Synephrine is a stimulant, similar to caffeine and ephedrine. It increase the metabolic rate without affecting heart rate or blood pressure. Synephrine releases adrenaline and noradrenaline only in the beta-3 receptor sites (mostly adipose tissue and the liver). Stimulation of the beta-3 receptor sites elicits the breakdown of lipolysis (fat). It is thought to have similar effects in terms of providing an energy boost, suppressing appetite and increasing metabolic rate leading to the burning or more calories.

Synephrine is alike in chemical structure and function to ephedrine, even though the stimulatory effects elicited from this product tends to be milder. Synephrine does not cross the blood-brain barrier and directly stimulate the central nervous system.

Synephrine 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 Zhishi.