Aksakal 1997.

Study characteristics
Methods	Aim of study: to compare the efficacy and skin tolerance of metronidazole 1% cream and AZA 20% cream in the treatment of moderate to severe acne Design: parallel Unit of allocation: individuals Allocation: randomisation; no details of sequence generation methods Blinding: unclear Duration of trial (from recruitment to last follow‐up): not described Dropouts: none
Participants	Population description: moderate to severe AV Setting: not described Randomised number: 40 Age (years): average 19.2 (range 14 to 27) Sex (M/F): 2/18 in treatment group; 14/6 in control group Severity of illness: moderate to severe acne
Interventions	Name of treatment group: AZA n = 20 Description: AZA 20% Treatment period: 12 weeks Timing: twice‐daily Name of treatment group: metronidazole n = 20 Description: metronidazole 1% Treatment period: 12 weeks Timing: twice‐daily
Outcomes	Primary outcomes Participants' global self‐assessment of acne improvement (e.g. measured by a four‐point scale: excellent, good, fair, and poor). Authors did not report this outcome Withdrawal for any reason. No withdrawals Secondary outcomes Change in lesion counts (inflamed and non‐inflamed). Authors reported P value, week 12 Physicians' global evaluation of acne improvement. Authors did not report this outcome Minor adverse events (assessed as total number of participants who experienced at least one minor adverse event). Only mentioned but no usable data. Quality of life Authors did not report this outcome
Notes	Funding: not described
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Forty patients with only moderate to severe acne participated in this randomised, comparative study". Comment: no details of random methods was described
Allocation concealment (selection bias)	Unclear risk	No details of concealment were described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Forty patients...participated in...", "the study was completed with 40 patients". Comment: no missing outcome data
Selective reporting (reporting bias)	Unclear risk	Insufficient baseline data reported
Other bias	Low risk	No other potential bias identified