A synthetic form of Japanese hornet spit is growing in popularity among endurance athletes.

When it comes to staying ahead of the competition, people will try nearly anything, as evidenced by recent doping scandals in professional American sports.

Instead of injecting themselves with bull testosterone, some athletes are now using the synthetic version of hornet vomit to gain an edge.

The larvae of the Japanese giant hornet, Vespa mandarinia, regurgitate a high-energy cocktail that allows adults to fly at 25 miles an hour over distances of 60 miles. The juice is produced by the larvae after they’ve been fed the chewed-up flesh of their parents’ prey.

A synthetic form of this vespa amino acid mixture, or VAAM, is being marketed as a nutritional supplement for athletes who want sustained energy for marathons and other high-endurance sports. Here’s what’s in it.

But before you shove your fist into the hornet’s nest for a boost, know that these “hornets from hell” are about the size of a pocketknife and have an excruciating painful sting akin to getting stabbed with said knife.

Like all other energy-boosting products, the effectiveness of VAAM is predominantly supported by anecdotes and marketing claims. Most of the studies on the substance were done more than a decade ago, and their validity is questionable.

A 2011 study found that using VAAM combined with 90-minutes of exercise twice a week increased aerobic fitness and decreased abdominal fat in sedentary women in their 60s.

Japanese long-distance runner Naoko Takahashi won an Olympic gold medal at the 2000 Olympics in Sydney and set record time of 2:23:14. She attributed her success to the use of the giant hornet juice, and since it’s 100-percent natural, it didn’t violate Olympic anti-doping laws.

Marketed and sold under the brand name Hornet Juice, VAAM costs about $2.50 a serving and can be ordered online from the New Zealand manufacturer. A much more expensive version is sold in the U.S. as Vespa CV-25.

VAAM has not been investigated or safety tested by the U.S. Food and Drug Administration or any other government agency and should be treated the same way as any other nutritional supplement—talk to your doctor before you take it.

Stuntman Bobby Holland Hanton has stepped in for, among others, Batman, Thor, and James Bond. When sharing his health tips with Healthline, he said green tea and a shot of espresso a half hour before a workout are more than enough to keep him juiced-up.

For sustained energy during the long haul, Runner’s World recommends loading up on whole grains, nuts, and dark leafy vegetables beforehand. During your race, snack on nuts, dark chocolate, or energy bars.

Don’t forget to have a banana or another potassium-rich food after you exercise to prevent muscle cramping.