Inside the cozy office at Vitalitas Ketamine Infusement Center in Denver, Colorado, Dr. Roman Langston shows me where he administers ketamine IVs. Instead of wax paper-topped exam tables, patients sit in luxurious leather recliners. Their cushy armchair faces an enormous window overlooking a cluster of trees — trees which, some patients have claimed — talk to them during ketamine treatment.

Hallucinations like these are a relatively common side effect, because ketamine is a hallucinogen. In fact, it’s the only psychedelic drug a doctor can prescribe. For decades, medical use of ketamine was restricted to complex pain conditions and anesthesia. Non-medical use of ketamine was widespread, as well, as ‘Special K’ has long been a beloved club drug at concerts and raves. However, now ever-emerging research and countless successful case studies indicate the drug may be a ground-breaking new frontier for myriad mental health issues.

“Ketamine stimulates instant neuron cell growth in the brain,” Dr. Sara Markey, a psychiatrist at Ketamine Treatment Centers, also in Denver, Colorado, says over the phone. At Dr. Markey’s and Dr. Langston’s clinics, patients with depression, anxiety, OCD, PTSD, complex migraines or pain disorders can have ketamine mainlined directly into their bloodstream. And oftentimes, they can instantaneously recognize the increased activity occurring in their ordinarily tired mind.

“Patients can feel the flourishing of connectivity in their brain,” Dr. Langston says. “If you look at brain scans before and after treatment, you’ll see a remarkable difference. Before an infusion, their neurons look like a tree in winter, and after, they look like a tree in spring.”

Under the influence of ketamine, people can feel more than just mental interconnectedness. Fundamentally, ketamine is a dissociative, meaning it induces an out-of-body experience, or a sense of separation between the body and mind. “It’s like you’re watching a movie of your life, but you’re in the audience,” Dr. Markey explains. “So you can get this perspective of your life from the outside.”

How ketamine produces this surreal effect is not entirely understood. “People who say they know how it works are just speculating,” Dr. Langston says. “We don’t really know.”

Although its mechanism of action may be entirely unique, the outcomes of ketamine treatments are often compared to those of another stigmatized mental health remedy: electroconvulsive therapy. Except instead of inducing a seizure in the brain, as ECT does, ketamine creates a short-duration euphoria that leaves patients feeling like they’ve hit the reset button on their brain.

For depressed patients, these mind-altering experiences can inspire powerful epiphanies. “People have said they experience an altered perception of the universe, and of time and space,” Dr. Markey continues, “and it’s enough to make them think, ‘maybe my perception of reality isn’t the one true way of seeing things. Maybe my way of seeing things isn’t serving me.’”

For patients with PTSD, ketamine can also be particularly transformative by allowing sufferers to disconnect from deep-seated traumas. “Patients with PTSD can’t separate from their trauma and it’s always there,” Dr. Langston explains. “But on ketamine, suddenly the trauma becomes an object outside of you that you can examine in a dispassionate way.”

Ketamine’s psychological insights have sometimes come from benevolent hallucinations, too. Some of Dr. Markey’s patients have visualized comforting creatures offering life advice. Beyond allowing communication with the trees outside the clinic window, Dr. Langston’s treatments have even turned transcendental. “They’ll insist there was a higher power present during their infusion,” Dr. Langston says. “They’ll tell me, ‘God was there.’”

Given its powerful mind-altering abilities, it’s no surprise that ketamine use isn’t exclusive to legally legitimate clinics. Like any other psychedelic drug, ketamine has a thriving underground market with copious customers and suppliers.

"Seth," a recreational ketamine user, was also once a major dealer in the California nightlife scene. While his father was receiving low-cost cancer treatments in Mexico, Seth frequently flew south to care for him.

“The first time I went to some corner store pharmacy to pick up his pills, I realized I didn’t need a prescription,” Seth says. One drug that anyone could buy was ketamine. “So I’d buy a ton of little vials of liquid ketamine and walk them over the border on the bridge from Tijuana to San Diego.”

Over the course of three years, Seth estimates he ran ketamine errands to Tijuana at least 50 times. Most black-market suppliers likely share a similar strategy, as 80 percent of ketamine seized in the United States is of Mexican origin, according to the DEA.

Once the Special K was in the states, Seth emptied the little vials into his mother’s pie dishes and cooked them until the liquid ketamine turned into powder. Then, he’d sell it at raves.

“There were anywhere from 10,000 to 20,000 people at these field raves, and everyone wanted to get high on either ecstasy or ketamine,” Seth says.

Ecstasy and ketamine certainly don’t seem interchangeable — and although the sedating effects of K and the hyperactive high of E may be worlds apart, they serve a similar purpose. They both make you feel like you’re floating on clouds, make music sound orgasmic, and offer a promising new approach for the treatment of PTSD.

“Ketamine is a lot like a light-MDMA experience, but it doesn’t last as long or take a toll on the body like MDMA does,” Dr. Markey says. “MAPS, the Multidisciplinary Association for Psychedelic Studies, is currently attempting to get MDMA approved by the FDA to treat PTSD.”

But MAPS is pursuing a lot more than just ketamine treatments and MDMA therapy. “There’s a lot of exploring to be done in terms of using psychedelics to treat different types of mental health maladies,” Dr. Langston says. “I think the work that MAPS is doing is very promising.”

Whether it’s mushrooms for cluster headaches, ayahuasca for depression, LSD for pain management, or ibogaine for addiction, it seems psychedelic drugs offer untold medicinal promise.