How does covid cause anosmia?

The smell-sensing area sits high inside the nose. During COVID-19, inflammation can alter the surrounding support cells and the local conditions needed for odour signals to reach the nervous system. A blocked or irritated nose may add to the difficulty detecting smells.

Some people notice reduced smell, complete loss of smell, or distorted odours. Taste can seem weaker because flavour depends heavily on smell, although basic taste sensations come from the tongue. COVID-19 is one possible cause; allergic rhinitis, a common cold and chronic sinusitis can also affect smell.

Take care around smoke, gas, spoiled food and other hazards that normally provide a smell warning. Check food dates visually and use working alarms. If congestion is present, discuss suitable treatment with a clinician rather than using nasal products repeatedly without advice.

Record when the change began and whether it followed respiratory symptoms. Arrange medical advice if the loss is marked, persistent, recurrent, or accompanied by facial pain, nasal blockage, neurological symptoms or concern about COVID-19. Some people with Long COVID experience continuing smell changes and may need structured assessment.

Seek urgent help for severe breathing difficulty, new confusion, weakness on one side, a severe sudden headache, a head injury, or swelling around the eye. Loss of smell alone is not usually an emergency, but sudden neurological symptoms need immediate assessment.

Ask whether the pattern suggests infection, nasal inflammation or another cause, and whether COVID-19 testing is appropriate. Discuss nasal treatment, smell training, follow-up timing and which warning signs should change the plan.