Fischer 1985.

Study characteristics
Methods	Allocation: randomised, but no further information Design: parallel‐group
Participants	Number: 83 randomised Age: 18 to 65 Gender: 43 F, 30 M Setting: Netherlands Eligibility criteria: episodic vertigo for at least 1 month prior to the beginning of the study and during this period for at least 2 episodes of dizzinessExclusion criteria: middle ear infections, cervical vertigo, head injury, cerebrovascular disease, epilepsy, Parkinson's, MS, pregnancy, patients on antihistamines, phenothiazines, vasodilators, barbiturates, tranquillisers Baseline characteristics: baseline disease duration longer in betahistine group
Interventions	Betahistine 16 mg 3 times a day versus placebo for 3 months Intervention group: n = 36 Comparator group: n = 37 Use of additional interventions: none
Outcomes	Primary outcome: vertigo intensity (4‐point ordinal scale), frequency and duration of attacks Secondary outcomes: patient and physician global assessment
Funding sources	One co‐author affiliated to manufacturer; statistical advice obtained from manufacturer
Declarations of interest	As for funding sources
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Randomised"; no further information
Allocation concealment (selection bias)	Unclear risk	Method not stated
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind, but no further information
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Double‐blind, but no further information
Incomplete outcome data (attrition bias) All outcomes	High risk	10 lost after randomisation and not included in analysis
Selective reporting (reporting bias)	Low risk	Appropriate outcomes reported
Other bias	Unclear risk	—