Constipation affects 15-25% of people. Its mechanisms are various. There are constipations due to intestinal dyskinesia (functional constipation, irritated bowel syndrome), slow transit (colonic inertia), and muscular apparatus discoordination ensuring defecation (dyssynergic defecation). The treatment of different types of constipation uses prokinetics (type 4 serotonin receptor agonists, chlorine channels activators and guanylate cyclase C channel activators) or spasmolytics, among which pinaverium bromide (dicetel) has demonstrated its high efficacy. Biofeedback therapy or surgical techniques may be used. There is a need to prescribe laxatives in any type of constipation. A pathogenetic approach to treating constipation is most efficient. The paper characterizes stimulant, osmotic, volume, and emollient laxatives and agents stimulating the urge to defecate. It also gives the data of meta-analyses evaluating the efficacy of different drug groups. Particular emphasis is laid of the effect of lactulose and its first preparation - duphalac.