Home>>Family Medicine>>Adult Health: Constipation: Laxatives


What are laxatives?
Laxatives are drugs used to treat constipation. Having constipation means that you have a bowel movement fewer than 3 times a week. The bowel movements are usually hard, dry, and small. Constipation is more common in women and older adults. Laxatives help you have more bowel movements or make passing a bowel movement more comfortable.

When are they used?
You may have constipation because you:

  • Wait too long to have bowel movements.
  • Do not drink enough fluids.
  • Do not eat enough fiber.
  • Eat too many foods that cause constipation, such as cheese.
  • Do not have enough physical activity.
  • Use laxatives too often.
  • Are taking a medicine that has a side effect of constipation.
  • Have a medical condition or illness that causes constipation.

How do they work?
There are many types of laxatives. Each type works a little differently.

  • Bulk-forming products such as Metamucil or other psyllium fiber products make the stool larger. The increase in size helps the stool to move. This kind of laxative should be taken with at least 1 full glass of water or juice. Be sure to take bulk-forming laxatives at least 2 hours before or after other oral medicines. Many people find fiber supplements to be helpful, but in a few cases they make constipation worse.
  • Stimulant laxatives such as Dulcolax or other products that contain bisacodyl, castor oil, or casanthranol, make the intestines contract to push the bowel movement through.
  • Lubricant laxatives such as mineral oil soften the stool. This makes it easier to pass.
  • Saline laxatives such as Fleet Phospho-soda or other products that contain magnesium citrate increase the salt content in the stool. The increased salt pulls body fluids into the stools, making them softer and easier to pass out of the body.
  • Hyperosmotic laxatives such as milk of magnesia pull water into the bowel and the stool. This makes the stool more liquid, softer, and easier to pass. This type of laxative also helps the bowel move the stool forward.
  • Stool-softener laxatives such as docusate (Colace) help keep the stool soft and easier to pass. These laxatives also increase the amount of water in the stool, but they have no effect on how the bowel muscles act.

Bulk-forming products such as Metamucil or other psyllium fiber products are the only type of laxative that can be taken long term. The other types are not recommended for long-term use.

What should I watch out for when taking laxatives?
Laxatives are usually for short-term use, meaning less than 1 week. Bulk-forming products can be used long-term and may be needed by many older adults. If constipation continues for 2 weeks, tell your health care provider. Some diseases can cause a change in bowel habits.

Do not use laxatives too much. Using too many laxatives or using them too much can have serious effects:

  • It can damage the muscular function of the bowel.
  • You may need more and more of the laxative to get results, until eventually the laxative does not work.
  • Excessive laxative use can drain the body of water, vitamins, and minerals.
  • It can cause kidney stones or kidney failure.
  • The effects of other medicines can be changed.

How can I take care of myself?
To help take care of yourself:

  • Eat fresh vegetables and fruit every day.
  • Exercise regularly according to your health care provider's recommendations. For example, walk for at least 20 minutes every day.
  • Drink prune juice or eat stewed fruits at breakfast.
  • Drink plenty of fluids.
  • Increase the whole-grain fiber in your diet by eating cereals with 5 or more grams of fiber per bowl (for example, shredded wheat or bran flakes).
  • Take a fiber product such as Metamucil or Citrucel if you are constipated. Follow directions on the product label. If the problem continues, tell your health care provider.
  • Do not use too many laxatives.