There are no population-based prospective epidemiologic data on the incidence of substance-induced headaches, but certain substances have been studied (
4,
23,
62). The major study was the World Health Organization (WHO) Collaborating Centre for International Drug Monitoring of 27 countries that gathered 10,506 reports of drug-induced headaches from 1972 to 1987. Of these headaches, 9733 were unclassified headaches, 611 were migraine-type headaches or worsening of a pre-existing migraine, and 162 were due to intracranial hypertension. The 10 most reported drugs associated with headaches were indomethacin, nifedipine, cimetidine, atenolol, trimethoprim-sulphamethoxazole, zimelidine, glyceryl trinitrate, isosorbide dinitrate, zomepirac, and ranitidine. The majority of the drugs were nonsteroidal antiinflammatory drugs (NSAIDs), peripheral vasodilators, calcium channel blockers,
β-receptor blockers, histamine receptor blockers, or angiotensin-converting enzyme (ACE) inhibitors. Oral contraceptives were the most common cause of migraine. Other common precipitants of migraine-type headaches were atenolol, cimetidine, danazol, diclofenac, ethinylestradiol, indomethacin, nifedipine, and ranitidine. Tetracyclines, isotretinoin, and trimethoprim-sulphamethoxazole were the most frequently reported as causing intracranial hypertension (
61,
62,
63).