl Pm-Pz Q R S-Sh Si-Sp Sq-Sz T-Tn To-Tz U V W X Y Z 0-9

Smell - impaired

Contents of this page:
Alternative names Definition Considerations Common Causes	Home Care Call your health care provider if What to expect at your health care provider's office

Alternative names

Loss of smell; Anosmia

Definition Return to top

Impaired smell is the partial or total loss of the sense of smell.

Considerations Return to top

The loss of smell is usually an insignificant result of nasal congestion or obstruction, but it can sometimes indicate a neurological disorder. Loss of the sense of smell may be idiopathic (without any identifiable cause).

Some loss of smell occurs normally with aging. In most cases, there is no obvious or immediate cause, and there is no treatment.

Temporary loss of the sense of smell is common with colds and nasal allergies, such as hay fever (allergic rhinitis). It may occur following a viral illness.

The sense of smell is often lost with disorders that prevent air from reaching the part of the nose where smell receptors are located (the cribriform plate, located high in the nose). These disorders may include nasal polyps, nasal septal deformities, and nasal tumors.

Other disorders that may cause a loss of the sense of smell include tumors of the head or brain, head trauma, and a wide variety of endocrine, nutritional, Alzheimer's dementia, and nervous disorders.

Many medications may change or decrease the ability to detect odors.

Most people who lose the sense of smell can still differentiate salty, sweet, sour, and bitter tastes, which are sensed on the tongue. They may not be able to distinguish other flavors. Some spices (such as pepper) may stimulate facial nerves and may be felt rather than smelled.

Common Causes Return to top

Natural aging process
Recent viral upper respiratory infection
Nasal decongestants
Lead poisoning
Drugs (such as amphetamines, estrogen, naphazoline, phenothiazines, prolonged use of nasal decongestants, reserpine)
Radiation therapy
Nasal or sinus surgery
Tracheostomy
Nasal or brain tumors

Home Care Return to top

Treatment of underlying disorders may correct loss of the sense of smell. This can include antihistamines (if the condition is related to allergy), surgical correction of physical blockages, treatment of other disorders, changes in medication, and so on. Avoid excessive use of nasal decongestants, which can lead to recurring nasal congestion.

If loss of the sense of smell is permanent, dietary counseling may include use of highly seasoned foods and stimulation of taste sensations that remain.

Caution should be taken to ensure safety around the home with smoke detectors and use of electric appliances rather than gas appliances or technologies that detect the presence of gas fumes in the home.

For loss of smell due to aging, there is no treatment.

For loss of smell caused by a recent viral upper respiratory infection, be patient. The symptoms return to normal without treatment. Sometimes zinc supplements are recommended.

Note: Loss of the sense of smell may be temporary, and ability to smell may return spontaneously, especially after colds or viral infections.

Call your health care provider if Return to top

If the loss of smell is persistent, is getting worse, or is accompanied by other unexplained symptoms, call your health care provider.

What to expect at your health care provider's office Return to top

The medical history will be obtained and a physical examination performed.

Medical history questions documenting impaired sense of smell in detail may include:

Time pattern
- When did this problem develop?
- Have you always had problems with your sense of smell?
- Is it getting worse?
Quality
- Are all odors affected or only certain types?
- Can you taste food?
Aggravating factors
- Do you have a cold or other upper respiratory infection?
- Do you have allergies?
- Do you have chronic sinusitis?
- What medications are being taken?
Other
- What other symptoms are also present?

The physical examination will include a physical examination of nasal structures.

Diagnostic tests that may be performed include:

CT scan
Olfactory nerve testing
Nasal endoscopy
X-rays of the skull
MRI scan

Intervention:
If possible, the cause will be treated. If the loss of sense of smell is caused by nasal congestion, local decongestants or antihistamines may be prescribed. A vaporizer or humidifier may be recommended to prevent mucosal drying and improve nasal discharge.

Vitamin A may be given orally or by injection. In some cases, a biopsy of the olfactory epithelium (cells responsible for smell) may be required to make a diagnosis.

Update Date: 4/19/2004

Updated by: Kevin Fung, M.D., FRCS(C), Department of Otolaryngology - Head and Neck Surgery, University of Michigan Medical Center, Ann Arbor, MI. Review provided by VeriMed Healthcare Network.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2002 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.