Synephrine is a biogenic amine derived from the Citrus aurantium fruit, which is used for a variety of reasons in Traditional Chinese Medicine. It can be used both to aid in fat loss and as an appetite suppressant and animal models indicate that it may aid in alleviating depression.

The mechanism of action of synephrine is relatively unique among weight loss aids. Synephrine is an agonist of the alpha(1) adrenoreceptor [1-2], which is involved in many physiological processes. This adrenoreceptor plays a variety of roles in adipose tissue, such as modulating intracellular Ca2+ and protein kinase C levels and glycogenolysis and lactate production [3]. Correspondingly, alpha(1) agonists increase lipolysis in a variety of experimental paradigms [3-6], including an in vivo increase in lipolysis in human white adipose tissue [4]. This effect is potentiated by beta receptor stimulation, adenosine antagonism, and elevated cAMP levels [5-7], so ephedrine, caffeine, and forskolin may all be synergistic with synephrine. The appetite suppression caused by some agents is also known to be due to alpha(1) agonism [8], so synephrine can also be expected to aid in a fat loss plan in this regard.

The dosage of synephrine typically used is 10-20 mg daily, although some use as much as 50 mg daily. It is recommended to start with a low dose and work up, and exercise caution when combining synephrine with stimulants. Synephrine should not be taken if one is taking an MAO inhibitor or blood pressure medication.