Irritable bowel syndrome affects 10 to 15 percent of the U.S. population to some degree. This condition is defined as
abdominal pain and discomfort with altered bowel habits in the absence of any other mechanical, inflammatory, or biochemical explanation for these symptoms.
Irritable bowel syndrome is more likely to affect women than men and is most common in patients 30 to 50 years of age. Symptoms are improved equally by diets supplemented with fiber or hydrolyzed
guar gum, but more patients prefer hydrolyzed
guar gum.
Antispasmodic agents may be used as needed, but
anticholinergic and other side effects limit their use in some patients.
Loperamide is an option for treatment of moderately severe
diarrhea.
Antidepressants have been shown to relieve
pain and may be effective in low doses. Trials using
alosetron showed a clinically significant, although modest, gain over placebo, but it is indicated only for women with severe
diarrhea-predominant symptoms or for those in whom conventional treatment has failed.
Tegaserod has an advantage over placebo in
constipation-predominant
irritable bowel syndrome; it is indicated for up to 12 weeks of treatment in women. However, postmarketing reports of severe
diarrhea and
ischemic colitis further limit its use. Herbal
therapies such as
peppermint oil also may be effective in the treatment of
irritable bowel syndrome.
Therapies should focus on specific gastrointestinal dysfunctions (e.g.,
constipation,
diarrhea,
pain), and medications only should be used when nonprescription remedies do not work or when symptoms are severe.