Smell and Taste Disorders (Chemosensory Disorders)

What are smell and taste disorders?

The loss of the senses of smell ( anosmia) and taste ( ageusia) are the most common chemosensory disorders.

The reduced ability to smell ( hyposmia) or to taste sweet, sour, bitter or salty substances ( hypogeusia) are also common.

In other disorders of the chemosenses, odors, tastes, or flavors may be misread or distorted, causing a person to detect an unpleasant odor or taste from something that is normally pleasant to taste or smell. These disorders are important because they can have a significant impact on quality of life and be a sign of underlying disease.

Smell disorders are serious because they damage the early warning system that can alert a person to such things as:

Fire
Poisonous fumes
Leaking gas
Spoiled food and beverages

Abnormalities in taste and smell can accompany or indicate the existence of diseases or conditions such as:

Obesity
Diabetes
Hypertension
Malnutrition
Degenerative diseases of the nervous system such as:
- Parkinson's disease
- Alzheimer's disease

What causes smell and taste disorders?

Although some people are born with chemosensory disorders, most are caused by:

Illness (i.e., upper respiratory infection, sinus infection)
Injury to the head
Hormonal disturbances
Dental. oral, or perioral problems
Exposure to certain chemicals
Certain medications
Exposure to radiation therapy for head or neck cancer
Cigarette smoking

How are smell and taste disorders diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures may include:

Measuring the lowest concentration of a chemical that a person can recognize
Comparing tastes and smells of different chemicals
"Scratch and sniff" tests
"Sip, spit, and rinse" tests where chemicals are directly applied to specific areas of the tongue