Indomethacin has consistently been proven to provide complete and sustained relief of symptoms in hemicrania continua (HC) and chronic paroxysmal hemicrania (CPH), but is not devoid of side-effects. The goal of this retrospective study is to assess the dose and side-effects of prolonged indomethacin treatment of HC and CPH. Twenty-six patients with either HC or CPH were followed during an average of 3.8 years after onset of treatment with indomethacin. Relief of symptoms occurred within 3 days of treatment, with 84 +/- 32 mg/day of indomethacin. With time, 42% of patients experienced a decrease of up to 60% in the dose of indomethacin required to maintain a pain-free state. Six (23%) patients showed adverse events, mostly gastrointestinal and relieved with ranitidine. No major side-effects were observed. These results indicate that prolonged indomethacin treatment of HC or CPH has a good safety and tolerability profile with a reduction of up to 60% in the initial dose.