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. If you have IBS with diarrhea, you likely will be tested for gluten intolerance (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.
- Manning criteria. These criteria focus on pain relieved by passing stool and on having incomplete bowel movements, mucus in the stool and changes in stool consistency. The more symptoms you have, the greater the likelihood of IBS.
- 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
- Nausea or recurrent vomiting
- Abdominal pain, especially if it's not completely relieved by 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.
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.
Imaging tests can include:
- Flexible sigmoidoscopy. Your doctor examines the lower part of the colon (sigmoid) with a flexible, lighted tube (sigmoidoscope).
- 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.
Laboratory tests can include:
- Lactose intolerance tests. Lactase is an enzyme you need to digest the sugar found in dairy products. If you don't produce lactose, you may have problems similar to those caused by IBS, including abdominal pain, gas and diarrhea. Your doctor may order a breath test or ask you to remove milk and milk products from your diet for several weeks.
- Breath test for bacterial overgrowth. A breath test also can determine if you have bacterial overgrowth in your small intestine. Bacterial overgrowth is more common among people who have had bowel surgery or who have diabetes or some other disease that slows down digestion.
- 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.
- Stool tests. Your stool might be examined for bacteria or parasites, or a digestive liquid produced in your liver (bile acid), if you have chronic diarrhea.
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, caffeine, raw fruit, and certain vegetables, such as cabbage, broccoli and cauliflower.
- 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 oligo-, di-, and monosaccharides and polyols. FODMAPs are found in certain grains, vegetables, fruits and dairy products. Your IBS symptoms might ease if you follow a strict low-FODMAP diet and then reintroduce foods one at a time.
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 symptoms, your doctor may prescribe magnesium hydroxide oral (Phillips' Milk of Magnesia) or polyethylene glycol (Miralax).
- Anti-diarrheal medications. Over-the-counter medications, such as loperamide (Imodium), 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 (Norpramine) 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're depressed and have pain and constipation.
- Pain medications. Pregabalin (Lyrica) or gabapentin (Neurontin) might ease severe pain or bloating.
Medications specifically for IBS
Medications approved for certain people with IBS include:
- Alosetron (Lotronex). Alosetron is designed to relax the colon and slow the movement of waste through the lower bowel. Alosetron can be prescribed only by doctors enrolled in a special program, is intended for severe cases of diarrhea-predominant IBS in women who haven't responded to other treatments, and isn't approved for use by men. It has been linked to rare but important side effects, so it should only be considered when other treatments aren't successful.
- Eluxadoline (Viberzi). Eluxadoline can ease diarrhea by reducing muscle contractions and fluid secretion in the intestine, and increasing muscle tone in the rectum. Side effects can include nausea, abdominal pain and mild constipation. Eluxadoline has also been associated with pancreatitis, which can be serious and more common in certain individuals.
- Rifaximin (Xifaxan). This antibiotic can decrease bacterial overgrowth and diarrhea.
- Lubiprostone (Amitiza). Lubiprostone can increase fluid secretion in your small intestine to help with the passage of stool. It's approved for women who have IBS with constipation, and is generally prescribed only for women with severe symptoms that haven't responded to other treatments.
- Linaclotide (Linzess). Linaclotide also can increase fluid secretion in your small intestine to help you pass stool. Linaclotide can cause diarrhea, but taking the medication 30 to 60 minutes before eating might help.
Potential future treatments
Researchers are investigating new treatments for IBS. Serum-derived bovine immunoglobulin/protein isolate (SBI), a nutritional therapy, has shown some promise as a treatment for IBS with diarrhea.
Studies also show that, in people who have IBS with diarrhea, a specially coated tablet that slowly releases peppermint oil in the small intestine (enteric-coated peppermint oil) eases bloating, urgency, abdominal pain and pain while passing stool. It isn't clear how enteric-coated peppermint oil might affect IBS, so ask your doctor before using it.
