With these blood tests, proper treatment can begin much sooner.

If you’re unlucky enough to get hit by a day or two of diarrhea, you can write it off as a short-lived bit of unpleasantness. But for those with irritable bowel syndrome (IBS), diarrhea—as well as constipation and/or other digestive problems—can be a way of life.

Imagine that you are afraid to leave the house because you might get caught without a bathroom. You suffer from gut-wrenching abdominal pain…daily bloating…and/or frequent (and unpredictable) bouts of diarrhea or constipation—or both. That is what it’s like to live with IBS.


IBS is the most common gastrointestinal problem in the US. Studies estimate that 10% to 15% of adults—as many as 37 million Americans—are affected to some degree. But without a definitive test, the approaches to diagnosis and treatment have been scattershot.

Problem: The same symptoms that occur with IBS can also be caused by other, more serious conditions (such as inflammatory bowel disease, ulcerative colitis and diverticulitis). As a result, IBS patients often undergo a multitude of tests (including stool analyses, blood tests and imaging tests) as well as doctor visits to rule out what’s not causing their problems.

Because IBS has traditionally been so difficult to diagnose, many doctors have not fully understood the disorder and blamed their patient’s IBS symptoms on stress, anxiety and/or depression…or told them that their symptoms are “all in your head” and recommended psychological counseling.

Now that’s all about to change.

Latest development: Rather than spending months—or even years—going from doctor to doctor seeking help for this condition, new blood tests allow IBS patients to learn within a matter of days what’s causing their symptoms so they can begin treatment much sooner.


The underlying cause of IBS was not known until pioneering research at Cedars-Sinai Medical Center in Los Angeles recently found that the majority of IBS patients were at some point infected with Salmonella, Escherichia coli or other harmful (and often food-borne) bacteria.

The bacteria secrete toxins that damage the intestinal nerves that control motility, the synchronized contractions that move digested food through the intestine. The nerve damage, which persists long after the infection is gone (and perhaps indefinitely), explains all of the typical IBS symptoms.

The blood tests that researchers have developed identify evidence of past infections that can cause IBS. This means that patients can describe their symptoms to a doctor, receive the new blood tests and get an accurate diagnosis after a single visit to a doctor.

Doctors send the patient’s blood samples to a laboratory (Commonwealth Laboratories, IBSchek.com) to be analyzed. The results are generally available within 24 hours. Typical cost: $500, which is usually covered by insurance.


If you get a diagnosis of IBS, what you eat can affect how well you manage your symptoms. (If you simply suspect that you have IBS but have not been diagnosed with it, it’s also worth trying the dietary changes below.) What helps…

• Avoid “FODMAP” foods. Scientists have identified a class of hard-to-digest carbohydrates that ferment in the small intestine and increase IBS symptoms. These so-called FODMAP (shorthand for fermentable oligosaccharides, disaccharides, monosaccharides and polyols) foods include wheat, dairy, onions, apples, high-fructose corn syrup, beans, stone fruits (such as apricots, nectarines and cherries) and artificial sweeteners (such as sorbitol and mannitol).

There’s some evidence that people who feel better when they give up gluten are actually responding to the reduction in FODMAPs that occurs when they go on a gluten-free diet. No one loves restrictive diets—and a low-FODMAP diet is restrictive. But it can help if you stick with it. For a comprehensive list of FODMAP foods, go to IBSDiets.org.

• Get less fiber. In the past, doctors advised IBS patients to eat a lot of fiber to firm up stools and reduce diarrhea as well as constipation. We now know that too much fiber can increase bacterial overgrowth in the small intestine.

My advice: Limit your daily fiber intake to no more than 20 g to 35 g. For example, eat white bread (such as Italian) instead of whole-wheat…avoid super-high-fiber cereals (more than 8 g of fiber per serving)…and limit beans, whole grains and other high-fiber foods.


While many IBS sufferers get relief from the dietary changes described above, medication is usually also necessary. Until recently, there were only two drugs specifically approved for IBS—alosetron (Lotronex) for diarrhea-predominant IBS, or IBS-D…and lubiprostone (Amitiza) for constipation-predominant IBS, or IBS-C. New options: In May, the FDA approved two new drugs, which may benefit a greater number of IBS patients…

Rifaximin (Xifaxan). This drug is an antibiotic, but it isn’t used to treat the infections that cause IBS (those infections are usually long gone by the time patients develop symptoms). Instead, it curtails the bacterial overgrowth in the small intestine that results from months or years of impaired motility that typically accompanies IBS symptoms. Rifaximin is taken orally three times a day, for 14 days. It is expected to become the first-line therapy for IBS-D, since it has far fewer side effects than Lotronex.

• Eluxadoline (Viberzi). This medication is an antidiarrheal. It targets opioid receptors in the intestine, while having little effect on similar receptors in the brain. This means that it’s less likely to cause drowsiness or other side effects than other medications used to treat diarrhea. It improves stool consistency and reduces abdominal pain/cramping.