Lack of objective evidence of efficacy of laxatives in chronic constipation.

Laxatives are commonly used to treat constipation and can be bought over-the-counter in many countries, although some preparations need to be prescribed by physicians. A meta-analysis was conducted to quantitatively evaluate the published evidence on the efficacy of laxatives in constipation. We found that large, well-controlled, published studies whose data were comparable were lacking. Of 250 articles, 35 met the inclusion criteria but only 11 yielded usable data (N = 375 patients on laxatives, 174 on placebo). There was an effect of laxatives on stool frequency (mean increase 1.9 stools per week) and stool weight (mean increase 476 g) but this was not clearly distinguishable from that of placebo therapies (1 stool and 434 g, respectively) in studies up to 4 weeks in duration. Similarly, studies of 5-12 weeks yielded no differences overall. These results cannot definitively rule out laxatives as an effective treatment, due to the poor published evidence. Better evidence is required to justify the continued expenditure of funds on laxatives by both patients and formularies.