Bitter orange is derived from a variety of citrus trees and their fruits. It been used traditionally in essential oils, perfumes, and flavoring. As an herbal medicine, it is used as a stimulant and for appetite suppression, as well as to treat congestion. Bitter orange has replaced the banned stimulant ephedra in many herbal weight-loss products. The key compound is synephrine, which has been found to increase heart rate and metabolism. While bitter orange has not gone through extensive safety testing, it seems to have some of the same side effects as ephedra, and has been linked to stroke, angina, and ischemic cholitis. It is presently unclear whether bitter orange is effective in promoting weight loss.