“DMAA is like a poster child for why the laws do not work that regulate supplements,” he says. “It has no role to be sold as a supplement. It’s a pharmaceutical drug.” But back in 2006, the sports industry found one—since discredited—study linking DMAA to the plant geranium, and they introduced the drug into the sports supplement market.

They had another bar to pass: “Even under the lax regulatory framework, you still have to submit safety data,” Cohen says. That was never done, and the FDA didn’t do a thing until the middle of last year and still hasn’t made a ruling. As of now, “it’s completely legal to sell a supplement with any amount of DMAA in the U.S,” despite warning letters issued by the FDA. In other words, you can buy amphetamine-like pharmaceutical drugs without prescription in any dosage. To make matters worse, you can’t actually trust the label. There’s often a large gap between the listed quantities and what you’re really getting, according to Cohen.

Like Ephedra, we know DMAA doesn’t belong on store shelves. But can it kill? “It’s a true perfect storm when someone actually dies and someone can say conclusively that the supplement caused the death,” says Stuart Phillips, Ph.D., a leading researcher in the field of exercise metabolism. Deaths might not be common, but DMAA affects your blood pressure and can cause cardiac issues, he says. “Every now and again you get someone who is susceptible to those things,” and the person sometimes dies. At least that’s what some doctors speculate happened to a London Marathon runner who fueled-up on Jack3d. But the symptoms are often less severe—extreme dehydration, kidney stones (caused by the dehydration), and intense constipation, Cohen says.

So who can you trust? Are any supplements safe? It’s a buyer beware market, but you can roughly categorize your sports supplements into three groups based on efficacy and risk: The pre-workout boosters, the muscle-builders, and the recovery powders.

Pre-workout boosters include things like caffeine, DMAA, and Ephedra. According to Cohen, the only legal ingredient that works is caffeine. Just don’t buy it in supplement form; it’s cheaper and you’ll have a more accurate dose if you purchase a caffeine pill or drink a cup of coffee. About 100-200mg will likely do you well. If you pick a product that pushes the envelop—like DMAA—you’re running the risk of stroke and heart attack. “There’s no getting around it,” he says.

The problems really start to show up with the muscle-builders, Cohen says. “They’re either not going to work, or they have shady, illegal designer steroid things in them which pose the same risks” as taking the real thing—liver problems, growth of breasts, etc.

Luckily, the third category—including things like creatine and protein powder—is generally perfectly safe, according to Cohen.

CONCLUSION: It’s a buyer-beware market in the world of sports supplements. So stick to the basics: caffeine, protein, creatine, and carbohydrate powders.