Study	Reason for exclusion
Crielaard 1986	Not RCT
Dettoni 1982	Not RCT
He 2006	Not rubefacient, not blinded
Heindl 1977	Not RCT
Higashi 2010	Too short duration (12 hours)
Howell 1955	Not randomised
Jolley 1972	Oral condition
Kantor 1990	Too short duration
Kleinschmidt 1975	Quasi‐randomised
Pasila 1980	Not stated to be double‐blind. Short report, ?abstract
Shamszad 1986	Study I is a re‐published version of Golden 1978 but no data could be extracted for either Study I or Study II
von Batky 1971	Not RCT
Weisinger 1970	Oral condition, not RCT