Study	Reason for exclusion
Abelson 1989	Not topical treatment.
Carenini 1993	Not RCT.
Chen 2015	Study only performed follow‐up for 2 weeks in total.
Dehgan 1992	Not able to source paper.
Duong 2015	Not RCT.
Hendrikse 1982	Not able to source paper.
Hollwich 1983	Not relevant comparator.
ISRCTN02628492	Study was terminated due to lack of funding.
Miyake 2000	Probably not random allocation, unclear response from study author.
Nishino 2009	Not relevant intervention.
Riley 2006	Not relevant intervention.
Sanders 1982	Not able to source paper.
Sellares 1992	Not able to source paper.
Sholiton 1979	Not topical treatment.
Tang 2015	Not relevant intervention.
Wolf 2007	Not RCT.
Yamaaki 1984	Not RCT.
Yilmaz 2012	Not RCT.

RCT: randomised controlled trial