The side effects of anthraquinones, diphenylmethane derivatives (e.g. bisacodyl, sodium picosulphate), saline laxatives, lactulose, and cisapride are discussed. When taken in recommended doses, no relevant side effects have been observed, except for hypermagnesemia following magnesium containing cathartics in renal insufficiency. This holds also true for the time of pregnancy and lactation. (Pseudo-)melanosis coli is characterized by pigment loaded macrophages without apparent functional consequences. It occurs mainly after anthraquinones, but to a lesser degree also after diphenylmethane derivatives. Clinically relevant side effects of the above laxatives have been published exclusively after excessive dosing. They consist in electrolyte disturbances (mainly hypokalemia), metabolic alkalosis, renal tubular dysfunction, and other less frequent side effects. Cases of "cathartic colon" have not been published during the last decades. It was probably due to laxatives which are no longer used.