Gokhale 1996.

Methods	RCT
Participants	Included: 556 girls aged 12 to 21 years, with moderate to very severe spasmodic dysmenorrhoea Location: India
Interventions	Group 1: thiamine hydrochloride (vitamin B1) 100 mg orally daily for 90 days Group 2: placebo
Outcomes	Cured: complete disappearance of pain; pain relief; side effects.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"using random tables...a randomised, double‐blind, placebo‐controlled study was carried out on 556 girls aged 12‐21 yr".
Allocation concealment (selection bias)	Unclear risk	"a randomised, double‐blind, placebo‐controlled study was carried out on 556 girls aged 12‐21 yr".
Blinding (performance bias and detection bias) All outcomes	Low risk	Comment: participants and observers were blinded, and the placebo was identical.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: final outcomes were unobtainable for 24 girls, and the dropout rate was 4.3% (24/556).
Selective reporting (reporting bias)	Unclear risk	Comment: there were no comparative data on adverse events.
Other bias	Low risk	Comment: we did not identify any other potential sources of bias.