Tukiainen 1986.

Methods	RCT. Withdrawals not mentioned
Participants	Finland: 108 adults with acute respiratory infection with cough (mean duration 9 days); per cent with wheezing on initial exam not mentioned
Interventions	Oral salbutamol (2 mg every 8 hours) + dextromethorphan (N=38) versus dextromethorphan only (N = 36) versus placebo (N = 34) for 4 days. Only groups 1 and 2 were used for the analyses in this review
Outcomes	Daily symptom scores for day cough frequency and severity, night cough severity, and breathlessness; and number with side effects
Notes	Prohibited other antitussives, expectorants, mucolytics, and antibiotics Study medication was provided by a pharmaceutical company and a pharmaceutical company employee was listed as an author
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The study is described as randomised, but there is no information about the sequence generation process. Also, the groups had different number of participants (38, 36, and 34) and some of the participants characteristics were not similar between groups
Allocation concealment (selection bias)	Unclear risk	The study is described as randomised, but there is no information about the method of allocation used
Blinding (performance bias and detection bias) All outcomes	Unclear risk	The methods used for blinding were not described. The group receiving beta agonists had significantly more tremor, so participants and providers may have become aware of their assignment group
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No data were provided on the number or characteristics of dropouts, or ways in which dropouts were handled
Selective reporting (reporting bias)	Low risk	Results included data on all outcomes except breathlessness

exam: examination
 FEV‐1: forced expiratory volume in 1 second
 GI: gastro intestinal
 ITT: intention‐to‐treat
 OTC: over‐the‐counter
 RCT: randomised controlled trial