Causes of loss of smell

The first question is whether air can reach the smell area high inside the nose. Colds, allergic rhinitis, chronic sinusitis, swelling and nasal polyps can block that route. In other cases, an infection may affect smell receptors or the nerves and brain pathways that process odours.

Timing provides useful clues: a sudden change after a head injury differs from gradual loss with long-standing nasal symptoms. New medicines, smoking and exposure to irritating chemicals can contribute. COVID-19 and other viral illnesses can affect smell, while ongoing symptoms may represent a slower recovery or a separate nasal problem.

Write down when the loss started, whether it is complete or reduced, and whether one side is worse. Record congestion, sneezing, facial pressure, altered smells, recent infections, injury, smoking and medicine changes. This history helps a clinician choose an examination and next step.

Avoid smoke and chemical fumes, and do not place unprescribed substances inside the nose. Protect yourself from hazards by checking alarms and dating food. Nasal treatment may help when blockage or inflammation is present, but the right option depends on your symptoms and health.

Get urgent help for smell loss with sudden weakness, speech difficulty, confusion, a severe new headache or other neurological symptoms. Seek prompt assessment after head injury, with breathing difficulty, severe facial swelling, high fever, or repeated nosebleeds.

Make a routine appointment for loss that persists, keeps returning, affects eating or safety, or has no clear trigger. A clinician may examine the nose and throat, review medicines and decide whether specialist assessment is needed.

Does the pattern suggest blockage, inflammation or a smell-pathway problem? Could my medicines, allergies, infection or injury be involved? What treatment is appropriate, and when should I return if smell has not improved?