Loss of Taste and Smell: Causes Beyond COVID

Since 2020, losing your sense of smell has been treated as a COVID test in itself. It is not. Smell loss has been a common medical complaint for decades, and there are several causes worth ruling out before assuming a viral cause.

First: it is almost always smell, not taste

Your tongue detects five basic qualities: sweet, salty, sour, bitter, and savory. Everything else you think of as flavour — coffee, strawberry, garlic, cinnamon — comes from smell receptors detecting aromas that travel up from the back of your throat as you chew.

So when food tastes like cardboard but you can still tell salt from sugar, your taste is fine. Your smell is the problem. True taste loss is rare and usually points to a nerve issue or medication effect.

Causes to consider

Nasal blockage

The most common cause overall. If odour molecules cannot physically reach the smell receptors high in your nose, you cannot smell. Swelling from a cold, allergies, chronic sinus inflammation, or nasal polyps all do this. The reassuring feature: it comes back when the swelling settles.

Viral infection

COVID is one of several viruses that damage smell receptors directly. Common colds and flu do it too — this was well documented long before 2020. Most people recover within a few weeks; a minority take months.

Nasal polyps

Soft growths in the nasal passages, often linked to chronic sinus inflammation or asthma. Clue: gradual loss over months, persistent congestion on one or both sides, and a permanently blocked feeling. Treatable, but needs diagnosis.

Medications

A number of common drugs affect smell or taste, including some blood pressure medications, certain antibiotics, some antidepressants, and chemotherapy agents. Zinc nasal sprays specifically have been linked to smell loss and should be avoided.

Head injury

Even a moderate blow to the head can shear the delicate nerve fibres running from the nose to the brain. Loss is usually immediate and can be permanent.

Smoking and vaping

Progressive dulling of smell over years. Partially reversible after quitting.

Age

Smell declines naturally from around age 60, and quite noticeably after 70. This is normal but often mistaken for a new problem.

Neurological conditions

Gradual smell loss can be an early feature of Parkinson’s disease and some forms of dementia, sometimes preceding other symptoms by years. This is a reason to mention unexplained gradual smell loss to your doctor, not a reason to panic — the vast majority of cases have simpler explanations.

Sudden versus gradual: the most useful question

Smell training: the one intervention with real evidence

Smell training helps recovery after viral smell loss. It is simple and free.

Get four strong, distinct scents — the classic set is rose, lemon, clove, and eucalyptus, available as essential oils. Twice a day, sniff each one for about 20 seconds while concentrating on the memory of what it should smell like. Total time: about three minutes.

Do this for at least twelve weeks. Progress is slow and often not noticeable week to week, which is why most people quit too early. Studies show meaningful improvement in a significant proportion of people who complete the full course.

Safety point people overlook

Without smell, you cannot detect a gas leak, smoke, or spoiled food. If your smell loss is lasting, fit working smoke alarms and a natural gas detector, and go strictly by expiry dates rather than sniffing food.

When to see a doctor

Get evaluated if loss lasts more than four weeks after an infection clears, is gradual and unexplained, affects one nostril only, or comes with nosebleeds, facial pain, or vision changes.

Related reading

• Chills Without Fever in Adults: 9 Causes and When to Worry
• Sore Throat but No Fever: What It Actually Means
• Body Aches Without Fever: Causes and What Helps

Sources

• MedlinePlus Medical Encyclopedia — U.S. National Library of Medicine
• Centers for Disease Control and Prevention
• Over-the-Counter Medicines — MedlinePlus