Smell, impaired

Alternative names:

anosmia; loss of smell

Definition:

The loss or impairment of the sense of smell.

Considerations:

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, and nervous disorders.

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

Most people who lose the sense of smell can differentiate salty, sweet, sour, and bitter tastes. These tastes 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 sensed rather than smelled.

Common causes:

• natural aging process
• recent viral upper respiratory infection
• nasal decongestants (see Antihistamines and Decongestants - oral)
• lead poisoning
• drugs (such as amphetamines, estrogen, naphazoline, phenothiazines, prolonged use of nasal decongestants, reserpine)
• radiation therapy
• nasal or sinus surgery
• tracheostomy

Note: There may be other causes of an impaired sense of smell. This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of this symptom can include unlikely diseases and medications. Furthermore, the causes may vary based on age and gender of the affected person, as well as on the specific characteristics of the symptom such as quality, time course, aggravating factors, relieving factors, and associated complaints. Use the Symptom Analysis option to explore the possible explanations for an impaired sense of smell, occurring alone or in combination with other problems.