Laxatives for Constipation

  • Medical Author:
    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.

  • Medical Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

Constipation Myths & Facts

Quick GuideDigestive Disorders: Constipation Myths and Facts

Digestive Disorders: Constipation Myths and Facts

What over-the-counter preparations can be used for constipation?

Laxatives are medicines that increase the frequency and ease of passing stool. Many types of laxatives are available over-the-counter (OTC) for the relief of mild, occasional constipation. If constipation becomes moderate to severe or does not respond to OTC products, consult a doctor.

Most OTC laxatives are safe, effective, and well tolerated. There are distinct classes of laxatives that function differently and have varying degrees of effectiveness and potential side effects.

Bulk-forming laxatives

Bulk-forming laxatives are the most commonly recommended initial treatments for constipation. Bulk-forming laxatives may work as quickly as 12 hours or take as long as three days to be effective. Some bulk-forming laxatives are derived from natural sources such as agar, psyllium, kelp (alginates), and plant gum. Others are synthetic cellulose compounds such as methylcellulose and carboxymethylcellulose. Natural and synthetic bulk-forming laxatives act similarly. They dissolve or swell in the intestines, lubricate and soften the stool, and make the passage of stool easier and more frequent.

Examples of bulk-forming laxatives are methylcellulose (Citrucel) psyllium hydrophilic mucilloid (Metamucil), polycarbophil (FiberCon), guar gum (Benefiber) and malt soup extract (Maltsupex). Many of these agents are available as powders and are taken mixed with fluids. Fruit drinks, fruit juice, and soft drinks mask the gritty taste of these laxatives better than water. Some are available as wafers, which are designed to be eaten with a separate beverage.

The benefits of bulk-forming laxatives are:

  • Bulk-forming laxatives are not absorbed from the intestines into the body and are safe for long-term use. They are also safe for elderly patients with constipation.
  • They are helpful in patients with irritable bowel syndrome (IBS), diverticulosis, and colostomies.
  • Some bulk-forming laxatives (such as guar gum) are used as fiber supplements in patients whose diets contain insufficient fiber. High fiber consumption can help control weight gain and sometimes modestly lower the level of cholesterol in the blood.

Precautions for using bulk-forming laxatives

  • Each dose of a bulk-forming laxative should be taken with at least a full glass (8 ounces) of fluid to be safe and effective. Bulk-forming laxatives may not be appropriate for individuals who must restrict oral fluid intake (such as patients with kidney failure).
  • Individuals with narrowing of the digestive tract (including esophageal stricture, intestinal stricture, or severe adhesions from previous surgery) should not use bulk-forming agents without their doctors' approval due to the risk of blockage of the intestine or the esophagus.
  • Some individuals may be allergic to the laxative or other substances contained in the product, such as coloring or artificial sweeteners.
  • Abdominal bloating, discomfort, and flatulence (gas) can be bothersome to some people using bulk-forming laxatives. By trying different types of bulk-forming laxatives, it usually is possible to find one that does not cause discomfort.
  • Some of these products contain sugar. People with diabetes mellitus may need to select sugar-free bulk-forming laxatives.
  • Bulk-forming laxatives can decrease the absorption of certain medications such as aspirin, warfarin (Coumadin), and carbamazepine (Tegretol) and can also reduce blood sugar levels.
Medically Reviewed by a Doctor on 3/7/2016

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