Enteric viruses including noroviruses and rotavirus are leading causes of diarrhoeal disease and gastroenteritis worldwide, and there is no effective treatment.

To evaluate nitazoxanide, a thiazolide anti-infective agent, in treating viral gastroenteritis in adults and adolescents.

50 out-patients at least 12 years of age (mean 33.5 years) presenting with diarrhoea and stool-positive by enzyme-linked immunosorbent assay for norovirus, rotavirus or adenovirus were enrolled in a double-blind, placebo-controlled clinical trial. Patients were randomly assigned either nitazoxanide 500 mg or placebo twice daily for 3 days. The primary end point was time from first dose to resolution of symptoms. Analysis was modified intent-to-treat for 45 patients, excluding five patients with other identified enteropathogens at baseline.

The median time from first dose to resolution of symptoms was 1.5 days (IQR: 0.5-2.5) for nitazoxanide-treated patients and 2.5 days (IQR: 1.5-4.5) for the placebo group. Significant reductions in time to resolution of symptoms were observed for all patients analysed (P < 0.0001) and for subsets of patients with rotavirus (P = 0.0052) and norovirus (P = 0.0295). The number of patients with adenovirus (n = 5) was too small to draw any conclusion. No significant adverse events were reported.

Nitazoxanide may play an important role in managing viral gastroenteritis in adults.