While suspected for some time, a study now confirms that people taking the acne drug isotretinoin appear to run an increased risk of developing inflammatory bowel disease, US researchers report.

Inflammatory bowel disease, or IBD, includes Crohn’s disease and a similar condition called ulcerative colitis. Isotretinoin, more familiarly known by the brand name Accutane, was first approved for acne in the US in 1982, and numerous cases have surfaced linking the drug to IBD. Until now, a systematic review of the association had not been conducted.

Dr. Corey A. Siegel, from Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire, and colleagues reviewed all reports of isotretinoin-associated IBD that were filed with the US Food and Drug Administration via the MedWatch system, which began in 1996.

The authors explain in the American Journal of Gastroenterology that they used a standard adverse drug reaction probability scale to grade the likelihood that a particular IBD case was, in fact, caused by isotretinoin use.

Between 1997 and 2002, a total of 85 isotretinoin-related cases of IBD were reported. In just four cases, isotretinoin was graded as a “highly probable” cause of the IBD, while in 58 cases it was deemed a “probable” cause, and in 23 cases it was seen as a “possible” cause. The link between isotretinoin use and IBD was never graded as “doubtful”.

“Physicians and patients should be made aware of this possible association and it should be included in the already extensive consent process required before isotretinoin is prescribed,” the investigators write.

The consent process covers the high risk of birth defects if a woman becomes pregnant while taking isotretinoin.

Should someone with severe acne take isotretinoin? “We do not think that this should prohibit the use of isotretinoin,” Siegel and colleagues advise. However, “careful consideration should be made” for people with a prior personal history or family history of inflammatory bowel disease, or who have symptoms suggesting the possibility of IBD.

SOURCE: American Journal of Gastroenterology, July 2006.