Ageusie

Ageusia is the complete loss of the sense of taste. It involves an inability to perceive the basic tastes—sweet, sour, salty, bitter, and umami—even when the tongue and oral mucosa are healthy. Because flavor also depends on smell, people with ageusia may describe meals as tasteless or flat.

Causes are diverse and may be congenital or acquired. Acquired ageusia often results from damage to taste receptors, the gustatory nerves (including branches of the facial, glossopharyngeal, and vagus nerves), or brain regions that interpret taste. Infections (notably severe viral infections), head or neck trauma, stroke, tumors, and neurological disorders are common contributors. Nutritional deficiencies (especially zinc), medications (such as chemotherapy, certain antibiotics, and anticonvulsants), smoking, and alcohol can also play a role.

Diagnosis relies on history and taste testing, with tests that present controlled solutions to evaluate each basic taste. Neurological examination may be used to assess cranial nerves involved in gustation (facial VII, glossopharyngeal IX, and vagus X). Clinicians differentiate ageusia from hypogeusia and dysgeusia, and from loss of smell, which can mimic taste changes.

Management targets the underlying cause when possible. Many cases improve after resolution of infection or nerve injury. Zinc supplementation may help in deficiency, and medication changes can resolve drug-induced ageusia. Dietary counseling and nutritional monitoring aid those with persistent loss. There is no specific cure for irreversible cases, though ongoing research explores gustatory rehabilitation and supportive therapies.

Prognosis varies. Some individuals regain taste over weeks to months, while others experience prolonged or permanent ageusia due to irreversible nerve damage or chronic disease. Early identification of reversible causes improves outcomes.