Methods	Multicentre, randomised, double-blind, placebo-controlled, cross-over. Single dose to treat each of 4 consecutive attacks (3 with sumatriptan, 1 with placebo) Medication administered when migraine headache pain was of moderate or severe intensity Assessments at 0.5, 1, and 1.5 h after dosing Rescue medication available after 1.5 h
Participants	Aged 18 years or over, meeting IHS criteria for migraine (1988) with or without aura. At least 1-year history of migraine (untreated severity ≥ moderate) No ergotamine or analgesics containing opioid derivatives within 24 h, or simple analgesics or antiemetics within 6 h of taking study medication Each treatment separated by a pain-free interval of at least 24 h N = 170 (of which 120 treated all 4 attacks) M 15, F 155 (91%) Mean age 41 years Proportion with/without aura not reported
Interventions	Sumatriptan 6 mg, n = 166 (128 treating first attack with moderate or severe baseline pain intensity) Placebo, n = 144 (42 treating first attack with moderate or severe baseline pain intensity)
Outcomes	Headache relief (at 1 h) Pain-free (at 1 h) 24 h sustained headache relief 24 h sustained pain-free Improvement in nausea, vomiting, photophobia, and phonophobia at 1 h Improvement in functional disability at 1 h Use of rescue medication Adverse events Withdrawals
Notes	Oxford Quality Score: R1, DB2, W1. Total = 4.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding (performance bias and detection bias) All outcomes	Low risk	Placebo injections designed to match the active dose
Study size	High risk	Treatment group 50 to 200 participants, placebo group < 50 participants