Togrul 2011.

Methods	Double‐blind, random allocation to IV paracetamol 30 min before surgery versus IV tramadol 20 min before end of surgery
Participants	Type of surgery: septo‐rhinoplasty Paracetamol group Entered/completing: 25/25 Age (mean, SD): 31.5 ± 11 Sex (male, %): 64 Tramadol group Entered/completing: 25/25 Age (mean, SD): 31.8 ± 10 Sex (male, %): 64
Interventions	Paracetamol infusion 1 g given 30 min before end of surgery IV tramadol given 30 min (in abstract written 20 min) before end of surgery, dose not stated. In abstract ‐ 1 mg/kg dose is mentioned.
Outcomes	Primary: Pain intensity on 10 cm VAS Secondary: Patient satisfaction, drug side effects, analgesic need
Source of funding	Not stated
Were treatment groups comparable at baseline?	Yes: age, sex, weight, duration of surgery, and anesthesia
Details of preoperative pain	Not reported
Notes	Postoperatively participants could take 500 mg oral paracetamol, up to 3 g/day, and if required, tramadol 0.5 mg/kg as IV bolus
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	No information
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Last paragraph of introduction states it was double‐blind but no additional details were provided
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants have completed
Selective reporting (reporting bias)	High risk	Objective state adverse effect and patient satisfaction investigation. Adverse effect not reported. Only nausea % in one group is reported, stating it is higher than in the other group, but no quantitative data. Patient satisfaction not reported.
Size	High risk	Fewer than 50 participants per arm of the study (25 paracetamol, 25 tramadol)