What should you know about intermittent loss of smell?

Your sense of smell may fade when a blocked or swollen nose prevents scent molecules from reaching smell-sensing tissue. Allergic rhinitis can cause congestion that comes and goes, while a common cold may temporarily alter smell during an infection. Chronic sinusitis can cause longer-lasting inflammation, pressure, discharge, or reduced smell. COVID-19 can affect smell during illness, and some people notice ongoing or returning changes afterwards, sometimes called Long COVID.

Notice whether the change affects both nostrils, whether it follows congestion, and whether smells seem weaker, distorted, or absent. A change in taste may actually be reduced smell, because flavour depends heavily on scent. Intermittent symptoms do not identify one cause on their own.

Keep a brief record of when smell changes, how long each episode lasts, nasal symptoms, recent infections, new medicines, and possible irritants such as smoke. Treating a known allergy or cold according to professional advice may improve nasal airflow. Avoid putting unprescribed oils or chemicals inside the nose, and do not use decongestant sprays for longer than their label advises.

Arrange a routine appointment if episodes keep returning, last beyond a recent cold, affect eating or safety, or occur without congestion. A clinician may examine the nose and mouth, review medicines and illness history, and decide whether further testing is needed. Until smell returns reliably, check food dates and use working smoke and gas alarms rather than relying on smell.

Seek urgent medical help for loss of smell with trouble breathing, swelling of the face or throat, severe headache, confusion, weakness, or other sudden neurological changes. Prompt assessment is also sensible after a head injury, or when symptoms include high fever, severe facial pain, swelling around an eye, or rapidly worsening illness.

Contact a clinician soon if the change is one-sided, accompanied by persistent bloody discharge, recurrent nosebleeds, or new visual symptoms. These features do not establish a diagnosis, but they need an examination. Do not drive or work around hazards if you cannot detect smoke, gas, spoiled food, or other warning odours.

Ask: Could nasal swelling, an allergy, sinus inflammation, infection, or a medicine explain the pattern? Does the examination suggest testing or referral? What should I do if smell becomes distorted or disappears completely? How can I protect myself from hazards while it is changing?