42 outpatients with chronic diarrhoea of varying origin received individually adapted doses (2–12 mg) of loperamide for a median time of 543 days (range 140–1,159 days). In most cases, the mean daily stool frequency dropped significantly and stool consistency improved clearly; the beneficial effects of the drug were maintained over the entire treatment period. Also, patients with diarrhoea of organic origin tended to react more favourably to loperamide than patients with functional diarrhoea. No drug-related changes in laboratory parameters could be detected and clinical side effects were virtually nil. No morphine-like effect of loperamide could be evidenced by means of the pupil diameter changes after naloxone administrat