It's a winter weekday afternoon in the North London neighborhood of Highbury, and Steve Ludwin, a former rock frontman who used to play the same festivals as Nirvana and Pearl Jam, is sitting on his couch in a T-shirt and jeans, flicking the barrel of a syringe, needle pointed up, releasing air bubbles from the amber liquid. To set the mood, he has cued up AC/DC's "Inject the Venom," and lead singer Brian Johnson is urging him on. Inject the venom, inject it all, stick it in, stick it . . .

"The first time I heard the chorus, I thought, 'This song is written for me,'" Ludwin says, then turns to his left forearm, sticks it with the needle, and presses the plunger, his fingers trembling. He grimaces, and a second later his face goes from English-summer pale to ghostly white. "I'm an idiot," he says through gritted teeth. "I think I hit a vein."

If the syringe had been filled with heroin, injecting it into the bloodstream would have been the goal. But Ludwin has shot a cocktail of deadly venom from two green pit vipers and a North American copperhead, which he had meant to inject subcutaneously. For the next 45 minutes, a searing pain spreads from his arm to his fingertips. Performed properly, his regular venom injections often leave him with a "burning sensation, like being stung by a hundred hornets" for a few minutes. They cause swelling and bruising; the day after shooting he feels "kind of ropey, almost hungover." But for Ludwin, the rewards outweigh the seemingly substantial risk. All told, Ludwin has access to 22 slithery pets—most of them highly venomous—and they're coiled in glass tanks downstairs from his Victorian row-house apartment.

Ludwin, 47, has fueled himself with snake venom for more than half his life. He originally sought to build up an immunity to it (and nothing more), but in 2001, he started gargling with venom while his punk-rock band Little Hell was on tour with Placebo: "It seemed to burn out the sore throat everyone else was getting." It made him see his habit in a whole new way. Now Ludwin's on a mission—part scientific inquiry, part journey of self-discovery, part shamanic quest. "I want to know why I was born with the drive to do this thing, because it started when I was very young," he says. Born in Northern California on Travis Air Force Base (his dad was a pilot), Ludwin grew up in suburban Long Island and Connecticut. He remembers, at age 4, seeing a milk snake sliding through the grass and thinking, "That's the most beautiful thing I've ever seen." At 17, he heard an "inner voice" that told him "to experiment with venom, as it would be 'good for the future.'" When he moved to London at age 20 to pursue his one dream of being a rock singer, another came true: He found work at a reptile supplier to zoos and universities, where, he says, "I suddenly had access to any reptile I wanted."

What he wanted was snakes—and their venom never gave him pause. Ludwin's drug of choice is a marvel of evolution. When a venomous snake bites its prey, it delivers a complex mix of proteins and enzymes that can attack muscle tissue, interfere with blood clotting, or cause paralysis or death. But Ludwin may have injected his way to a revolutionary discovery. In what he suggests is a literal case of that which does not kill us makes us stronger, Ludwin believes that his biweekly shots (into his torso, arms, and legs) may have made him a medicinal miracle—protecting him against infection and disease, boosting his energy and strength, and slowing down the aging process. "It's a Jane Fonda workout for my immune system," he says. "This is going to be my ninth winter without having a sore throat or a cold. I don't want to use the word supernatural, but it feels weird, like I stumbled over something."

Has Ludwin concocted his own brand of snake oil, or has he discovered the elixir of life? Perhaps a bit of both. There are a number of drugs derived from snake venom that treat heart disease, Alzheimer's, arthritis, and diabetes. Syn-Ake, a synthetic chemical that replicates part of a Malaysian temple viper's venom, is marketed as an antiwrinkle agent. (It's known in the U.K. as "Botox in a bottle.") Stephen P. Mackessy, a professor of biology at the University of Northern Colorado and a snake-venom expert, says there have been "success stories involving compounds of venom." But he stresses the difference between the "minor components" contained in trial-tested drugs and Ludwin's water-diluted pure serum: "Let's just hope we don't find Ludwin dead on the floor one day."

Five years ago, Ludwin did come close to death after shooting a syringe full of undiluted venom from a Northern Pacific rattlesnake, an eyelash viper, and a white-lipped tree viper. He had intended to inject his usual drop, but the plunger got stuck and the chamber drained into his system. Ludwin's hand swelled "to the size of a baseball mitt" and his arm turned black. After a night of excruciating pain, Ludwin checked himself into a hospital, where doctors told him he was not only going to lose his arm, he was going to die. But after three days, Ludwin regained slight movement in his fingers—thanks, he believes, to his years of venom intake. Against his astonished doctors' advice, he checked himself out in true rock-and-roll style: "I ripped the tubes out of my arm and blood squirted all over the room." The question is: Were the orderlies cleaning up just another messy pool of blood, or was it priceless scientific gold?