Synephrine (or oxedrine) is a drug aimed at encouraging fat loss. While its effectiveness is widely debated, synephrine has gained significant popularity as an alternative to ephedrine, a related substance which has been made illegal or restricted in many countries due to concerns about potential problems with heart disease risk and its use in methamphetamine manufacture. Synephrine is derived primarily from the fruit of Citrus aurantium, a relatively small citrus tree, of which several of its more common names include Bitter Orange, Sour Orange, and Zhi shi.