Ephedrine is a sympathomimetic amine - that is, its principal mechanism of action relies on its indirect action on the adrenergic receptor system, which is part of the sympathetic nervous system or SNS. Whilst it may have weak agonist activity at α- and β-adrenergic receptors, the principal mechanism is to displace noradrenaline from storage vesicles in presynaptic neurons. The displaced noradrenaline is released into the neuronal synapse where it is free to activate the postsynaptic adrenergic receptors.

Ephedrine's mechanism of action on neurotransmission in the brain is wide. Its action as an agonist at most major norepinephrine receptors and its ability to induce moderate stimulation of the release of both dopamine and to a lesser extent, serotonin, is presumed to have a major role in its mechanism of action.

Because of ephedrine's ability to potentiate dopamine neurotransmission it is thought to have addictive properties by some researchers.

While ephedrine's role in the serotonin system is less understood there is preliminary documentation of clinically significant agonism at excitory serotonin receptors, perhaps as a downstream response to the large release of norepinephrine in the nucleus accumbens (commonly referred to as the "pleasure center" of the brain). In mice, stereotypical behaviour was both easily induced by administration of ephedrine and it's primary alkaloids and reversed when serotonin antagonists were administered.