Smell - impaired

Impaired smell is a change in how you detect or recognise odours. Your sense of smell may be reduced, completely absent, or distorted. You may also notice smells that are not actually present.

The medical term for reduced smell is hyposmia. Complete loss is called anosmia. Parosmia means familiar things smell different or unpleasant, while phantosmia means smelling something without an outside source.

Smell contributes greatly to flavour. When it is impaired, food may seem bland even though you can still detect basic tastes such as sweet, salty, sour, bitter, and savoury.

Impaired smell is a symptom rather than a disease. It has many possible causes, including temporary nasal congestion, a recent infection, medication effects, or injury. The pattern and any other symptoms help narrow down the cause.

You may notice that perfume, coffee, food, smoke, or other familiar odours are weaker than usual. Some people cannot smell anything. The change may affect both nostrils or seem more noticeable on one side.

A distorted sense of smell can make foods, toiletries, or household products smell burnt, rotten, chemical, or otherwise unfamiliar. These sensations are real even when other people do not notice the same odour.

Other symptoms may offer clues. A blocked or runny nose, sneezing, facial pressure, or postnasal drip can point to inflammation in the nose or sinuses. Smell loss after a viral illness may continue after the other symptoms have cleared.

Because smell affects flavour, you may lose interest in food or add more salt or sugar than usual. Smell impairment can also make it harder to notice smoke, gas leaks, spoiled food, or burning cookware.

Common causes include:

• Viral respiratory infections, including colds, influenza, and COVID-19
• Nasal congestion or inflammation from allergies, sinusitis, or nasal polyps
• Smoking and exposure to irritating chemicals
• Age-related changes in the smell system
• Some medicines, although you should not stop a prescribed medicine without advice

A blocked nose can prevent odour molecules from reaching the smell receptors high inside the nasal cavity. In other cases, an infection may affect those receptors or the nerves carrying smell information to the brain.

Less common causes include a previous head injury, nasal surgery, a growth blocking one side of the nose, or a condition affecting the nervous system. Parkinson’s disease and Alzheimer’s disease can affect smell, but smell impairment alone does not mean that you have either condition.

Some people have had a reduced or absent sense of smell since birth. Occasionally, no clear cause is found.

A sudden change after a head injury needs prompt assessment. New smell impairment accompanied by weakness, facial drooping, trouble speaking, severe confusion, or a sudden severe headache may signal a neurological emergency rather than a routine smell disorder.

Call emergency services if a sudden smell change occurs with:

• Facial drooping, arm or leg weakness, or difficulty speaking
• Severe confusion, collapse, or a sudden severe headache
• Significant head trauma, repeated vomiting, or increasing drowsiness
• Breathing difficulty or illness after smoke or chemical exposure

Arrange same-day medical advice for new smell loss after a head injury, even if the injury initially seemed minor. You should also seek prompt care for clear fluid draining from the nose after an injury.

Book a routine appointment if the change persists after a cold or nasal congestion has cleared, lasts for several weeks, keeps returning, or affects eating and daily safety. An appointment is also appropriate if you have one-sided nasal blockage, repeated nosebleeds, facial swelling, or worsening pain.

A brief change during a straightforward cold can usually be monitored at home. Follow current local advice about respiratory infection testing and reducing the spread of infection when relevant.

A healthcare professional will ask when the change began, whether it was sudden or gradual, and whether you recently had an infection, head injury, or chemical exposure. Mention nasal symptoms, distorted smells, medication changes, smoking, and whether one or both nostrils seem affected.

They may examine the inside of your nose for swelling, discharge, polyps, or another blockage. Simple smell tests use familiar odours to check how well you detect and identify scents.

If the cause remains unclear, you may be referred to an ear, nose, and throat specialist. A camera examination of the nasal passages, formal smell testing, or imaging may be considered when symptoms are one-sided, follow an injury, or suggest a structural or neurological cause. Scans are not needed for every case.

Treatment depends on the cause. Smell often improves as a cold or temporary nasal swelling settles. Allergy or sinus treatment may help when inflammation is blocking odours from reaching the smell receptors.

A clinician may suggest a corticosteroid nasal spray for certain inflammatory nasal conditions. These medicines do not work immediately and must be used correctly. Ask a pharmacist or clinician for advice rather than using someone else’s treatment.

Saline nasal rinses may help clear mucus and allergens. Use only sterile or distilled water, or water that has been boiled and allowed to cool. Clean the device according to its instructions.

Smell training involves regularly and attentively smelling a small set of distinct scents. It may help some people with smell loss after an infection or injury, although improvement can take time. A clinician or smell-disorder service can explain how to do it safely.

Do not stop prescribed medicines because you suspect a side effect. Ask the prescriber or a pharmacist to review them.

Protect yourself while your smell is impaired. Check that smoke and gas alarms work, label food with opening dates, and follow storage instructions rather than relying on smell to judge safety. Avoid deliberately smelling strong chemicals or putting substances inside your nose.

Recovery depends on what caused the change. Smell related to simple congestion may return over days as the nose clears. Recovery after a viral infection or head injury may take weeks or months and may be incomplete.

Distorted smells can appear during recovery. This can be upsetting, especially when it affects food, but it does not necessarily mean the condition is worsening.

Keep track of gradual changes and any new symptoms. Follow-up is useful if smell does not improve, distortion makes eating difficult, or reduced appetite leads to unintended weight loss.

Is impaired smell the same as losing taste?

No. Much of what people call taste is actually flavour created by smell. You may still recognise sweet, salty, sour, bitter, and savoury tastes while food seems flavourless.

Can COVID-19 still cause smell changes?

Yes. COVID-19 can cause reduced, absent, or distorted smell, sometimes without marked nasal blockage. Other viral infections can cause similar symptoms.

Can smell impairment be permanent?

Sometimes, particularly after serious injury or damage to smell pathways. However, many people improve, and recovery may continue for months.

Should I take supplements?

No supplement reliably treats every cause of impaired smell. Some products can cause harm or interact with medicines. Discuss supplements with a pharmacist or clinician before using them.

Can I test my smell at home?

You may notice changes using familiar, non-irritating household scents, but this does not identify the cause or replace formal testing. Never use ammonia, bleach, solvents, or other hazardous chemicals.