Methods	Multicentre, randomised, double-blind, placebo-controlled, double-dummy, three-period, cross-over. Single oral dose of each treatment for each of three migraine attacks Assessments at 0 and 2 hours. If pain not controlled, participants asked to wait 2 hours before taking rescue medication
Participants	Aged 18-65 years, meeting IHS criteria for migraine without aura. At least 12-month history of migraine, with age of onset before 50 years and two to six attacks permonth. Prophylaxis permitted if stable for ≥ 2 months Excluded participants with other types of headache. Included participants with ‘slight’ migraine at baseline, but reported primary outcomes for those with ≥ moderate pain separately N = 247 (198 treated three attacks and analysed for efficacy) M = 57, F = 190 Mean age = 40 years 36.8% of randomised participants were taking prophylactic therapy
Interventions	Aspirin 1000 mg, n = 198 Acetaminophen 400 mg plus codeine 25 mg, n = 198 Placebo, n = 198
Outcomes	Headache relief at 2 hours Pain-free at 2 hours PI: 100 mm VAS Mean PID at 2 hours (from baseline) Relief of nausea and vomiting Use of rescue medication Patient preference for medication Adverse events
Notes	Oxford Quality Score: R1, DB2, W1. Total = 4
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	Not described
Allocation concealment?	Unclear	Not described
Blinding? All outcomes	Yes	Double-dummy design