Why have I lost my sense of taste?

Your tongue detects only five basic tastes: sweet, salty, sour, bitter and savory (umami). Everything else you think of as flavor, such as strawberry, coffee or garlic, depends on smell. The Merck Manual explains that most people who lose their sense of smell can still taste salty, sweet, sour and bitter but cannot tell specific flavors apart, so they complain of lost taste. The NIDCD agrees that most people who think they have a taste disorder actually have a smell problem.

A simple check: if you can still tell that sugar is sweet and salt is salty but food has no flavor, the problem is probably smell.

• Hypogeusia - a reduced ability to taste. Much more common than total loss.
• Ageusia - complete loss of taste. Cleveland Clinic says it affects about 1 or 2 in 1,000 people.
• Dysgeusia - a distorted taste, such as metallic or rotten. Often happens during recovery from an infection.

1. Infections. Colds, flu and COVID-19 (the CDC lists new loss of taste or smell as a COVID-19 symptom), plus sinusitis, nasal polyps, throat infections and salivary gland infections.
2. Aging. MedlinePlus notes taste often decreases after age 60, with salty and sweet usually lost first.
3. Medicines. MedlinePlus lists examples including some thyroid medicines and captopril; antibiotics and antihistamines are also common culprits.
4. Smoking, especially pipes and cigars.
5. Dry mouth and poor oral hygiene, which the NIDCD lists among causes.
6. Nerve injury. Head injury, ear or sinus surgery, wisdom tooth extraction and Bell's palsy, which the NHS lists with one-sided facial weakness and loss of taste.
7. Cancer treatment. Radiation to the head and neck and chemotherapy.
8. Nutritional deficiencies and other medical conditions, which Cleveland Clinic lists among causes of ageusia.

The NHS says lost or changed smell is not usually serious and may get better in a few weeks or months. It suggests rinsing the nose with salt water if an infection or allergy is the cause, and notes that a GP can check for sinusitis or nasal polyps, which may be treated with steroid nasal sprays. Smell training, regularly sniffing a set of strong scents, can help some people. Treating the underlying cause, such as an infection or a medicine side effect, often restores taste, according to the NIDCD.

While taste is reduced, keep your mouth clean and moist, and use herbs, spices, texture and temperature to make food more enjoyable rather than adding extra salt or sugar.

Taste and smell protect you. The NIDCD warns that people with taste loss may eat spoiled food, add too much salt or sugar, which matters if you have high blood pressure or diabetes, and may lose or gain weight. The NHS adds that losing smell makes it harder to notice gas leaks, fire or spoiled food, so check use-by dates, fit a smoke alarm and consider a gas detector.

The NIDCD notes an ear, nose and throat specialist usually diagnoses taste disorders. Testing measures the weakest concentration of a taste you can detect, often with a sip, spit and rinse method, along with a nose, mouth and dental exam and a review of medicines. Smell is usually tested too.