Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Headache
[78] RCT 3-armed trial	642 men aged 18 to 75 years with stable chronic congestive heart failure (all participants were already receiving diuretics and digoxin)	Proportion of people with headache 23/186 (12%) with hydralazine plus isosorbide dinitrate 1/273 (0.4%) with placebo	Significance not assessed
[79] RCT	1050 African-Americans with New York Heart Association (NYHA) class III or IV heart failure with dilated ventricles	Proportion of people with headache 6 months 48% with hydralazine plus isosorbide dinitrate 19% with placebo Absolute numbers not reported	P <0.001 The RCT was terminated early (after 10 months instead of 18 months) because mortality was higher with placebo	Effect size not calculated	placebo
Dizziness
[78] RCT 3-armed trial	642 men aged 18 to 75 years with stable chronic congestive heart failure (all participants were already receiving diuretics and digoxin)	Proportion of people with dizziness 12/186 (6%) with hydralazine plus isosorbide dinitrate 5/273 (2%) with placebo	Significance not assessed
[79] RCT	1050 African-Americans with NYHA class III or IV heart failure with dilated ventricles	Proportion of people with dizziness 6 months 29% with hydralazine plus isosorbide dinitrate 12% with placebo Absolute numbers not reported	P <0.001 The RCT was terminated early (after 10 months instead of 18 months) because mortality was higher with placebo	Effect size not calculated	placebo