Ageusia

Lore & Background

Ageusia is defined as the loss of taste functions of the tongue, including the inability to detect sweetness, sourness, bitterness, saltiness, and umami. It is sometimes confused with anosmia, the loss of smell, but true ageusia is relatively rare. The condition can arise from a wide range of factors: damage to taste buds, radiation therapy, facial nerve damage from surgery, head traumas, infections such as sinusitis, strep throat, influenza, and COVID-19, as well as neurological conditions like epilepsy, stroke, multiple sclerosis, and diabetes. Certain medications, including muscle relaxants, chemotherapy drugs, and blood pressure medications, can also cause ageusia.

Reader's Guide

Ageusia gained significant attention during the COVID-19 pandemic, as it became a prominent symptom of infection. Studies indicate that ageusia was observed in 28.0% of COVID-19 patients, with hypogeusia in 33.5% and dysgeusia in 41.3%. In a European study of over 400 COVID-19 patients in April 2020, 88% reported gustatory dysfunction. The duration of ageusia recovery varies depending on the cause; for COVID-19, it can last up to 4 weeks and is influenced by viral variants, immune response, and demographic factors. Proposed mechanisms include the distribution of ACE2 receptors on taste cells and changes in saliva. Diagnosis is typically performed by an otolaryngologist using tests such as electrogustometry or edible strip taste tests. Treatment depends on the underlying cause and may involve discontinuing or switching medications, or using antihistamines, decongestants, or antibiotics. Complications include depression, social withdrawal, and unhealthy eating habits, which can be particularly risky for individuals with diabetes.

Did You Know?

• True ageusia is relatively rare compared to hypogeusia and dysgeusia.
• Ageusia can be an indication of a COVID-19 infection and may last up to 4 weeks.
• Zinc deficiency can lead to ageusia due to a shortage of zinc-binding proteins needed for taste bud growth.