Chronic headache associated with a substance or its withdrawal

**Definition:** Chronic headache associated with a substance or its withdrawal is caused by use of, exposure to or withdrawal from a substance, and has a duration of more than three months. The pain occurs on at least 50% of the days during at least three months. The duration of pain per day is at least 2 hours.

**Long definition:** Chronic headache associated with a substance or its withdrawal is caused by use of, exposure to or withdrawal from a substance, and has a duration of more than three months. The pain occurs on at least 50% of the days during at least three months. The duration of pain per day is at least 2 hours. Potential etiologies include exposure to a substance (e.g., Nitrous oxide) and substance withdrawal (caffeine, estrogen, and other substances with long-term use). Diagnostic Criteria Conditions A to D are fulfilled: A. Headache for >2 hours on ≥15 days per month for longer than 3 months. B. A substance or its withdrawal scientifically documented to be able to cause headache has been used. C. Evidence of a causal link between substance use/withdrawal and headache has been demonstrated by at least two of the following: C.1 Headache has developed in temporal relation to the onset of the use or withdrawal of a substance. C.2 One or both of the following is fulfilled: a) Headache has significantly worsened in parallel with worsening of the use or withdrawal of a substance. b) Headache has significantly improved in parallel with improvement of the use or withdrawal of a substance. C.3. Headache has characteristics typical for the use and withdrawal of a substance. C.4. Other evidence exists of causation D. The pain is not better accounted for by another diagnosis.

**Exclusions:** - Medication-overuse headache