irritable bowel syndrome

There's no test to definitively diagnose IBS. Your doctor is likely to start with a complete medical history, physical exam and tests to rule out other conditions, such as celiac disease.

After other conditions have been ruled out, your doctor is likely to use one of these sets of diagnostic criteria for IBS:

Rome criteria. These criteria include abdominal pain and discomfort lasting on average at least one day a week in the last three months, associated with at least two of these factors: Pain and discomfort are related to defecation, the frequency of defecation is altered, or stool consistency is altered.

Type of IBS. For the purpose of treatment, IBS can be divided into three types, based on your symptoms: constipation-predominant, diarrhea-predominant or mixed.

Your doctor will also likely assess whether you have other signs or symptoms that might suggest another, more serious, condition. These signs and symptoms include:

Onset of signs and symptoms after age 50

Weight loss

Rectal bleeding

Fever

Nausea or recurrent vomiting

Abdominal pain, especially if it's not related to a bowel movement, or occurs at night

Diarrhea that is persistent or awakens you from sleep

Anemia related to low iron

If you have these signs or symptoms, or if an initial treatment for IBS doesn't work, you'll likely need additional tests.

Additional tests

Your doctor may recommend several tests, including stool studies to check for infection or problems with your intestine's ability to take in the nutrients from food (malabsorption). You may also have a number of other tests to rule out other causes for your symptoms.

Diagnostic procedures can include:

Colonoscopy. Your doctor uses a small, flexible tube to examine the entire length of the colon.

X-ray or CT scan. These tests produce images of your abdomen and pelvis that might allow your doctor to rule out other causes of your symptoms, especially if you have abdominal pain. Your doctor might fill your large intestine with a liquid (barium) to make any problems more visible on X-ray. This barium test is sometimes called a lower GI series.

Upper endoscopy. A long, flexible tube is inserted down your throat and into the tube connecting your mouth and stomach (esophagus). A camera on the end of the tube allows the doctor to inspect your upper digestive tract and obtain a tissue sample (biopsy) from your small intestine and fluid to look for overgrowth of bacteria. Your doctor might recommend endoscopy if celiac disease is suspected.

Treatment of IBS focuses on relieving symptoms so that you can live as normally as possible.

Mild signs and symptoms can often be controlled by managing stress and by making changes in your diet and lifestyle. Try to:

Avoid foods that trigger your symptoms

Eat high-fiber foods

Drink plenty of fluids

Exercise regularly

Get enough sleep

Your doctor might suggest that you eliminate from your diet:

High-gas foods. If you experience bloating or gas, you might avoid items such as carbonated and alcoholic beverages and certain foods that may lead to increased gas.

Gluten. Research shows that some people with IBS report improvement in diarrhea symptoms if they stop eating gluten (wheat, barley and rye) even if they don't have celiac disease.

FODMAPs. Some people are sensitive to certain carbohydrates such as fructose, fructans, lactose and others, known as FODMAPs — fermentable oligosaccharides, disaccharides, monosaccharides and polyols. FODMAPs are found in certain grains, vegetables, fruits and dairy products.

A dietitian can help you with these diet changes.

If your problems are moderate or severe, your doctor might suggest counseling — especially if you have depression or if stress tends to worsen your symptoms.

In addition, based on your symptoms your doctor might suggest medications such as:

Fiber supplements. Taking a supplement such as psyllium (Metamucil) with fluids may help control constipation.

Laxatives. If fiber doesn't help constipation, your doctor may recommend over-the-counter laxatives, such as magnesium hydroxide oral (Phillips' Milk of Magnesia) or polyethylene glycol (Miralax).

Anti-diarrheal medications. Over-the-counter medications, such as loperamide (Imodium A-D), can help control diarrhea. Your doctor might also prescribe a bile acid binder, such as cholestyramine (Prevalite), colestipol (Colestid) or colesevelam (Welchol). Bile acid binders can cause bloating.

Anticholinergic medications. Medications such as dicyclomine (Bentyl) can help relieve painful bowel spasms. They are sometimes prescribed for people who have bouts of diarrhea. These medications are generally safe but can cause constipation, dry mouth and blurred vision.

Tricyclic antidepressants. This type of medication can help relieve depression as well as inhibit the activity of neurons that control the intestines to help reduce pain. If you have diarrhea and abdominal pain without depression, your doctor may suggest a lower than normal dose of imipramine (Tofranil), desipramine (Norpramin) or nortriptyline (Pamelor). Side effects — which might be reduced if you take the medication at bedtime — can include drowsiness, blurred vision, dizziness and dry mouth.

SSRI antidepressants. Selective serotonin reuptake inhibitor (SSRI) antidepressants, such as fluoxetine (Prozac, Sarafem) or paroxetine (Paxil), may help if you are depressed and have pain and constipation.

Pain medications. Pregabalin (Lyrica) or gabapentin (Neurontin) might ease severe pain or bloating.