We encountered two patients with sumatriptan-induced reversible cerebral vasoconstriction syndrome (RCVS). The present patients were taking sumatriptan for the first time because they had been tentatively diagnosed with a migraine. On reviewing the literature, we found nine other cases of triptan-induced RCVS, predominantly among women aged 30 to 40 years. RCVS has been precipitated by triptan at the first ever use, after daily use, and even with long-term use at a normal dose. Patients with acute onset of severe headache should be thoroughly evaluated, and triptan should be administered appropriately. If triptan-induced RCVS is suspected, vascular imaging should be repeated after several days.