Letter B
Brain fog
Also known as: Mental fog, Cloudy thinking
Brain fog symptom guide: what it can mean, possible causes, and when to seek care. Educational only.
Overview
Brain fog is not one disease but a feeling that thinking is heavy. It can follow poor sleep, stress, infection, or hormone changes. If it persists, assessment can look for treatable causes.
Possible causes
- Lack of sleep
- Mental stress
- After infections (e.g. COVID-19)
- Nutrient deficiency
- Certain medicines
When to see a doctor
Talk with a clinician if brain fog lasts, blocks work, or comes with severe headache or confusion.