Ma huang, Chinese ephedra, was used to treat asthma, or at least wheezing, five thousand years ago.
The Herbal Classic of the Divine Plowman described it as an herb of “middle class,” referring to its perceived usefulness rather than to a social standing. It has been part of the Chinese herbal pharmacopoeia ever since, and Chinese scientists (K. K. Chen and his colleagues) did some of the early research into its pharmacology early in the twentieth century.
The active component isolated from E. sinica, ephedrine, was a staple of standard medical management of asthma in the United States for several decades.
Although it has been replaced for the most part with newer synthetic compounds, ephedrine is still available over the counter for nasal congestion (as a spray or jelly) and in capsules with or without prescription as a bronchodilator.
There are many species of ephedra, but not all of them contain ephedrine or other active compounds. A native of the American Southwest, E. nevadensis, or Mormon tea, is one that does not.
The part of E. sinica that is used is the dried stem. The roots and the fruits have little or no ephedrine or other alkaloids.
The primary active ingredient of ma huang is ephedrine, accounting for 80 to 90 percent of the alkaloid content of the plant.
It also contains related chemicals, such as pseudoephedrine, which is also used in medicines to relieve nasal congestion.
In China, ma huang was used traditionally to cause sweating and to treat colds and other nasal congestion (most likely due to allergy). E. sinica could still be used to treat coughs and colds, but the synthetic derivatives are readily available in easily controlled doses.
Ephedrine is still used sometimes to treat an acute attack of asthma.
Ephedrine relaxes bronchial muscle but constricts small blood vessels in the arms and legs. This raises blood pressure, an action that is sometimes put to use in treating shock.
Ma huang can lower body temperature, stimulate the brain, and inhibit inflammation. In China, it is one ingredient in a common cold medicine. It also has antiviral and diuretic activity.
Although it has been promoted for weight loss and to improve athletic performance, it has not been shown effective for either purpose, and adverse reactions can be serious.
The dose of ephedrine for an adult is 25 or 50 mg, two or three times daily.
Herbal preparations are expected to deliver a slightly lower dose, equivalent to 15 to 30 mg total alkaloid, calculated as ephedrine.
Frequent use of ephedrine or ma huang reduces its effectiveness as a bronchodilator.
Ephedrine can cause uterine contractions; pregnant women should avoid ma huang.
Ma huang can raise blood pressure and accelerate heart rate. Persons with elevated blood pressure or heart disease should not use this herb.
Men with prostate enlargement must avoid ma huang, which can aggravate the condition.
Ma huang is not appropriate for people with glaucoma or pheochromocytoma.
Diabetics should not take ma huang because it complicates blood sugar control.
People with Graves’ disease or other hyperthyroid conditions should forgo ma-huang because it can increase metabolic rate and, after four weeks of use, alter the conversion of T4 to T3.
Ma huang may depress the appetite and should not be taken by people with anorexia.
People with insomnia, anxiety, or suicidal tendencies may suffer from possible psychological reactions to this herb.
It may also reactivate stomach ulcers in susceptible individuals.
Ma huang and ephedrine are forbidden by the International Olympic Committee.
Headache, insomnia, nervousness or agitation, and dizziness are all potential reactions to ma huang or to ephedrine. It can raise blood pressure and trigger heart palpitations.
Restlessness, vomiting, and difficult urination are additional side effects. Skin reactions indicating sensitivity have been reported.
At high doses, the rise in blood pressure can be alarming. Heart rhythm disturbances may occur, and toxic psychosis is considered possible.
After several deaths were linked to overuse or abuse of ma huang, the FDA restricted its availability.
Excess nervous stimulation may occur if ma huang is taken together with caffeine (including guarana, coffee, or tea) or theophylline. Such a combination is also likely to provoke cardiovascular reactions.
Ma huang must not be combined with MAO inhibitors such as Nardil or Parnate. This interaction could send blood pressure dangerously high. Allow at least two weeks to elapse after stopping an MAO inhibitor before taking ma huang.
Ma huang is incompatible with cardiac glycosides such as Lanoxin and with the anesthetic halothane. Serious disruption of heart rhythm may occur.
Ma huang must not be combined with ergot or its derivative ergotamine, or blood pressure could become very elevated.