For many people with irritable bowel syndrome (IBS), "irritable" doesn't even begin to describe the uncomfortable, embarrassing, and inconvenient ways in which this condition compromises their lives. Sometimes IBS is just mildly annoying; at other times, it's disabling. Some people with IBS are afraid to leave their homes because they're ashamed of their symptoms, or they don't want to be very far from a bathroom. Irritable bowel syndrome affects 10% to 22% of adults, the majority of them women. The good news for women with IBS is that the FDA has recently approved a new drug specifically for treatment of IBS symptoms in women. In addition, researchers are gaining a better understanding of what may cause IBS, which should result in more treatment options.
WHAT IS IBS?
IBS causes recurrent episodes of constipation, diarrhea, or alternating bouts of each, often accompanied by abdominal cramps and bloating. Some people with IBS pass mucus in their stool; others feel their bowels are still full, even right after a bowel movement. Irritable bowel syndrome is a functional disorder. This means the function of the colon (large intestine) is impaired, but there is no sign of disease upon examination of the colon, nor any structural or biochemical abnormalities to explain the symptoms. While IBS is uncomfortable and distressing, it does not cause intestinal bleeding or cancer. IBS shouldn't be confused with inflammatory bowel diseases such as ulcerative colitis or Crohn's disease, more serious conditions involving inflammation, infection and/or tissue damage.
For years, people believed IBS was caused purely by emotion or stress. Scientists now see it as a condition with both psychological and physiological components. The gastrointestinal tract as a whole, and digestion in particular, is influenced by neural connections between the brain and the gut. As a result, emotion or thought can affect muscle contractions of the intestine. Contractions of the large intestine, or colon, also are controlled by a combination of nerves, hormones, and electrical activity in the colon muscle itself. Research suggests that colon muscles of people with IBS contract erratically, resulting in constipation, diarrhea, or both.
To make matters worse, people with IBS are more sensitive to gastrointestinal stimuli than people without the condition. Nerve endings in the lining of their colons are unusually sensitive. In one study, researchers slowly filled deflated latex balloons placed in the empty rectums of 12 patients with IBS and 32 healthy controls. Study participants reported their perceptions of their rectums filling, their desire to defecate, and their need to defecate. All three of these thresholds were significantly lower in people with IBS. In a similar study, subjects with IBS had a lower discomfort threshold than control subjects. These results support excessive intestinal sensitivity or activity as possible reasons people with IBS often feel unusual discomfort or have a sudden need to defecate in response to a normal meal or a small amount of gas in the colon.
IBS AND GENDER
It isn't known why so many more women than men suffer from IBS - 70% of people with the condition are women - but pain perception may be part of the answer. Studies have shown that women have lower thresholds of pain tolerance than men do in response to gastrointestinal discomfort; they may be more likely to seek help from a doctor. Female hormones also may play a role. Women with IBS report constipation in the weeks between ovulation and menstruation, when levels of estrogen and progesterone are on the rise. A sudden onset of diarrhea occurs for many women at the onset of menstruation, when progesterone levels fall and levels of prostaglandin, which stimulates the colon to contract, rise.
No single diagnostic test exists for IBS. Instead, doctors determine if a patient's symptoms fall within a certain set of criteria. The first criterion is abdominal pain or discomfort relieved with a bowel movement or accompanied by a change in the frequency or consistency of stools. Second, a varying pattern of defecation should exist at least 25% of the time and have at least three of the following characteristics: 1) altered stool frequency; 2) a change in bowel movement form - hard or loose and watery; 3) altered passage of bowel movement - straining, urgency, or feeling of incomplete evacuation; 4) passage of mucus; and 5) feeling bloated. A person is diagnosed with IBS if these symptoms have persisted for at least three months.
The doctor also will take a medical history and ask about dietary, emotional, and psychological triggers. He or she also should order tests to rule out other medical conditions such as infection, inflammation, tumors, or cancer.
The diagnosis itself of irritable bowel syndrome should be something of a relief: IBS does not cause any permanent harm to the intestines and will not progress to anything more serious. Even though there's no known "cure" for IBS, once the diagnosis is made, there are many treatment options.
TREATING IBS: DIETARY CHANGES FIRST
Foods to avoid. Certain trigger foods, such as dairy products, exacerbate symptoms of IBS. Keep track of foods that affect you. If you're prone to diarrhea, it may help to give up caffeine. Avoid excessive alcohol. Everyone with IBS should be aware that vegetables such as beans, cabbage, and broccoli are gas-producing.
Types of meals. Because eating causes colon contractions, people with IBS often have cramps and feel the urge to defecate soon after eating a meal. The amount of fat and calories in a meal determines the strength of the contractions, so it's a good idea to aim for low-fat, low-calorie meals. You might also try having several small meals throughout the day, rather than a few large meals.
For diarrhea and constipation. Antidiarrheal agents such as loperamide (Imodium) or bismuth salicylate (Pepto-Bismol) can help stop diarrhea. Cisapride (Propulsid) is often suggested for constipation, but the FDA recently issued a warning that some patients may be at risk for rare but serious cardiac events as a result of taking cisapride. If you're currently using cisapride, check with your doctor.
For cramps and pain. Smooth muscle relaxants or antispasmodic medications such as dicyclomine (Antispas) may ease cramping or abdominal pain. In addition, physicians now frequently prescribe tricyclic antidepressants such as amitriptyline (Elavil), imipramine (Tofranil), or doxepin (Adapin) to patients with severe IBS -related pain, generally at dosages much lower than those used to treat depression.
A new drug. The FDA recently approved alosetron hydrochloride (Lotronex) for women with IBS in whom diarrhea is the primary symptom. Although its mechanism of action is not completely understood, Lotronex slows intestinal activity, perhaps by blocking serotonin activity in the enteric (gastrointestinal) nervous system. Approval of Lotronex was based on results from two 12-week, double-blinded, placebo-controlled clinical studies of a total of 1,273 non-constipated women with IBS. The drug showed a 15-20% advantage over placebo in alleviating pain and reducing stool frequency and feelings of urgency. The most frequent side effect reported was constipation. Researchers currently are analyzing longer-term data.
OTHER TREATMENTS TO CONSIDER
Alternative therapy. Peppermint oil - coated to prevent heartburn - as well as chamomile, rosemary, valerian, and ginger are reported to have antispasmodic effects, and may relieve cramping. Let your doctor know if you're taking any herbal preparations because they could negate or intensify the effects of other prescription or over-the-counter medications.
Psychological/behavioral therapy. Sometimes IBS symptoms improve with psychological and behavioral therapy. This includes cognitive-behavioral therapy, where people with IBS are taught to relate their thoughts, feelings, behavior, and environment to their symptoms in order to feel more control over their condition. Other treatment options are psychological counseling, hypnosis, biofeedback, relaxation training, and family or group therapy.
Perhaps most important to your treatment is your relationship with your primary care doctor or gastroenterologist, who should be able to help you negotiate your way through the treatment options until you arrive at the right combination for you.
For More Information
National Institute of Diabetes and Digestive and
Kidney Diseases (NIDDK)
20 Information Way
Bethesda, MD 20892-3570
American Gastroenterological Association
International Foundation for Functional
DIAGRAM: How the Colon Works. The colon, or large intestine, is 6 feet long and connects the small intestine to the anus. Fluid and indigestible particles flow from the small intestine into the colon, where they solidify into feces. Muscle contractions then move the feces down the descending colon to the rectum. Nerves, hormones, and electrical activity in the colon muscle control these activities, known as colon motility.