Symptoms:

Symptoms range from mild to severe. Most people have mild symptoms. Symptoms are different from person to person.

The main symptoms of IBS are abdominal pain, fullness, gas, and bloating that have been present for at least 3 days a month for the last 3 months. The pain and other symptoms will often:

• Be reduced or go away after a bowel movement
• Occur when there is a change in how often you have bowel movements

People with IBS may switch between constipation and diarrhea, or mostly have one or the other.

• People with diarrhea will have frequent, loose, watery stools. They will often have an urgent need to have a bowel movement, which may be hard to control.
• Those with constipation will have a hard time passing stool, as well as fewer bowel movements. They will often need to strain and will feel cramps with a bowel movement. Often, they do not release any stool, or only a small amount.

For some people, the symptoms may get worse for a few weeks or a month, and then decrease for a while. For other people, symptoms are present most of the time.

People with IBS may also lose their appetite.

Signs and tests:

Most of the time, your doctor can diagnose IBS based on your symptoms, with few or no tests. Eating a lactose-free diet for 2 weeks may help the doctor check for a possible lactase deficiency.

There is no test to diagnose IBS. Tests may be done to rule out other problems:

• Blood tests to see if you have celiac disease or a low blood count (anemia)
• Stool cultures to check for an infection

Some patients will have colonoscopy. During this test, a flexible tube is inserted through the anus to examine the colon. You may need this test if:

• Symptoms began later in life (over age 50)
• You have symptoms such as weight loss or bloody stools
• You have abnormal blood tests (such as a low blood count)

Other disorders that can cause similar symptoms include:

• Celiac disease
• Colon cancer (cancer rarely causes typical IBS symptoms, unless symptoms such as weight loss, blood in the stools, or abnormal blood tests are also present)
• Crohn's disease or ulcerative colitis