Lost or changed sense of smell

A lost or changed sense of smell can affect how strongly you notice odours or how those odours seem to you. Complete loss is called anosmia. A reduced sense of smell is called hyposmia.

Some people can detect an odour, but it smells different or unpleasant. This is called parosmia. Smelling something that is not present is called phantosmia.

Smell depends on odour particles reaching specialised cells high inside your nose. These cells send messages to the brain. Congestion, inflammation, infection, injury, and several other conditions can disrupt this process.

Smell also provides much of food's flavour. Losing it can make meals seem bland even when your basic ability to taste sweet, salty, sour, bitter, and savoury foods remains.

You may notice that:

• familiar foods, perfumes, or household smells seem faint
• you cannot smell anything, even strong odours
• coffee, onions, smoke, or other familiar smells seem distorted
• pleasant smells seem burnt, rotten, chemical, or metallic
• an odour appears to be present when there is no clear source
• food has less flavour or your appetite changes

The change may be sudden or gradual. It may affect all smells or only certain ones. Some people also have a blocked or runny nose, facial pressure, sneezing, or other symptoms of a respiratory infection.

A smell change can affect safety and well-being. You may have trouble noticing smoke, leaking gas, spoiled food, or burning pans. Distorted smells may also make eating difficult.

Common causes include colds, influenza, COVID-19, and other viral respiratory infections. Nasal allergies can reduce smell by causing swelling and mucus. Nasal polyps—soft, non-cancerous growths inside the nose—can block airflow to the smell-sensing area.

Sinus inflammation may also affect smell, especially when it causes ongoing congestion, facial pressure, or nasal discharge.

Less common causes include a head injury, smoking, exposure to irritating chemicals, or side effects from some medicines. Do not stop a prescribed medicine on your own; ask the prescriber whether it could be contributing.

Smell can gradually weaken with age. Dental problems and previous nasal or sinus surgery may sometimes contribute. Certain conditions affecting the brain or nerves can also alter smell, but they usually cause other symptoms as well.

Rarely, persistent one-sided blockage, repeated nosebleeds, or neurological symptoms may point to a more serious cause that needs investigation.

Call emergency services if a sudden smell change occurs with signs of a stroke, such as facial drooping, weakness or numbness on one side, trouble speaking, confusion, loss of balance, or a sudden severe headache.

Seek urgent medical care after a significant head injury, especially if you also have worsening headache, repeated vomiting, unusual drowsiness, confusion, seizure, weakness, or clear fluid draining from the nose. Breathing difficulty after exposure to fumes or chemicals is also an emergency.

Arrange a routine appointment if:

• the change has no clear explanation
• it continues for several weeks after congestion or infection improves
• it keeps returning or is getting worse
• only one side of your nose seems blocked
• you have repeated nosebleeds, persistent facial pain, or unusual discharge
• the problem is affecting eating, weight, mood, or daily safety

If you develop a new respiratory illness, follow current local advice about COVID-19 testing and limiting contact with others.

A healthcare professional will ask when the change began, whether it was sudden, and whether it followed an infection, injury, new medicine, or chemical exposure. They may ask about congestion, allergies, sinus symptoms, smoking, taste changes, and neurological symptoms.

They may examine your nose, mouth, ears, and nervous system. A smell test may check whether you can identify or distinguish standard odours.

If the cause remains unclear, you may be referred to an ear, nose, and throat specialist. A small camera may be used to look deeper inside the nose. A CT or MRI scan is reserved for situations where symptoms or examination findings suggest a structural or neurological cause; many people do not need a scan.

Treatment depends on the cause. Smell often returns as swelling from a cold or allergy settles. If nasal inflammation or polyps are involved, a clinician may suggest appropriate treatment, such as a corticosteroid nasal spray. Antibiotics like amoxicillin or doxycycline do not treat viral infections and are only useful for certain bacterial infections.

Saline nasal rinses may help clear mucus and allergens. Use only distilled, sterile, or previously boiled and cooled water. Follow the device instructions and keep it clean.

Smell training may help some people with persistent loss or distortion, particularly after a viral infection. It involves regularly and gently smelling a small group of familiar scents over several months. A healthcare professional can explain how to do this safely.

While your smell is reduced:

• check that smoke and gas alarms work
• follow use-by dates and store food safely
• label leftovers with dates
• ask someone else to check food or possible gas leaks
• choose foods with appealing colours, textures, and temperatures

Avoid deliberately sniffing strong chemicals or essential oils at close range. Do not place substances inside your nose unless advised by a healthcare professional.

Recovery depends on why your smell changed. Smell affected by short-term congestion may improve within days or weeks. Recovery after a viral infection can take weeks or months and may happen gradually.

During recovery, smells can seem distorted before they become more familiar. This can be frustrating, but it does not necessarily mean the problem is worsening.

Some changes after a major head injury, long-standing nasal disease, or damage to smell pathways can last longer or become permanent. Follow-up is worthwhile if there is no improvement, the cause is uncertain, or eating and emotional well-being are being affected.

Is a smell change always caused by COVID-19?

No. COVID-19 is one possible cause, but colds, allergies, sinus inflammation, nasal polyps, medicines, and injuries can also affect smell. Testing may be appropriate if you have a new respiratory illness or known exposure.

Why does food taste bland?

Much of what people call taste is actually aroma travelling from the mouth to the nose while eating. You may still detect basic tastes even when flavours are difficult to recognise.

Can smell return after being completely absent?

Yes. Recovery is possible, particularly after congestion or a viral infection, but the timing is difficult to predict. Improvement may be gradual.

Should I worry about phantom smells?

An occasional brief episode may not indicate an emergency. Book an appointment if phantom smells are new, persistent, recurring, or accompanied by headaches, seizures, confusion, or other neurological symptoms. Sudden neurological symptoms need emergency care.