A daily dose of snake venom might be the next treatment for people with heart disease, because a particular kind stops blood cells from clumping up without also causing a dangerous side effect.

Current antiplatelet drugs prevent the clotting cells in the blood called platelets from sticking together, which helps people who have heart disease. But according to the American Heart Association, those drugs can also cause excessive bleeding, which poses a serious risk to the patients. A new drug derived from snake venom interacts with a protein in those platelets to stop them from clotting without the side effect.

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It’s a pick-your-poison kind of scenario, because some antiplatelet drugs that cause excessive bleeding are also derived from snake venom. But the effect is substantially reduced with the new treatment. A study in Arteriosclerosis, Thrombosis and Vascular Biology, a journal of the AHA, says the new drug, which is still in development, only causes “usually slightly prolonged bleeding times.”

It’s based on a protein — known as trowaglerix — in the venom of a common pit viper found in Southeast Asia, Tropidolaemus wagleri. That snake is native to Indonesia, Malaysia, Singapore, Thailand and Vietnam. It’s more commonly called Wagler’s pit viper, but is also sometimes referred to as a temple pit viper.

According to the AHA, scientists do not understand why the other venom medicines cause severe bleeding in patients. Meanwhile, the trowaglerix-based treatment has been tested in mice, which were then slower to form blood clots and “did not bleed longer than untreated mice.”

The next step is testing in other animals and then eventually human trials.

The drug developers, from National Taiwan University, are still working to make the medication last longer in the patient’s body and are tweaking the design to make sure the venom-based drug interacts only with the targeted protein on the platelet surface, called GPVI, “and not other proteins, which can cause unintended reactions,” co-author Jane Tseng said in the AHA statement.

Platelets are just one type of cell in the blood, the others being red and white blood cells. The red blood cells are the ones that carry oxygen to the tissues throughout the body, while the white blood cells are part of the body’s defenses — the immune system — and protect against foreign invaders. Our bodies use platelets to clot the blood. Our blood also contains a liquid called plasma, which is made up of water, proteins, hormones, sugar and other substances.

Read: This Drug Slashes Cholesterol Levels Better Than Any Other

Snake venom might not be the oddest substance used to create medications for heart disease. Doctors prescribe heart medications that rely on the same material that makes dynamite so explosive — in small amounts, nitroglycerin simply lowers blood pressure. Other drugs rely on the poisonous plant called foxglove, using a toxin from it to improve circulation.

There are plenty of other medications and treatments out there that have similarly deadly origins, beyond just heart disease remedies. Radiation, for example, can profoundly sicken or even kill someone in high enough doses, yet it is also a common treatment for cancer.

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