Okamato 1968.

Study characteristics
Methods	Double‐blind, parallel trial Two‐week duration
Participants	36 patients with Ménière's disease (grade III, but very lax criteria)
Interventions	Betahistine 18 mg twice daily versus placebo
Outcomes	Vertigo (grade II). No difference from placebo Hearing loss (grade II). No difference from placebo Tinnitus (grade I). Reduced with betahistine
Notes	Allocation bias: low Attrition bias: medium
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Low risk	A ‐ Adequate