Richard Kessinger loves to hit the gym. But some days he needs a little something to get him pumped up for his weightlifting routine.
"You might be a little bit sore. You might be tired. You might have had too many beers the day before," says Kessinger, 23, of Arlington, Va. "So you might start putting up a set and you get a few reps in and you're like, 'I'm not feeling this. I can't keep going.' "
So Kessinger sometimes swallows something called DMAA, which is short for dimethylamylamine. It's also called geranium extract because it supposedly can be found in geranium plants in China. Kessinger says it gives him the little burst of intensity that he needs.
"I just use it as a stimulant get a little extra energy boost, a little focus boost before my workout. It just gives you a little extra kick," Kessinger says.
Sometimes Kessinger takes it just to go to work.
"If I have a day that's dragging at the office it creates a little elevated mood a sort of happy feeling," he says.
Kessinger is far from alone. Americans spent more than $100 million on products containing DMAA in 2011, according to the Nutrition Business Journal, which monitors the dietary supplement industry.
But the widespread use of products containing DMAA is raising widespread concern.
"This is the most dangerous ingredient sold today in supplements in the United States," says Dr. Pieter Cohen, an internist at Harvard Medical School.
Cohen says DMAA is a potent stimulant. It drives up heart rate and blood pressure, which means it can cause many health problems.
"The common ones would be anxiety, panic attack, dehydration, and the life-threatening ones would be bleeding strokes and death sudden cardiac death," Cohen says.
The Food and Drug Administration has received at least 60 reports of complications in people using DMAA, including at least two deaths. The U.S. military barred base stores from selling DMAA supplements after two soldiers died while taking them. DMAA was recently linked to the death of a British marathon runner.
Cohen and others question whether DMAA should even be considered a "natural" ingredient.
"There's a few questionable studies that found trace amounts of this in one species of plant from China. And there's over half a dozen meticulously done academic studies that studied the same plant and found no DMAA," Cohen says.
Companies selling DMAA products dispute the criticisms.
"Among the dietary ingredients with which I'm familiar, this is probably the single most-studied," says Peter Hutt, a lawyer who advises USPLabs, a Dallas company that makes Jack3D, the most popular DMAA supplement. "It has approximately the same stimulant capacity as two cups of coffee."
The only time DMAA presents a problem is when users take too much, mix it with alcohol and drugs, or use it under extreme conditions, Hutt says.
"If someone went out, as some people have, in 102- to 105-degree temperatures, and conducted strenuous stress testing for hours. And if they were overweight and took more of the product than labeled than, yes, there have been problems," Hutt says.
Some other scientists share that view.
"Those who use a recommended and relatively low dose experience little if any problems," Richard Bloomer, of the University of Memphis in Tennessee, wrote in an email. "Those who choose to abuse the ingredient at extremely high dosages may have cardiovascular distress such as hypertensive response, etc."
But Harvard's Cohen says supplement companies should have to prove their ingredients are safe before they're allowed on the market.
"DMAA is really a poster child for why the laws governing supplements aren't working," says Cohen, who wants the FDA pull DMAA off the market.
The FDA has sent warning letters to companies selling DMAA products without providing safety information to the agency. The FDA also questions whether DMMA is a natural ingredient that qualifies as a supplement ingredient. In fact, it appears to be identical to a drug once marketed as a decongestant.
"This is something [where] someone just repurposed an old drug and felt like they could market it and sell it as a dietary supplement," said Daniel Fabricant, director of the FDA's Division of Dietary Supplement Programs. "That is something that should be concerning to everybody."
For his part, Kessinger says he thinks DMAA is for people like him healthy people who use it carefully.
"I don't think it should be illegal for me to buy," Kessinger says. I think that an educated person can use it safely and avoid having any issues with it."
He worries that supplement companies will start selling alternatives that turn out to be riskier. "They're turning to substances that are potentially even worse than DMAA," Kessinger says.
Some companies have started taking DMAA out of their supplements. And Fabricant says the FDA could take more aggressive steps if others keep selling it. But in the meantime, products containing DMAA are still easy to find.