Isotretinoin, a treatment for severe acne, has been linked to inflammatory bowel disease (IBD) in some case reports and 1 study. To investigate whether isotretinoin can induce IBD, French researchers conducted a 2-year nationwide registry study.
IBD, which includes 2 separate diseases (Crohn’s disease [CD] and ulcerative colitis [UC]), is thought to be caused by a combination of genetic and environmental factors. Earlier studies show that certain medications, including antibiotics, nonsteroidal anti-inflammatory drugs, and hormonal therapies, may increase the risk of developing IBD. Despite the fact that a case-control study and several case reports suggest an association between exposure to isotretinoin and occurrence of IBD, the relationship remains uncertain.
Researchers in France evaluated the association between chronic IBD and exposure to a common treatment for severe acne, isotretinoin. Investigators examined records collected between the beginning of 2008 and the end of 2010 through the French National Health Insurance system.
Over the 2-year period, just 0.3% of 7593 patients with a diagnosis of IBD had received isotretinoin. By comparison, a separate survey of the general population found that, of 140 people with IBD, 0.4% had a history of isotretinoin exposure.
Although this result would seem to suggest a lack of association between isotretinoin exposure and IBD, investigators performed another analysis, separating the patients into 2 groups: those who had experienced UC, and those who had experienced CD. Examining each type of IBD individually resulted in a paradoxical conclusion—isotretinoin did not significantly affect the risk of developing UC (odds ratio [OR] = 1.36 [95% CI: 0.76-2.45]) and decreased the risk of developing CD (OR = 0.45 [95% CI: 0.24-0.85]).
Despite these findings, the effect size is small. A decrease in the risk of UC from 0.4% to 0.3% indicates that approximately 1000 people would need to switch from no therapy to isotretinoin therapy to induce 1 additional case of UC. Likewise, the protective effect against CD is small. A decrease in the risk of developing CD from 0.5% to 0.4% indicates that approximately 1000 people would need to avoid taking isotretinoin to prevent 1 case of UC.
This large registry study suggests that patients taking isotretinoin who ask about the potential adverse event of IBD should be assured that the risk of developing UC is not increased in patients taking isotretinoin, and exposure to isotretinoin may even exert a slight protective effect against CD.