Why does COVID cause loss of smell?

Odours reach specialised nerve endings high inside the nose. COVID-19 can irritate the tissue around this system and alter the supporting cells that help it work. Smell may become faint, disappear, or return in a distorted way, where familiar foods or scents smell unpleasant. Nasal congestion can contribute, but loss of smell can also occur without a blocked nose.

Taste may seem reduced because much of flavour depends on smell. You can often still detect basic tastes such as sweet, salty, sour and bitter, while food seems less detailed or enjoyable.

Protect yourself from hazards while smell is reduced: check food dates and appearance carefully, use working smoke alarms, and take extra care around gas or strong cleaning products. Keep eating regular, nourishing meals even if flavours feel muted. Choose foods with different temperatures and textures if that makes meals more appealing.

If recovery is slow, a clinician can review nasal symptoms and discuss whether repeated, gentle smell practice with familiar scents is appropriate for you. Do not put essential oils or other substances inside the nose unless a clinician has advised it.

Book a review when loss of smell persists, worsens, or affects eating and safety. Assessment is also worthwhile if you have recurrent facial pressure, a long-lasting blocked nose, nosebleeds, or symptoms that began without an infection. Seek urgent help for sudden neurological symptoms such as facial drooping, new weakness, confusion or difficulty speaking.

Could allergy, sinus inflammation or another nasal problem be contributing? Is smell training suitable for me? Which symptoms would mean I need an examination of my nose or a referral?