Q. My doctor says I have irritable bowel syndrome. What is this, and what can I do?

A. This is defined as abdominal discomfort or pain over at least 12 weeks (which need not be consecutive) in the past 12 months that includes two of the following: relief by defecation, a change in frequency of stool, or a change in form (appearance) of stool (such as constipation, diarrhea or both). There may be straining, urgency, bloating or a feeling of incomplete evacuation.

Affecting 10 to 15 percent of the population, IBS is twice as common in women. Red flags such as weight loss, blood in stools, age 50 and older, family history of colon cancer or of inflammatory bowel disease, fever or anemia merit an early doctor visit. There is no cure for IBS, but the condition does not lead to cancer or any other serious ailment. Its cause is unknown.

If you are experiencing IBS symptoms, you should avoid alcohol and caffeine and, if you smoke, quit smoking. You need regular sleep and exercise. You should not have any dairy products for three weeks to see if lactose is causing the discomfort. Seek counseling to treat any stress- or anxiety-related component.

A recent review of 17 studies found that fiber does not relieve IBS pain. Still, it may help some folks, and soluble fiber causes less gas and bloating than insoluble fiber, so try eating more fruits, oats and barley for a few weeks, and if this doesn't help, then try commercial supplements such as calcium polycarbophil or methylcellulose. Similarly, the evidence is weak that laxatives work, but those with constipation may find products such as Miralax and Glycolax worth trying.

The Cochrane Database group looked at only the most accurate studies and found the evidence for the effectiveness of tricyclic antidepressants and antispasmodic drugs to be weak. Although antispasmodics as a class consistently reduced abdominal pain, it is unclear whether individual antispasmodic drugs such as dicyclomine (Bentyl) do.

Tegaserod is a serotonin drug that helps women with constipation-predominant IBS, although its benefits are modest — you'd have to treat 14 women to improve symptoms in one. It is approved only for 4 to 6 weeks, and those who respond can continue it another 4 to 6 weeks. After this, some doctors use it intermittently or at a lower dose. Two recent small studies found that the serotonin antidepressants fluoxetine and citalopram reduced IBS pain.

Finally, the Cochrane group found that some herbs may be a promising IBS treatment. However, the quality of most studies was poor, and there were safety and efficacy concerns. Testing of the herbs in larger, welldesigned trials was called for.

For more dietary advice, see Amy Tousman's Prescriptions column on irritable bowel syndrome, published Feb 9.

Dr. Landis Lum is a family-practice physician for Kaiser Permanente and an associate clinical professor at the University of Hawai'i's medical school. Send questions to Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; islandlife@honoluluadvertiser .com or fax 535-8170. This column is not intended to provide medical advice.