Since the US Food and Drug Administration banned the use of dietary supplements containing ephedra in February 2004, numerous "ephedra-free" weight-loss products have appeared on the market. Many of these supplements contain compounds such as bitter orange that are similar in structure and action to ephedra. We describe a patient in whom ischemic colitis developed 1 week after initiation of a bitter orange-containing weight-loss supplement. The patient had no other predisposing factors, and discontinuation of the supplement led to immediate improvement and ultimate resolution of her symptoms. Both consumers and health care professionals should be aware of the potential harm that bitter orange-containing dietary supplements can cause and report such adverse events to the US Food and Drug Administration.