Cognition and Fatigue
Brain Fog
Related terms · Mental cloudiness · Brain fog
Brain fog is a common term used to describe a feeling of mental cloudiness and finding it more difficult than usual to concentrate, remember, or find words.
Meaning and Distinctions
What is brain fog?
Brain fog is not a single diagnostic name. It involves changes following sleep issues, medication, anemia, thyroid problems, or infections, as well as depression, anxiety, Migraine· While keeping track of potential causes such as dizziness, specify exactly when your concentration, word-finding ability, and processing speed decline. Brain fog is a common term used to describe a feeling of mental cloudiness where concentration, memory, and finding words are more difficult than usual.
- Easily confused terms
- It is not a single definitive diagnosis; other physical causes such as sleep, medication, headaches, and anxiety must be examined together.
- Why this is checked during medical evaluation
- Brain fog is not a single diagnosis. While keeping track of potential causes such as changes following sleep, medication, anemia, thyroid issues, or infection, as well as depression, anxiety, migraines, or dizziness, specify exactly when your concentration, word-finding ability, and processing speed decline.
- What to note down for your visit
- Please record the following with dates and show them during your medical evaluation: specific moments where you felt stuck while finding words, reading, looking at a screen, or working; the clearest and cloudiest times of the day; sleep, diet, menstruation, medications taken, test results, and recovery time after dizziness or headaches.
Dizziness, Ear, Head, and Face Glossary
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Check guides where this term is used
- Condition GuideBrain fogRather than being a formal diagnosis, brain fog is a descriptive term for the experience of feeling mentally cloudy, thinking slowly, and finding concentration, memory, and word-finding more difficult than usual. It may appear alongside fatigue and sleep problems or follow an infection, but since various causes such as medication side effects, depression, anxiety, and thyroid issues are possible, the onset time and impact on daily life must be evaluated. If sudden severe confusion occurs or is accompanied by weakness on one side of the body or difficulty speaking, do not dismiss it as brain fog and seek emergency help immediately.→
- Medical Evaluation GuideWhat should I prepare before a consultation for dizziness, tinnitus, or headache?Write the first sensation you felt, the posture at onset, the duration, and any concurrent ear symptoms, headache, nausea, or heart rate changes on a single page. Please prepare your MRI, hearing test, nystagmus test, and ECG results along with your medication envelopes, and share what has improved and what remains after treatment. Rather than a perfect diary, recording three representative attacks and scenes that disrupt your daily life is more helpful.→
- Head, Ear, and Face ColumnWhen feeling foggy, dizzy, and having a headache, where does brain fog begin?→
Evidence and Update Information
The following materials were referenced to verify the basis and scope of the definitions and treatment descriptions.
- International Headache Society: ICHD-3International classification distinguishing migraines, tension-type headaches, chronic headaches, and secondary headaches