Frame 1986.

Methods	R, DB, single oral dose, parallel groups Medication administered when baseline pain reached a moderate to severe intensity Assessed at 0, 1, 2, 3, 4, 5 h
Participants	Surgical removal of impacted third molar N = 135 M/F "balanced" but numbers not provided Mean age 24 years
Interventions	Ibuprofen 200 mg + codeine 15 mg, n = 32 Ibuprofen 400 mg + codeine 30 mg, n = 26 Ibuprofen 800 mg + codeine 60 mg, n = 26 Aspirin 600 mg, n = 25 Placebo n = 26
Outcomes	PI: non‐standard 9‐point scale PR: standard 5‐point scale Global assessment (no scale reported) Use of rescue medication Adverse events Withdrawals
Notes	Oxford Quality Score: R = 1, DB = 2, W = 1. Total = 4/5 Rescue medication (paracetamol) allowed after 2 h
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Low risk	Sealed sachets
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"aspirin specially formulated to match the other drugs"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"aspirin specially formulated to match the other drugs"
Size	High risk	< 50 participants per treatment arm