Lifestyle and home remedies
Simple changes in your diet and lifestyle often provide relief from IBS. Your body will need time to respond to these changes. Try to:
- Experiment with fiber. Fiber helps reduce constipation but also can worsen gas and cramping. Try slowly increasing the amount of fiber in your diet over a period of weeks with foods such as whole grains, fruits, vegetables and beans. A fiber supplement might cause less gas and bloating than fiber-rich foods.
- Avoid problem foods. Eliminate foods that trigger your symptoms.
- Eat at regular times. Don't skip meals, and try to eat at about the same time each day to help regulate bowel function. If you have diarrhea, you may find that eating small, frequent meals makes you feel better. But if you're constipated, eating larger amounts of high-fiber foods may help move food through your intestines.
- Exercise regularly. Exercise helps relieve depression and stress, stimulates normal contractions of your intestines, and can help you feel better about yourself. Ask your doctor about an exercise program.
The role of alternative therapies in relieving IBS symptoms is unclear. Ask your doctor before starting any of these treatments. Alternative therapies include:
- Hypnosis. A trained professional teaches you how to enter a relaxed state and then guides you in relaxing your abdominal muscles. Hypnosis may reduce abdominal pain and bloating. Several studies support the long-term effectiveness of hypnosis for IBS.
- Mindfulness training. Mindfulness is the act of being intensely aware of what you're sensing and feeling at every moment, without interpretation or judgment. Research indicates that mindfulness can ease symptoms of IBS.
- Acupuncture. Researchers have found that acupuncture may help improve symptoms for people with IBS.
- Peppermint. Peppermint is a natural antispasmodic that relaxes smooth muscles in the intestines. It might provide short-term relief of IBS symptoms, but study results have been inconsistent.
- Probiotics. Probiotics are "good" bacteria that normally live in your intestines and are found in certain foods, such as yogurt, and in dietary supplements. Recent studies suggest that certain probiotics may relieve IBS symptoms, such as abdominal pain, bloating and diarrhea.
- Stress reduction. Yoga or meditation can help relieve stress. You can take classes or practice at home using books or videos.
Preparing for your appointment
You may be referred to a doctor who specializes in the digestive system (gastroenterologist).
What you can do
- Be aware of any pre-appointment restrictions, such as restricting your diet before your appointment.
- Write down your symptoms, including any that may seem unrelated to the reason why you scheduled the appointment.
- Write down any triggers to your symptoms, such as specific foods.
- Make a list of all your medications, vitamins and supplements.
- Write down your key medical information, including other conditions.
- Write down key personal information, including any recent changes or stressors in your life.
- Write down questions to ask your doctor.
- Ask a relative or friend to accompany you, to help you remember what the doctor says.
Questions to ask your doctor
- What's the most likely cause of my symptoms?
- What tests do I need? Is there any special preparation for them?
- What treatment approach do you recommend? Are there any side effects associated with these treatments?
- Should I change my diet?
- Are there other lifestyle changes that you recommend?
- Do you recommend that I talk with a counselor?
- I have other health problems. How can I best manage these conditions together?
- If I have IBS, how long will it take for me to see improvement from the therapy you have prescribed?
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment anytime you don't understand something.
What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may leave time to go over points you want to spend more time on. You may be asked:
- What are your symptoms, and when did they begin?
- How severe are your symptoms? Are they continuous or occasional?
- Does anything seem to trigger your symptoms, such as foods, stress or — in women — your menstrual period?
- Have you lost weight without trying?
- Have you had fever, vomiting or blood in your stools?
- Have you recently experienced significant stress, emotional difficulty or loss?
- What is your typical daily diet?
- Have you ever been diagnosed with a food allergy or with lactose intolerance?
- Do you have any family history of bowel disorders or colon cancer?
- How much would you say your symptoms are affecting your quality of life, including your personal relationships and your ability to function at school or work?
What you can do in the meantime
While you wait for your appointment:
- Ask family members if any relatives have been diagnosed with inflammatory bowel disease or colon cancer.
- Start noting how often your symptoms occur and any factors that seem to trigger them.