Ephedra (also known as ma huang, desert tea, or mormon tea) is a small, branched shrub native to desert regions of inner Mongolia and northern China, with related species found in desert regions throughout the world. The plant has grooved, cylindrical stems, which range from 30 to 90 centimeters in height, and small, scale-like leaves, which reach two to four millimeters in length. The plant has separate male and female flowers, which grow in yellowish-green, terminal catkins, with the female catkins eventually producing a red, berry-like false fruit. The dried green stems are used for health purposes.
The active constituents in ephedra are a group of alkaloid compounds that includes ephedrine, pseudoephedrine, norephedrine, and norpseudoephedrine. The compounds work by indirectly stimulating the central nervous system.
The daily dosage recommendation for ephedra varies with the alkaloid content of the plant. For adults, Commission E recommends single doses of preparations corresponding to 15-30 mg of total alkaloid content (calculated as ephedrine), with a maximum daily dosage of 300 mg. For children, the dosage should correspond to 0.5 mg of total alkaloid per kg (2.2 lb) of body weight, with a maximum daily dosage of 2 mg total alkaloid per kg of body weight. Ephedra use has been associated with numerous side effects such as insomnia, restlessness, irritability, headaches, nausea, vomiting, urinary disturbances, accelerated heart rate, and, in higher dosages, cardiac arrhythmia and drastic increase in blood pressure. Ephedra is not recommended for use by people suffering from anxiety, high blood pressure, glaucoma, impaired circulation to the cerebrum, prostate adenoma, or thyroid disorders. Because ephedra has been shown to interact with a variety of drugs, people taking prescription medications should only take the herb under a doctor's supervision. Because of the danger of developing dependence, long-term use of ephedra is not recommended.