Laxatives are medications that promote bowel movements in patients who suffer from constipation. They are typically used only after changes in diet, exercise and other lifestyle patterns fail to promote regularity.

Physicians may also instruct patients to take laxatives prior to certain medical procedures, such as a colonoscopy, which helps detect the presence of colon cancer.

Bowel movements occur with varying frequency among healthy people. However, factors such as a poor diet, physical inactivity, pregnancy, illness and stress can all interrupt a patient’s ability to have normal bowel movements. Laxatives can promote bowel movements in different ways. Some medications soften stools whereas others trigger rhythmic muscle contractions in the intestines that encourage bowel movements to occur.

There are several different types of laxatives. They include:

• Bulking agents. Add water to stool to increase its bulk and stimulate the natural contractions of the large intestine.
  

  

• Stimulant laxatives. Contain stimulants, such as senna, cascara and bisacodyl, which trigger rhythmic muscle contractions in the intestines.
  
  
• Osmotic agents. Draw water from surrounding tissues into the bowel, which creates a soft stool mass and stretches the walls of the large intestine, thereby stimulating contractions.
  
  
• Stool softeners. Add moisture to the stool and prevent dehydration, which keeps the stool from becoming hard and dry.

Most laxatives are available in over-the-counter formulations. They are delivered either orally or rectally. Some are intended to gradually promote regularity over a period of time whereas others work quickly to trigger bowel movements within hours or even minutes.

Although laxatives can help people restore their bowel movements, these medications can also pose certain risks. Frequent use of laxatives can aggravate or even cause constipation. Patients who use certain laxatives too often may develop lazy bowel syndrome, in which the bowels fail to properly function without the aid of laxatives. Pregnant and breastfeeding women, children and elderly people should use extra caution when taking laxatives, as they may have negative effects. For these reasons, patients should not take laxatives without first consulting their physician.