Anticholinergics (antispasmodics) for irritable bowel syndrome


Generic Name Brand Name
dicyclomine hydrochloride Bentyl
hyoscyamine sulfate Anaspaz, Cystospaz-M, Levsin

How It Works

Antispasmodics relax the smooth muscles of the gut, helping to prevent or relieve painful cramping spasms in the intestines. These medications can be taken as needed for cramps. They can also be taken 30 to 45 minutes before meals that you expect might cause symptoms or when symptoms would be inconvenient or bothersome.

Why It Is Used

Antispasmodics are used to relieve cramps or spasms of the stomach, intestines, or bladder. They are the most commonly prescribed medications for treating irritable bowel syndrome (IBS).1

IBS is a disorder of the intestines that causes abdominal pain or discomfort with constipation or diarrhea (and sometimes alternating episodes of both). Other common symptoms include bloating and passing mucus in the stools. The condition is more common in women than in men.

Do not use antispasmodics if you suffer from:

How Well It Works

Some studies suggest that antispasmodics improve symptoms of IBS and reduce pain.2 But studies on antispasmodics available in the United States have been less promising. Some studies show a benefit and some don't.3

Side Effects

Side effects may include drowsiness, dry mouth, blurred vision, or an inability to urinate. Antispasmodics may make constipation—often a main symptom of IBS—worse.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

If constipation is your main symptom, antispasmodics may not work for you. In some cases, use of antispasmodics can make constipation worse.

If you are pregnant, ask your doctor about taking antispasmodics. Some studies have suggested that some antispasmodics can increase the heartbeat of a fetus, and that some are related to birth defects, though they have not been proven to cause these defects.

If you suffer from glaucoma or urinary retention, do not use antispasmodics.

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  1. Hasler WL (2002). The irritable bowel syndrome. Medical Clinics of North America, 86: 1525–1551.
  2. Mertz HR (2003). Irritable bowel syndrome. New England Journal of Medicine, 349(22): 2136–2146.
  3. Brandt LJ, et al. (2002). Systematic review on the management of irritable bowel syndrome in North America. American Journal of Gastroenterology, 97(11, Suppl): S7–S26.

Last Updated: May 23, 2008

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