Ephedra was banned in the U.S. in 2004 because of harmful cardiovascular effects. But "ephedra-free" products are not necessarily stimulant-free. "Bitter orange" (citrus aurantium) is used in some products in place of ephedra. This substance, especially in combination with caffiene, often causes a stimulant effect similar to ephedra leading to heart-related side-effects.
PositiveTip: Small dietary changes that add up to cut 250-500 calories and 2-3 blocks of fifteen minute walks daily are much safer and more reliable for weight loss.