Ginsberg 1987.

Methods	RCT, DB, parallel groups Duration 14 days Assessment on days 3, 14
Participants	Acute mechanical low back pain N = 40
Interventions	Methylsalicylate (2.6%), ethylsalicylate (1.8%), glycol salicylate (0.9%), salicylic acid (0.9%), camphor (0.4%), menthol (5.5%), capsicum oleoresin (1.5%) ointment (Rado‐Salil), n = 20 Placebo ointment, n = 20 Frequency of application not stated
Outcomes	PI: 100 mm VAS Duration of confinement to bed Muscular reflex contracture 5‐point scale Spine mobility: Schober's index Finger‐floor distance Lumbar extension Patient global assessment: 5‐point scale Use of rescue medication (paracetamol 250 mg tablets) Amount of ointment used Adverse events
Notes	Oxford Quality Score: R1, DB2, W0. Total = 3/5 No analgesics, anti‐inflammatories, or physical treatments allowed other than rescue medication (max 45 x 250 mg paracetamol)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method used to generate random sequence not described
Allocation concealment (selection bias)	Unclear risk	Method not described
Blinding (performance bias and detection bias) All outcomes	Low risk	"Placebo was identical in appearance"
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants accounted for
Size	High risk	< 50 participants per treatment arm