Ephedra is also known as Ma Huang or Desert Tea. Although popularized within the last decade, it has been used for thousands of years for its remedial powers. Ephedra is a small evergreen shrub that grows to heights approaching 20 inches. It has long narrow stem with very small leaves. This shrub is native to Northern China and parts of Mongolia. It is most often found in desert climates because it grows best in well-drained soils. The stems of the ephedra shrub can be harvested throughout the year and dried for medicinal preparation. 
Ephedra has documented use as a Traditional Chinese Medicine (TCM), dating back over 4,000 years. As a TCM remedy, it was used to disperse cold symptoms and to aid in movement of the lung Qi - a pattern of illness in Chinese medicine. It was also used for conditions ranging from fever and chills, to promoting calmness and relaxation.
In Western medicine, Ephedra has been rigorously studied, especially its key constituent ephedrine. Since the discovery of ephedrine, most of ephedra’s usage pertains to this isolated constituent. It remains a common remedy for cold symptoms and is included within most decongestant medications (i.e. pseudoephedrine). Ephedrine may be employed for cough, bronchitis, asthma, and hay fever.
The key constituents in Ephedra include the alkaloids - ephedrine and pseudoephedrine, tannins, saponins, flavones, and volatile oils.  The majority of nutritional supplements are standardized with alkaloids because of their wide use as a decongestant. The alkaloids are also commonly used for weight loss or in weight loss products, but are paralleled with the potentiality of abuse.
Ephedrine increases the metabolic rate of fat cells, dilates the bronchioles, and increases the heart rate by stimulating the adrenergic receptors. It can also stimulate the Central Nervous System, or CNS. When administered, ephedrine acts similar to epinephrine, or adrenalin, in the body. Pseudoephedrine acts similarly to ephedrine, but with less action on the heart and lungs. Both constituents stimulate the adrenal glands to release norepinephrine, and may cause adrenal exhaustion, which can result in long-term consequences.
The part of the Ephedra plant that is used medicinally is the stem. It can be used fresh or dried.
It is used primarily used for weight loss via increases in metabolic rate increases caused by its associated stimulating activity. It was also widely used for asthma, and as an effective decongestant for the common cold and seasonal allergies.
Other less well know uses for Ephedra are as a diuretic, diaphoretic (causes sweating), and to raise the blood pressure.
The usual dosages for Ephedra are as follows:
10 - 25 milligrams (mg) of the alkaloids (i.e Ma Huang) daily
1 - 4 grams, three times daily as a tea
6 - 8 milliliters, three times daily as a tincture (1:4)
In the United States the sale of any product with more than 10 mg of Ephedra is currently restricted.
Side effects of Ephedra include anxiousness, restlessness, insomnia, headache, nausea, vomiting, heart palpitations, high blood pressure, increased heart rate, and urinary disorders. Because of the serious side effects, Ephedra should only be taken in low doses (10 mg or less).
An overdose of Ephedra can cause severe sweating, enlarged pupils, muscle spasms, increased body temperature, heart failure, liver inflammation, and death due to suffocation. These preliminary findings, however, need more extensive research to be completely validated.
Ephedra is contraindicated in people with glaucoma, benign prostatic hyperplasia, urinary disorders, prostate cancer, over active adrenal gland, thyroid disorders, kidney disorders, diabetes, heart disease, seizures, and/or psychiatric disorders.
Ephedra has the potential to interact with many medications, due to its mechanism of action. It should not be combined with other steroids for asthma, digitalis, guanethidine, MAO inhibitors, ergot drugs, and/or Eldepyrl. 
1. Chevallier A. Encyclopedia of Herbal Medicine, 2nd Ed.; 2000. Dorling Kindersley, New York: 97.
2. Chevallier A. Encyclopedia of Herbal Medicine, 2nd Ed.; 2000. Dorling Kindersley, New York: 97.
3. http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/101840.shtml Ephedra. February 2005.