What is ephedrine?

In one line

Ephedrine is a substance found in the ephedra plant (ma huang) that switches on the body's 'fight or flight' nerve signals, making the heart beat faster and raising blood pressure.

What is ephedrine?
A plant ingredient that comes up in diet-pill talk
The names 'ephedrine' and 'ma huang' come up when people talk about diet pills and workout supplements. It is said to come from a plant, yet supplements containing it were banned in the United States. So what exactly is ephedrine?
In short
A stimulating substance from the ephedra plant
Ephedrine is a substance found in a plant called ma huang (ephedra), and it puts the body into a tense, excited state. As a medicine, it is used for asthma and as an injection to raise blood pressure that drops during anesthesia. Today it is both extracted from the plant and made chemically.
What is ma huang?
A small shrub that grows in the desert
Ma huang is a small shrub that grows in the deserts of northern China and Mongolia. In traditional Asian medicine, its stems were used to make people sweat and to treat chills, headaches and coughs. Ephedrine is the main active ingredient of ma huang, which is called 'ephedra' in English.
What is the sympathetic nervous system?
The nerves that get the body ready to 'fight'
When you are startled or in danger, your heart races and your body tenses up. This is the work of the 'sympathetic nervous system', which gets the body ready for sudden, big movements. Its nerve endings release a signal substance called 'norepinephrine (noradrenaline)', which passes the signal to cells in places like the heart.
What it does in the body
It switches on these signals and releases more of them
Cells have spots that only certain substances fit into, called 'receptors'. Ephedrine attaches directly to the receptors that norepinephrine uses, and it also makes nerve endings release more norepinephrine. As a result, the heart beats faster, blood pressure rises and the airways widen.
Use as a medicine
Raising blood pressure during anesthesia, and asthma
Ephedrine injections are used to raise blood pressure when it falls during anesthesia. Because it widens the airways, it was also used as an asthma medicine. However, it is used less than before, because newer drugs act more precisely on just the target spots.
Why it shows up at the gym
Supplements sold for weight loss and energy
Ephedrine and ma huang were widely sold as supplements claiming to help weight loss and boost energy. In studies, ephedrine and ma huang led to about 0.9 kg more weight loss per month than a fake pill. No study followed people for longer than 6 months.
Common side effects
More pounding heart, anxiety and upset stomach
People who took ephedrine or ma huang had more heart pounding, mental symptoms such as anxiety, and stomach upset such as nausea than people who took a fake pill. The risk of these symptoms was 2.2 to 3.6 times that of the fake pill.
Serious events
Strokes, seizures and deaths
Among the ma huang supplement side-effect reports sent to the US Food and Drug Administration, the cases judged to be linked to the supplement were reviewed. The most common problem was high blood pressure. There were also strokes and seizures, and 10 deaths and 13 cases of permanent disability were reported.
Rules
The US banned ephedra supplements in 2004
In 2004, the US Food and Drug Administration banned the sale of supplements containing ephedrine-type ingredients, saying they carry an 'unreasonable risk'. In sport, the World Anti-Doping Agency bans ephedrine during competition. If the level in urine is above the set limit, it counts as a doping violation.
Common misconception
It comes from a plant, so is it gentle?
No. It is easy to think a natural plant ingredient must be gentle, but 64% of the herbal product side-effect reports to US poison centers involved ma huang products. Yet ma huang products made up less than 1% of herbal product sales. Even though it comes from a plant, ephedrine is the same substance that switches on the fight-or-flight nerves.
Summary
A substance from ma huang that switches on fight-or-flight nerves
Ephedrine is a substance from the ma huang plant that switches on sympathetic nerve signals, making the heart beat faster and raising blood pressure. Being a natural plant ingredient does not make it gentle, and ma huang products drew far more side-effect reports than their share of sales. Related terms: sympathetic nervous system, norepinephrine, clenbuterol.