These antidepressants, Dr. Jan Tack told Reuters Health, "could be considered in IBS patients who do not respond well enough to a classical treatment approach."

SSRIs are often used in the treatment of IBS "although evidence of their efficacy is scarce," Tack from University of Leuven in Belgium and colleagues note in the journal Gut.

They therefore compared treatment with the SSRI citalopram (brand name, Celexa) to treatment with an inactive "placebo" in 23 patients with IBS who were free of depression. They took one or other of the pills for six weeks, then switched to the other for six weeks after a three-week "washout" period.

"After three and six weeks of treatment, citalopram significantly improved abdominal pain, bloating, impact of symptoms on daily life, and overall well being compared with placebo," the team reports.

Citalopram's ability to alleviate several IBS symptoms seems unrelated to its effect on depression or anxiety, because depressed patients were excluded from the study and changes in mood did not correlate with IBS symptom improvement.

"Citalopram provided symptomatic benefit of rapid onset, was well tolerated, and was not associated with the side effects of tricyclic antidepressants, such as drowsiness or constipation," Tack and colleagues point out.