The sense of smell is made possible by nerve cells located in the nose. When stimulated by particular odors, these specialized cells transmit certain messages to the brain, which interprets the information in order to distinguish particular aromas. The sense of taste works in a similar manner, as nerve cells in the taste buds of the mouth and throat react to particular foods or beverages.
Both of these senses may be impaired by aging, illness, injury, and other factors. Smell and taste testing is performed to help determine the extent of any such sensory loss; this is done by measuring the lowest concentration of a test substance that you can detect and identify.
Purpose of the Smell and Taste Testing
- Smell testing is performed to detect smell disorders, including reduction in the ability to smell (hyposmia); total loss of smelling ability (anosmia); and smell distortion (dysosmia) such as perceiving a pleasant smell as being unpleasant.
- Taste testing is performed to detect taste disorders, including a reduction in the ability to taste (hypogeusia); total loss of tasting ability (ageusia); and persistent abnormal taste in the mouth (dysgeusia).
Who Performs It
- An otolaryngologist or another specially trained physician.
- If you are having difficulty tasting food, you may actually have a smelling disorder. Most taste problems are actually caused by a loss of smelling ability, since the flavor of foods is highly dependent on their aroma.
- Smelling and tasting disorders rarely occur together in the same individual.
Before the Smell and Taste Testing
- No special preparation is necessary before these tests.
What You Experience
- You will be asked to “scratch and sniff” a series of paper slips, and then to identify each odor from a list of possibilities.
- You may also be asked to compare certain of the smells, or to describe how the intensity of a smell grows when the concentration of a particular substance is strengthened.
- This test takes about 15 minutes.
- You will be asked to taste and then identify various substances, which cover the four basic taste sensations—sweet, sour, bitter, and salty.
- In some cases, you will sip a substance and spit it out, and then describe the taste.
- Alternatively, the test may involve applying different chemicals directly to specific areas of the tongue.
- You may also be asked to compare certain tastes, or to describe how the intensity of taste grows when the concentration of a particular substance is strengthened.
- This test takes about 10-20 minutes.
Risks and Complications
- There are no risks or complications associated with this test.
After the Smell and Taste Testing
- You are free to leave the testing facility and resume your normal activities immediately after the test is completed.
- Your doctor will assess the test results and determine whether your sense of taste or smell is impaired. If so, your medical history usually provides a clear explanation for the problem. Possible causes include serious upper respiratory or sinus infections, nasal polyps, certain medications, tobacco smoking, dental problems, previous radiation therapy for cancer of the head or neck, and traumatic injury to the head. In addition, a number of systemic disorders, such as diabetes, hypertension, and degenerative nerve conditions such as Parkinson‘s disease, may also lead to loss of taste or smell.
- Some cases of impaired smell or taste are treatable, while others are not. When treatment is possible, it is directed at the underlying cause of the disorder.
- In rare cases, further testing, such as a CT scan or an MRI of the head, is needed to determine the cause for a taste or smell disorder.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media