Mephentermine, sold under the brand name Wyamine among others, is a sympathomimetic medication which was previously used in the treatment of low blood pressure but is mostly no longer marketed.

[4][5] Side effects of mephentermine include dry mouth, sedation, reflex bradycardia, arrhythmias, and hypertension.

[4][7][8] Misuse of mephentermine for recreational and performance-enhancing purposes has been increasingly encountered in modern times, especially in India.

[citation needed] The most common side effects of mephentermine are drowsiness, incoherence, hallucinations, convulsions, slow heart rate (reflex bradycardia).

[citation needed] Potentially fatal reactions are due to atrioventricular block, central nervous system stimulation, cerebral hemorrhage, pulmonary edema, and ventricular arrhythmias.

[citation needed] Potentially fatal drug interactions are the risk of abnormal heart rhythm in people undergoing anesthesia with cyclopropane and halothane.

[5][6] Mephentermine appears to act by indirect stimulation of β-adrenergic receptors through causing the release of norepinephrine from its storage sites.

It dilates arteries and arterioles in the skeletal muscle and mesenteric vascular beds, leading to an increase in venous return.

[citation needed] Mephentermine, along with phentermine, is known to be produced as a metabolite of the orally administered local anesthetic oxetacaine (oxethazaine).

[2][7][9] Brand names of mephentermine include Wyamine (USTooltip United States), Fentermin (PTTooltip Portugal), and Mephentine (INTooltip India).

[5] Misuse of mephentermine for recreational and/or performance-enhancing purposes has been reported along with addiction and dependence and serious health complications.

[27][26] Mephentermine was evaluated in the treatment of congestive heart failure in one small clinical study but was found to be ineffective.