Smell and Taste Disorders 
(Chemosensory Disorders)

The senses of smell and taste are chemosenses and belong in the chemical sensing system. The processes of smelling and tasting are complex and begin when molecules are released by substances that stimulate the sensory cells in the nose, mouth or throat.

  • Olfactory nerve cells are found in tissue located high inside the nose and connect directly to the brain and are stimulated by odors.
  • Gustatory nerve cells are located in the taste buds of the mouth and throat and are stimulated by the taste of food and beverage.


These sensory cells transmit messages to the brain through the nerves, where specific tastes and smells are identified.


The four basic taste sensations are sweet, sour, bitter and salty. When these tastes, along with texture, temperature and information from the common chemical sense, combine with odors, the perception of flavor occurs. Flavor defines the food that is eaten, and is recognized mainly through the sense of smell. Chemosensory disorders are the loss of smell (anosmia) and the loss of taste (ageusia). Sometimes, a person experiences a reduced ability to smell (hyposmia) or taste sweet, sour, bitter or salty substances (hypogeusia). Other times, unpleasant odors, tastes or flavors may be mistaken for something that is normally pleasant to smell or taste.


Smell disorders are serious because they damage the early warning system that can alert a person to hazardous situations, such as fire, poisonous fumes, leaking gas, or spoiled food and beverages.


Abnormalities in taste and smell can indicate or accompany disease or other conditions, including the following:


Causes for Smell and Taste Disorders
Although some people are born with chemosensory disorders, most are caused by other factors such as:

  • Illness, such as upper respiratory or sinus infection
  • Injury to the head
  • Hormonal disturbances
  • Dental problems
  • Exposure to certain chemicals
  • Medication
  • Exposure to radiation therapy for head or neck cancer


Diagnosing Smell and Taste Disorders
Your physician will evaluate your complete medical history, conduct a physical examination and may request additional diagnostic procedures, which may include the following tests:

  • Measuring the lowest concentration of a chemical that can be recognized
  • 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


Treating Smell and Taste Disorders
There are several treatment options for smell and taste disorders:

  • Stopping or changing medications that contribute to the disorder
  • Correction of the medical problem that is causing the disorder
  • Surgical removal of obstructions that may be causing the disorder


Specific treatment for smell and taste disorders will be determined by your physician based on your individual needs and the following conditions: 

  • Age, overall health and medical history
  • Extent of the disease
  • Tolerance for specific medications, procedures or therapies
  • Expectations for the course of the disease
  • Your opinion or preference



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