Schalen 1993.

Methods	Design: randomised, placebo‐controlled, parallel‐group trial
Participants	Number assigned: 106 adults (macrolide n = 53, placebo n = 53) Age in years (mean): macrolide: 33.6, placebo: 38.3 Setting: secondary care
Interventions	Indication: acute laryngitis Type of macrolide: erythromycin Route: per oral Dose per day: 1000 mg Duration of treatment: 5 days Total treatment dose: 5000 mg
Outcomes	Adverse events stated as an outcome in trial registration/protocol/paper: no Adverse events ascertainment: unclear Adverse events: not reported Antimicrobial resistance: not reported Death: not reported
Funding sources	Study supported by Abbott Scandinavia AB, Sweden.
Notes	Concomitant medication: unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Sequence generation not described.
Allocation concealment (selection bias)	Unclear risk	Allocation not described.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Identical‐appearing placebo
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants and clinicians blinded. No relevant outcome reported.
Incomplete outcome data (attrition bias) All outcomes	Low risk	7% dropout, unclear which group. Reasons given.
Selective reporting (reporting bias)	High risk	Adverse events not stated as an outcome, unclear ascertainment, no reporting of adverse events.
Other bias	Low risk	None were identified.