Ephedrine was first isolated in 1885 and came into commercial use in 1926.It is on the World Health Organization’s List of Essential Medicines. It is available as a generic medication.It can normally be found in plants of the Ephedra genus.Dietary supplements containing ephedrine are illegal in the United States,with the exception of those used in traditional Chinese medicine, where its presence is noted by má huáng.
Ephedrine is a non-catecholamine sympathomimetic with cardiovascular effects similar to those of epinephrine: increased blood pressure, heart rate and contractility. Like pseudoephedrine it is a bronchodilator, with pseudoephedrine having considerably less effect.

Ephedrine may decrease motion sickness, but it has mainly been used to decrease the sedating effects of other medications used for motion sickness.

Ephedrine is also found to have quick and long-lasting responsiveness in congenital myasthenic syndrome in early childhood and also even in the adults with a novel COLQ mutation.

Ephedrine is administered by intravenous boluses. Redosing usually requires increased doses to offset the development of tachyphylaxis, which is attributed to the depletion of catecholamine stores.

Weight loss
Ephedrine promotes modest short-term weight loss,specifically fat loss, but its long-term effects are unknown.In mice, ephedrine is known to stimulate thermogenesis in the brown adipose tissue, but because adult humans have only small amounts of brown fat, thermogenesis is assumed to take place mostly in the skeletal muscle. Ephedrine also decreases gastric emptying. Methylxanthines such as caffeine and theophylline have a synergistic effect with ephedrine with respect to weight loss. This led to creation and marketing of compound products.One of them, known as the ECA stack, contains ephedrine with caffeine and aspirin. It is a popular supplement taken by bodybuilders seeking to cut body fat before a competition.
Ephedrine is a sympathomimetic amine and substituted amphetamine. It is similar in molecular structure to phenylpropanolamine, methamphetamine, and epinephrine (adrenaline). Chemically, it is an alkaloid with a phenethylamine skeleton found in various plants in the genus Ephedra (family Ephedraceae). It works mainly by increasing the activity of norepinephrine (noradrenaline) on adrenergic receptors. It is most usually marketed as the hydrochloride or sulfate salt.

Ephedrine exhibits optical isomerism and has two chiral centres, giving rise to four stereoisomers. By convention, the pair of enantiomers with the stereochemistry (1R,2S) and (1S,2R) is designated ephedrine, while the pair of enantiomers with the stereochemistry (1R,2R) and (1S,2S) is called pseudoephedrine. Ephedrine is a substituted amphetamine and a structural methamphetamine analogue. It differs from methamphetamine only by the presence of a hydroxyl group (—OH).

The isomer which is marketed is (−)-(1R,2S)-ephedrine.

Ephedrine hydrochloride has a melting point of 187−188 °C.[33]

In the outdated D/L system (+)-ephedrine is also referred to as D-ephedrine and (−)-ephedrine as L-ephedrine (in which case, in the Fisher projection, the phenyl ring is drawn at the bottom).

Often, the D/L system (with small caps) and the d/l system (with lower-case) are confused. The result is that the levorotary l-ephedrine is wrongly named L-ephedrine and the dextrorotary d-pseudoephedrine (the diastereomer) wrongly D-pseudoephedrine.

The IUPAC names of the two enantiomers are (1R,2S)- respectively (1S,2R)-2-methylamino-1-phenylpropan-1-ol. A synonym is erythro-ephedrine.