Adverse reactions to frusemide in hospital inpatients.

Out of 2580 medical inpatients included in a drug-surveillance programme, 585 (22.7%) were treated with frusemide. Of these, 123 (21.0%) had a total of 177 adverse reactions. The most common were hypovolaemia (85 cases), hyperuricaemia (54), and hypokalaemia (21). Most reactions were mild, and only three patients had potentially life-threatening effects. The incidence of adverse reactions increased significantly with daily dose, occurring in 47 patients (13.5%) given up to 40 mg, 42 (26.3%) given up to 80 mg, and 34 (43.6%) given over 80 mg (P less than 0.001). There was no clear association between side effects and a raised blood urea concentration on admission, confirming that treatment with frusemide is not more hazardous in patients with renal failure. Frusemide is a safe and highly effective diuretic. Nevertheless, in view of the potential seriousness of volume depletion, dosage should probably begin at 20 rather than 40 mg daily.