Sunshine 1996.

Methods	Single‐centre, randomised, double‐blind, placebo‐controlled, parallel‐group study Single oral dose administered after the onset of severe pain Duration: 6 h, with assessments at baseline, 0.5, 1, 2, 3, 4, 5, and 6 h post dose
Participants	Postepisiotomy pain Participants aged 18 years or older N = 305 (302 for efficacy) All F Mean age 24 years
Interventions	Ibuprofen 100 mg + caffeine 100 mg, n = 50 Ibuprofen 100 mg, n = 51 Ibuprofen 200 mg + caffeine 100 mg, n = 50 Ibuprofen 200 mg, n = 50 Ibuprofen 50 mg, n = 51 Placebo, n = 50 No medications that might confound the interpretation of efficacy, or caffeine‐containing food and beverages were permitted during the 6 h before and after dosing
Outcomes	PI: standard 4‐point scale PR: standard 5‐point scale PGE: 4‐point categorical scale (0 = poor, 1 = fair, 2 = good, 3 = excellent) Withdrawals and dropouts Serious adverse events
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	Method used to generate random sequence not described
Allocation concealment (selection bias)	Unclear risk	Method not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"All medications were dispensed as capsules"
Size	High risk	All relevant treatment groups borderline at 50 or 51 participants each