There is now ample evidence(what evidence?) that synephrine produces most of its biological effects by acting as an agonist (i.e. stimulating) at adrenergic receptors, with a distinct preference for the α1 over the α2 sub-type. However, the potency of synephrine at these receptors is relatively low (i.e. relatively large concentrations of the drug are required to activate them). The potency of synephrine at adrenergic receptors of the β-class (regardless of sub-type) is much lower than at α-receptors. There is some evidence that synephrine also has weak activity at 5-HT receptors, and that it interacts with TAAR1 (trace amine-associated receptor 1).