Study	Reason for exclusion
Belcher 1986	Study conducted on adults and induced cough in normal subjects
Davies 1999	RCT of steroids in paediatric cough
de Benedictis 1986	Not RCT therapeutic trial
Ellul‐Micallef 1983	Study conducted on adults
Irwin 1997	Study conducted on adults
Lowry 1987	Study conducted on adults and induced cough in normal subjects
Lui 1996	Study conducted on adults and induced cough
Mulrennan 2002	Study conducted in healthy adult smokers
Spelman 1991	Not RCT