How does ephedrine work?

The exact mechanisms are not fully understood but both ephedrine^[1][2] (the drug) and ephedrine-type alkaloids^[3][4] (from Ephedra plants) activate various adrenergic receptors in multiple tissues (heart, lungs, blood vessels, adipose tissue, muscles, etc.). This increases sympathetic nervous system activity, causing heart rate and blood pressure to rise and bronchioles in the lungs to dilate. The role of ephedrine and ephedra supplements in weight loss is likely related to increased fatty acid release from fat stores (adipose) and increased whole-body fat oxidation and energy expenditure.^[5][6][7] Because a rise in energy expenditure would increase heat production (thermogenesis), this likely explains the increased sweating caused by ephedrine and ephedra supplements.