Irritable bowel syndrome (IBS) is a disorder that leads to pain in abdomen and changes in bowel movements.

IBS is not the same as inflammatory bowel disease (IBD).

IBS; Irritable bowel; Spastic colon; Irritable colon; Mucous colitis; Spastic colitis; Abdominal pain - IBS; Diarrhea - IBS; Constipation - IBS; IBS-C; IBS-D

The reasons why IBS develops are not clear. It can occur after a bacterial infection or a parasitic infection (such as giardiasis) of the intestines. This is called postinfectious IBS. There may also be other triggers, including stress.

The intestine is connected to the brain by hormone and nerve signals that go back and forth between the bowel and the brain. These signals affect bowel function and symptoms. The nerves can become more active during stress. This can cause the intestines to be more sensitive and contract more.

IBS can occur at any age. Often, it begins in the teen years or early adulthood. It is twice as common in women as in men.

It is less likely to begin in people above 50 years of age.

About 10% to 15% of people in the United States have symptoms of IBS. It is the most common intestinal problem that causes people to be referred to a bowel specialist (gastroenterologist).

IBS symptoms vary from person to person, and range from mild to severe. Most people have mild symptoms. You are said to have IBS when symptoms are present for at least 3 days a month for a period of 3 months or more.

The main symptoms include:

• Abdominal pain and cramps
• Gas
• Fullness
• Bloating
• Change in bowel habits. You can have either diarrhea (IBS-D), or constipation (IBS-C).

Pain and other symptoms will often be reduced or go away after a bowel movement. The pain should not occur when you are sleeping, and should not wake you up from sleep. Symptoms may flare up when there is a change in the frequency of your bowel movements.

People with IBS may go back and forth between having constipation and diarrhea or have or mostly have one or the other. This is called mixed irritable bowel syndrome, or IBS-M.

• If you have IBS with diarrhea, you will have frequent, loose, watery stools. You may have an urgent need to have a bowel movement, which may be hard to control.
• If you have IBS with constipation, you will have a hard time passing stool, as well as fewer bowel movements. You may need to strain with a bowel movement and have cramps. Often, only a small amount or no stool at all will pass.

The symptoms may get worse for a few weeks or a month, and then decrease for a while. In other cases, symptoms are present most of the time.

You may also lose your appetite if you have IBS. However, blood in stools and unintentional weight loss are not a part of IBS. If you have these symptoms, you should work with your health care provider to find out why.

The goal of treatment is to relieve symptoms.

In some people with IBS, lifestyle changes can help. For example, regular exercise and improved sleep habits may reduce anxiety and help relieve bowel symptoms.

Dietary changes can be helpful. However, no specific diet can be recommended for IBS because the condition differs from one person to another.

The following changes may help:

• Avoiding foods and drinks that stimulate the intestines (such as caffeine-containing drinks, tea, or colas)
• Eating smaller meals
• Increasing fiber in the diet (this may improve constipation or diarrhea, but make bloating worse)

Talk with your provider before taking over-the-counter medicines.

No one medicine works for everyone. Some that your provider may suggest include:

• Anticholinergic medicines (dicyclomine, propantheline, belladonna, and hyoscyamine) taken about a half-hour before eating to control intestinal muscle spasms
• Loperamide to treat IBS-D
• Alosetron (Lotronex) for IBS-D
• Eluxadoline (Viberzi) for IBS-D
• Probiotics
• Low doses of tricyclic antidepressants to help relieve intestinal pain
• Lubiprostone (Amitiza) for IBS-C
• Bisacodyl to treat IBS-C
• Rifaximin (Xifaxan), an antibiotic
• Linaclotide (Linzess) for IBS-C
• Plecanatide (Trulance) for IBS-C

Psychological therapy or medicines for anxiety or depression may help with the problem.

IBS may be a life-long condition. For some people, symptoms are disabling and interfere with work, travel, and social activities.

Symptoms often get better with treatment.

IBS does not cause permanent harm to the intestines. Also, it does not lead to a serious disease, such as cancer.

Contact your provider if you have symptoms of IBS or if you notice changes in your bowel habits that do not go away.

Published Date: April 21, 2025
Published By: Todd Eisner, MD, Private practice specializing in Gastroenterology in Boca Raton and Delray Beach, Florida at Gastroenterology Consultants of Boca Raton. Affiliate Assistant Professor, Florida Atlantic University School of Medicine. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Aronson JK. Laxatives. In: Aronson JK, ed. Meyler's Side Effects of Drugs. 16th ed. Waltham, MA: Elsevier; 2016:488-494.

Chang L. Irritable bowel and functional upper gastrointestinal syndromes. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 123.

Ford AC, Talley NJ. Irritable bowel syndrome. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 122.

Waller DG. Constipation, diarrhoea and irritable bowel syndrome. In: Waller DG, ed. Medical Pharmacology and Therapeutics. 6th ed. Philadelphia, PA: Elsevier; 2022:chap 35.