White fluid drips out of a cactus-like plant in the mountains of Morocco. DON’T touch it. DON’T breathe nearby. In fact, you may want to stand far, far away. This milky plant-stuff is 10,000 times hotter than the Carolina reaper, the hottest pepper in the world! Could something so hot actually be good for people? Scientists think so.

The white fluid is called latex. It comes from the plant Euphorbia resinifera. The molecules inside, resiniferatoxin (RTX), are 4.5 million times hotter than a wimpy jalapeño pepper. You would think twice before popping a jalapeño into your mouth. Jalapeños are full of a compound called capsaicin. Capsaicin turns on nerves in your mouth that send this message to the brain: “My tongue is on fire!” Your tongue isn’t actually on fire, of course—but it sure feels like it is! RTX belongs to the same family of molecules as capsaicin. But it sends a much stronger message. In fact, it kills nerve endings!

“Killing nerves” doesn’t sound like a good thing, does it? But it may have a beneficial side. RTX kills only some nerves. And doctors find that useful. Imagine this: A patient with knee pain that never stops gets an RTX injection in the sore joint. Before giving the injection, a doctor puts the patient to sleep with anesthesia. Good thing! RTX will cause lots of pain while it harms the pain-sensing nerves. RTX binds to the nerves that sense pain—not the ones that feel light touch or tell the knee to bend. Soon the patient wakes up. The patient can walk. He or she can feel someone touching the knee. But the knee gives no pain.

Morocco’s plant could give people a major “ouch!” But it can also give a majorly-relieved “ahhhh…”