Experts have already spent plenty of time figuring out how DCS works. It’s been around since the 1960s, when it was used to treat tuberculosis. Now, however, researchers are more excited about the drug’s potential ability to alleviate symptoms of depression, schizophrenia, obsessive-compulsive disorder and, of course, PTSD — without a lifetime of pill-popping.

“Most drugs, you dose every day,” Rothbaum says. “But DCS is only useful during exposure therapy, so you’re taking the drug right before the session. And when your series of sessions end, the medication ends too.”

DCS seems to enhance the brain’s learning process. For PTSD treatment, the drug could, ostensibly, help patients more quickly internalize that, say, driving down a suburban American highway is far different — and less dangerous — than driving on a Baghdad street. The drug also binds to receptors in the amygdala, the region of the brain that governs fear response. So by blocking out fearful reactions while a patient revisits trauma, experts think DCS can, literally, “extinguish” fear right at the source.