Until May 2004, ephedra was sold commercially as an energy booster, weight-loss supplement, and athletic performance enhancer. Although some scientific evidence suggests that this herbal supplement may improve weight, the information overall regarding its effectiveness for weight loss, energy, or athletic performance has been inconclusive and controversial. In addition, ephedra-containing products sold for these purposes have been linked to many cases of stroke, heart arrhythmia (irregular heart rhythm), and even death. Several of these products also contain caffeine; the combination of ephedra with caffeine dramatically increases the chances of adverse side effects.