Most people who are mildly constipated do not need laxatives. However, for those who have made diet and lifestyle changes and are still constipated, doctors may recommend laxatives for a limited time.

A doctor should determine when you need a laxative and which form is best. Laxatives taken by mouth are available in liquid, tablet, gum, powder, and granule forms. They work in various ways:

  • Bulk-forming laxatives generally are considered the safest but can interfere with absorption of some medicines. These laxatives, also known as fiber supplements, are taken with water. They absorb water in the intestine and make the stool softer. (e.g., Metamucil, Citrucel, Konsyl, and Serutan.)
  • Osmotic laxatives are poorly absorbed compounds that cause an influx of water into the small intestine and colon, thereby increasing stool bulk. Polyethylene glycol produces less intestinal gas and causes less abdominal bloating and flatulence than other osmotic laxatives.
  • Stimulants cause rhythmic muscle contractions in the intestines. (e.g., Correctol, Dulcolax, Purge, and Senokot.) Studies suggest that phenolphthalein, an ingredient in some stimulant laxatives, might increase a person's risk for cancer. The Food and Drug Administration has proposed a ban on all over-the-counter products containing phenolphthalein. Most laxative makers have replaced or plan to replace phenolphthalein with a safer ingredient.
  • Stool softeners provide moisture to the stool and prevent dehydration. These laxatives are often recommended after childbirth or surgery. (e.g., Colace and Surfak.)
  • Lubricants grease the stool enabling it to move through the intestine more easily. Mineral oil is the most common example.
  • Saline laxatives (a type of osmotic laxative) act like a sponge to draw water into the colon for easier passage of stool. (e.g., Milk of Magnesia and Haley's M-O.)

People who are dependent on laxatives need to slowly stop using them. A doctor can assist in this process. In most people, this restores the colon's natural ability to contract.

Adapted from NIH Publication No. 03-2754, June 2003; the text of this article is not copyrighted.

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