Purgative abuse This is most commonly seen in females who surreptitiously take high-dose purgatives and are often extensively investi- gated for chronic diarrhoea. The diarrhoea is usually of high volume (> 1 L daily) and patients may have a low serum potassium. Biochemical analysis of the stool may help diag- nose laxative abuse. Management is difficult as most patients deny purgative ingestion. Purgative abuse often occurs in association with eating disorders and patients may need psychiatric help.