In most cases, you can successfully control mild symptoms of IBS by learning to manage stress and making changes in your diet and lifestyle. But if your problems are moderate or severe, you may need more help than lifestyle changes alone can offer.

For moderate IBS, your doctor may suggest taking fiber supplements such as psyllium (Metamucil) or methylcellulose (Citrucel) with fluids, to help control constipation and over-the-counter medications such as loperamide (Imodium) to help control diarrhea. In some cases, you may need drugs that affect certain activities of the nervous system (anticholinergics) to relieve painful bowel spasms. If so, follow-up with your doctor is very important.

If your symptoms include pain and depression, your doctor may recommend a tricyclic antidepressant or a selective serotonin reuptake inhibitor (SSRI). These medications help relieve depression as well as inhibit the activity of neurons that control the intestines. For diarrhea and abdominal pain, your doctor may suggest tricyclic antidepressants such as imipramine (Tofranil) and amitriptyline (Elavil). Side effects of these drugs include drowsiness and constipation.

Selective serotonin reuptake inhibitors such as fluoxetine (Prozac, Sarafem) or paroxetine (Paxil) may be helpful if you're depressed and have pain and constipation. If these medications don't work, you may have better results from counseling. If you have severe IBS, it's important to receive ongoing treatment and support from your physician.

In November 2000, the Food and Drug Administration (FDA) approved the first medication specifically for the treatment of moderate to severe symptoms of IBS in women. Alosetron (Lotronex) is a nerve receptor antagonist that's supposed to relax the colon and slow the movement of waste through the lower bowel. But the drug was pulled from the market just nine months after its approval when it was linked to at least four deaths and severe side effects in 197 people.

In June 2002, the FDA took the unprecedented step of allowing Lotronex to be sold again — with a number of restrictions. The drug can be prescribed only by doctors enrolled in a special program and is intended for severe cases that haven't responded to other treatments. Lotronex is not approved for use by men or for women who don't have the diarrhea-predominant form of IBS.

For women who have IBS with constipation, the FDA approved the medication tegaserod (Zelnorm) in July 2002. It's approved only for short-term use in women, and has not been approved for use in men. Tegaserod imitates the action of the neurotransmitter serotonin and helps to coordinate the nerves and muscles in the intestine.