Headache occurring as an acute adverse event after occasional use of a medication taken for purposes other than the treatment of headache.

Diagnostic criteria:
  1. Any headache fulfilling criterion C
  2. One or more doses of medication have been taken for purposes other than the treatment of headache
  3. Evidence of causation demonstrated by both of the following:
    1. headache has developed within minutes to hours of intake
    2. headache has resolved within 72 hours after intake has ceased
  4. Not better accounted for by another ICHD-3 diagnosis.

8.1.9 Headache attributed to occasional use of non-headache medication has been reported as an adverse event after use of many drugs. The following are the most commonly incriminated: atropine, digitalis, disulfiram, hydralazine, imipramine, nicotine, nifedipine, nimodipine, sildenafil.

The headache characteristics are not very well defined in the literature, and probably depend on the drug, but in most cases headache is dull, continuous, diffuse and of moderate to severe intensity.