Study	Reason for exclusion
Andrade 1983	Study period too short (6 days) and randomisation method not adequate.
Anon 2009	Commentary. Not an RCT.
Bacharier 2015	Participants not affected by asthma.
Baigelman 2015	Participants not affected by asthma.
Ball 1990	Study period too short (2 weeks).
Cogo 1994	Study of inadequate duration.
D'Azevedo Silveira 2016	Participants not affected by asthma.
Ebling 1984	Basic science study.
Feldman 1997	Basic science in vitro study.
Gong 2016	Missing a control group without macrolides. Classification of the participants unclear.
Gotfried 2004	Study was suspended because the slow enrolment of participants. The clarithromycin and placebo groups were unequal in size, and the final analysis was performed only within the treatment group, analysing data before and after the macrolide therapy within the same participants. Therefore, the study was excluded because there were no between‐study comparisons.
Hodgson 2016	Participants affected by chronic cough, not asthma.
Hueston 1991	Participants not affected by asthma.
Itkin 1970	Treatment duration < 4 weeks.
Johnston 2016	Treatment duration < 4 weeks.
Kaplan 1958	Not an RCT.
Koh 1997	Participants were children with bronchiectasis; 7 children had asthma and insufficient data were reported for these children separately.
Koutsoubari 2012	Acute exacerbations in children, trial < 4 weeks.
Lee 1998	Study on the pharmacokinetics of theophylline during macrolides administration.
Mandhane 2017	Treatment duration < 4 weeks.
Oldach 2015	Target condition not asthma.
Ram 2016	Target condition not asthma. Intervention not a macrolide.
Spector 1974	Not an RCT.
Stokholm 2016	Treatment duration < 4 weeks.
Szefler 1980	Not an RCT.
Szefler 1982a	Not an RCT.
Szefler 1982b	Not an RCT.
Takamura 2001	Not an RCT.
Wald 1986	Not an RCT.
Weinberger 1977	Not an RCT.
Zeiger 1980	Not an RCT.

RCT: randomised controlled trial.