Taste and Smell Disorders

In the world today, if​ you suddenly experience the loss of taste and smell, your first reaction is probably concern about COVID-19. You may be surprised (and perhaps relieved) to find out there are other disorders that can cause those symptoms as well. About 90% of our sense of taste is mediated by our sense of smell, or olfaction. 

Even before the COVID pandemic, the loss of taste and smell affected millions of Americans each year.  The most common taste and smell disorders are (ordered most common to least common):

• Anosmia: total loss of smell
• Hyposmia: reduced ability to smell
• Hypogeusia: reduced ability to taste
• Ageusia: total loss of taste

Causes of Taste and Smell Disorders

While some individuals are born unable to taste or smell, for most people these symptoms are signs of other health problems. Possible causes include:

• Nervous system disease
• Illness (allergies or sinus/respiratory infection)
• Aging
• Smoking
• Head injuries
• Medications
• Exposure to certain chemicals
• Diabetes
• Obesity
• High blood pressure
• Poor nutrition

Symptoms of Taste and Smell Disorders

Those affected by loss of taste and smell experience symptoms on a spectrum, from reduced ability to taste or smell to total loss of taste and smell. Some people may experience the loss of all types of tastes/smells, while others may only lose specific flavors (sweet, sour, bitter or salty).

Individuals may also find that smells they typically enjoy, become extremely vile.

Diagnosing Taste and Smell Disorders

When you visit an ear, nose and throat (ENT) doctor (also known as an otolaryngologist) to discuss a taste and smell disorder, they will first conduct a physical exam to make sure the loss is not simply caused by conditions in the nasal passageway.

There are two categories of tests used to diagnose a taste and smell disorder.

• Threshold tests use solutions of various strengths to test how strong a sweet, sour, bitter or salty flavor must be for an individual to be able to recognize it.
• Odor tests present the patient with a set of smells that they are asked to identify. Diagnosis is dependent on successfully (or unsuccessfully) identifying the smells.

Treatment of Taste and Smell Disorders

The treatment for taste and smell disorders depends on the condition.

For example, allergy and sinus disease management would be recommended for those individuals with these conditions. Individuals will often regain taste and smell after appropriate medical management.

If the loss of taste and smell is due to medicine, the physician may choose to adjust the dosage or change the prescription entirely.

Smell rehabilitation or training in conjunction with counseling can be helpful for some individuals. 

COVID-19 and Loss of Taste and Smell

One of the most common symptoms of COVID-19 is the temporary inability to taste and smell. COVID-19 can cause swelling of the nasal tissue, leading to changes in smell. Recent evidence suggests that COVID-19 affects the supporting cells of the olfactory nerves.

In most cases, the olfactory nerves regain their function and the sense of smell returns.

When to See a Doctor about Loss of Taste or Smell

If you have reduced or complete loss of taste and smell, please contact your primary care doctor. You may be referred to an ENT specialist for a more comprehensive evaluation