McQuay 1996.

Methods	Single‐centre, randomised, double‐blind, placebo‐controlled, parallel‐group study Single oral dose administered after onset of moderate or severe pain Duration: 8 h, with first 2 h in hospital. Time points of individual assessments not reported
Participants	Dental surgery: third molar removal N = 164 (161 for efficacy) M 59, F 102 Mean age 25 years
Interventions	Ibuprofen 200 mg + caffeine 50 mg, n = 30 for efficacy Ibuprofen 200 mg + caffeine 100 mg, n = 30 for efficacy Ibuprofen 200 mg + caffeine 200 mg, n = 29 for efficacy Ibuprofen 200 mg, n = 31 for efficacy Ibuprofen 400 mg, n = 30 for efficacy Placebo, n = 11 for efficacy No caffeine‐containing products from midnight on the evening before surgery and no other analgesics in the 12 h before surgery
Outcomes	PI: standard 4‐point scale, an 8‐word scale (randomly placed words ranging from 'no pain' to 'excruciating', scored 0 to 7), and a 100 mm VAS PR: standard 5‐point scale and a 100 mm VAS PGE: standard 5‐point scale Withdrawals and dropouts Serious adverse events
Notes	Oxford Quality Score: R2, DB2, W1. Total = 5/5
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised using a random number computer program
Allocation concealment (selection bias)	Low risk	Remote packaging, labelled only with treatment number
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"identical matching capsules"
Size	High risk	< 50 participants in relevant treatment arms