Laxatives are generally well tolerated and may be considered safe drugs. When taken at much higher than the recommended doses (laxative abuse) some side effects may occur (e.g. hypokalemia, metabolic alkalosis, renal tubular damage). It is controversial whether the laxatives currently used may lead to morphologic changes of the autonomous nervous system of the colon. Melanosis coli is due to pigment-laden macrophages within the submucosa. It occurs after long-term intake of anthraquinones and has no functional consequences. No case of ‘cathartic colon’ has been observed during the last few decades, and we can assume that it was probably caused by laxatives which are no longer in use.