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Smell - impaired

Definition

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

Alternative Names

Loss of smell; Anosmia

Considerations

The loss of smell can occur as a result of nasal congestion or blockage of the nose and isn't serious, but it can sometimes be a sign of a nervous system (neurological) condition.

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

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

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:

• Alzheimer's dementia
• Disorders of the endocrine system
• Head trauma
• Nervous disorders
• Nutritional disorders
• Tumors of the head or brain

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

The sense of smell also enhances your ability to taste. Many people who lose their sense of smell also complain of a loss of the sense of taste. Most can still tell between salty, sweet, sour, and bitter tastes, which are sensed on the tongue. They may not be able to tell between other flavors. Some spices (such as pepper) may affect the nerves of the face and may be felt rather than smelled.

Common Causes

• Use of certain medications (such as amphetamines, estrogen, naphazoline, phenothiazines, prolonged use of nasal decongestants, reserpine, and possibly zinc-based products)
• Head injury
• Lead poisoning
• Nasal or sinus surgery or disease
• Natural aging process
• Radiation therapy
• Recent viral upper respiratory infection
• Tracheostomy
• Tumors of the nose or brain

Home Care

Treating the cause of the problem may correct loss of the sense of smell. Treatment can include:

• Antihistamines (if the condition is related to allergy)
• Changes in medication
• Surgery to correct blockages
• Treatment of other disorders

Avoid using too many nasal decongestants, which can lead to recurring nasal congestion.

If you lose your sense of smell, you may have changes in taste. But, adding highly seasoned foods to your diet can help stimulate the taste sensations that you still have.

Improve your safety at home by using smoke detectors and electric appliances instead of gas ones. You may not be able to smell gas if there is a leak. Or, install equipment that detects the presence of gas fumes in the home.

There is no treatment for loss of smell due to aging.

If you have a loss of smell due to a recent viral upper respiratory infection, be patient. The sense of smell may return to normal without treatment.

Call your health care provider if

Call your health care provider if the loss of smell continues, is getting worse, or if you have other unexplained symptoms.

What to expect at your health care provider's office

The doctor will perform a physical exam and ask questions about your medical history and current symptoms. Questions may include:

• Time pattern
  • When did this problem develop?
  • Have you always had problems with your sense of smell?
  • Is the problem 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 do you take?
• Other
  • What other symptoms do you have?

The doctor will look at your nose and surrounding structures. Tests that may be performed include:

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

In some cases, surgery (biopsy) to remove a piece of the cells responsible for smell (olfactory epithelium) may be needed to make a diagnosis.

If the loss of sense of smell is caused by a stuffy nose (nasal congestion), decongestants or antihistamines may be prescribed.

A vaporizer or humidifier may prevent mucus from drying and improve nasal discharge.

Steroid nasal sprays or pills may be recommended.

Vitamin A may be given by mouth or with a shot (injection).

References

Leopold DA, Holbrook EH. Physiology of olfaction. In: Cummings CW, Flint PW, Haughey BH, et al, eds. Otolaryngology: Head & Neck Surgery. 4th ed. Philadelphia, Pa: Mosby Elsevier; 2005:chap 37.

Lafreniere D, Mann N. Anosmia: Loss of smell in the elderly. Otolaryngol Clin North Am. 2009 Feb 1;42(1):123-131.