Causes of loss of sense of smell

A common cold can temporarily block odour molecules from reaching the smell receptors. Allergic rhinitis can swell the nasal lining and add sneezing, itching, or watery discharge. Chronic sinusitis may cause ongoing congestion, facial pressure, thick drainage, and reduced smell. COVID-19 can affect smell during an infection, and Long COVID can involve symptoms that continue after the initial illness. Smell may be reduced, absent, or distorted; taste can seem weaker because flavour depends partly on smell. The symptom alone does not show which cause is present, so duration, nasal symptoms, recent infection, injury, and medicines are useful clues.

Keep smoke, chemical fumes, and spoiled food away from your nose while smell is reduced. Check smoke and gas alarms at home, and ask someone else to confirm food freshness. Saline nasal rinsing may ease congestion when appropriate, but use safe prepared water and follow product directions. Do not insert objects into the nose or use decongestant sprays for longer than advised. Arrange a review if smell does not return after a cold, repeatedly disappears, or affects eating and safety.

Seek prompt medical help for loss of smell after a head injury, or when it occurs with severe headache, confusion, weakness, or other neurological changes. Arrange an assessment for one-sided blockage, recurrent nosebleeds, facial swelling, severe pain, or symptoms that persist or worsen. A clinician can examine the nose, review medicines and infections, and decide whether further evaluation is needed.

Ask whether congestion, allergy, sinus inflammation, recent COVID-19, Long COVID, or another factor best fits the timing. Describe whether smells are absent or distorted and whether taste changed too. Ask about nasal treatments, safety measures at home, and when persistent symptoms should be reviewed again.