Mehlisch 1998.

Methods	R, DB, PC, parallel‐group study 1 episode treated with a single dose of study medication when pain was ≥ mod intensity
Participants	Episodic tension headache (IHS), 1‐10 episodes/month Excl: pregnancy/lactating; history of other headache types; significant medical history; chronic analgesia use; drug dependence; hypersensitivity to study medications n = 737 randomised, 703 took medication (631 in analysis) M 201, F 430 Mean age 32 years Baseline pain 88% mod, 12% severe
Interventions	Paracetamol 1000 mg, n = 174 (166) Ketoprofen 12.5 mg, n = 181 (158) Ketoprofen 25 mg, n = 176 (156) Placebo, n = 172 (151) Rescue medication allowed after 2 h
Outcomes	PI: 4‐point scale over 4 h PR: 5‐point scale over 4 h Meaningful relief. Functional impairment. Patient global AEs
Notes	Oxford Quality Score: R1, DB2, W1
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Details of randomisation method not reported
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double dummy method
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double dummy method
Incomplete outcome data (attrition bias) All outcomes	Low risk	WOCF for withdrawals, LOCF for other, linear interpolation for missing points
Size	Unclear risk	50‐200 participants per treatment arm (151‐166)