Brain fog during COVID: what to know

You may lose your train of thought, struggle to find familiar words, forget an appointment or need more time to complete a task. Fever, poor sleep, dehydration, stress and fatigue can all make thinking harder while you are unwell. Difficulty concentrating is a recognised symptom during recovery, but it can also have other explanations such as iron deficiency anaemia, depression, anxiety, insomnia or obstructive sleep apnoea. Symptoms that continue after the infection deserve an assessment for Long COVID rather than self-diagnosis.

Keep a simple diary of sleep, activity, symptoms and tasks that feel difficult. Break work into short periods, take planned rests before exhaustion, and reduce switching between tasks. Use phone reminders, written lists and a quiet setting for demanding conversations. Drink regularly, eat routine meals and protect a consistent sleep schedule. Increase activity gradually only when your symptoms remain stable; pushing through a flare can leave you more depleted. A clinician can review medicines, sleep, mood and other health factors, then tailor a return-to-work or study plan.

Arrange a medical appointment if brain fog is worsening, lasts beyond the acute illness, interferes with driving or work, or comes with marked fatigue, low mood or sleep problems. Seek urgent help for sudden confusion, difficulty speaking, new weakness or numbness on one side, a seizure, fainting, severe breathlessness or chest pain. Do not drive or make high-stakes decisions if your attention is unreliable.

Ask which symptoms should be monitored, whether blood tests or a medication review are appropriate, and how to pace work or exercise. Tell the clinician when the change began, whether it fluctuates after activity, and how sleep and mood have changed.