Ketamine got its start in Belgium in the 1960s as an anesthesia medicine for animals. The FDA approved it as an anesthetic for people in 1970. It was used in treating injured soldiers on the battlefields in the Vietnam War. Emergency responders may give it to an agitated patient who, for example, they have rescued from a suicide attempt. That’s how Ken Stewart, MD, says doctors began to realize that the drug had powerful effects against depression and suicidal thoughts.

“Someone is trying to jump off a bridge and they give him ketamine in the ambulance to calm him down and 9 months later, he says, ‘I haven’t felt suicidal for 9 months.’ “When enough stories like that started to pile up, doctors said, ‘Maybe there’s something here,’” says Stewart, an emergency physician and founder of Insight Ketamine in Santa Fe, NM. Like the drug itself, Stewart got his start in combat medicine during the Vietnam War. Some doctors also use ketamine to treat suicidal thoughts.

Ketamine causes what doctors call a “dissociative experience” and what most anyone else would call a “trip.” That’s how it became a club drug, called K, Special K, Super K, and Vitamin K among others. Partiers inject it, put it in drinks, snort it, or add it to joints or cigarettes. But the drug’s potential as a treatment for depression and antidote to suicidal thoughts has drawn researchers’ attention. They’ve studied and administered it in controlled, clinical settings to help with treatment-resistant depression and other conditions.

To be clear: Casual use is not a treatment for depression. But doctors have developed a protocol for medically supervised use that may help people who don’t get relief from other medications. “We’re reaching out in a new way to patients who have not responded to other kinds of treatments and providing, for some of them, the first time that they’ve gotten better from their depression,” Krystal says.