Headache developing as an adverse event during hormone therapy is coded as 8.1.12 Headache attributed to exogenous hormone. Headache developing as a complication of long-term overuse of acute headache medication by a person with a headache disorder is coded as 8.2 Medication-overuse headache or one of its subtypes.
Headache developing as an adverse event during long-term use of a medication taken for purposes other than the treatment of headache, and not necessarily reversible.
A. Headache present on ≥15 days per month and fulfilling criterion C
B. Long-term use of a medication taken for purposes other than the treatment of headache
C. Evidence of causation demonstrated by at least two of the following:
1. headache has developed in temporal relation to the commencement of medication intake
2. one or more of the following:
a) headache has significantly worsened after an increase in dosage of the medication
b) headache has significantly improved or resolved after a reduction in dosage of the medication
c) headache has resolved after cessation of the medication
3. the medication is recognized to cause headache, in at least some people, during long-term use
D. Not better accounted for by another ICHD-3 diagnosis.
The dosage and duration of exposure that may result in headache during long-term use varies from medication to medication. Similarly, the time required for resolution varies – if the effect is reversible.
8.1.11 Headache attributed to long-term use of non-headache medication can be due to a direct pharmacological effect of the medication, such as vasoconstriction producing malignant hypertension, or to a secondary effect such as drug-induced intracranial hypertension. The latter is a recognized complication of long-term use of anabolic steroids, amiodarone, lithium carbonate, nalidixic acid, thyroid hormone replacement therapy, tetracycline and minocycline.