Thanks to legal loopholes and a patchwork of compelling research, businesses like Nushama in New York City are writing the rules as they go.The décor of the Nushama Psychedelic Wellness Clinic was designed to look like bliss. “It doesn’t feel like a hospital or a clinic, but more like a journey,” said Jay Godfrey, the former fashion designer who co-founded the space with Richard Meloff, a lawyer turned cannabis entrepreneur.The “journey,” in this instance, is brought on by ketamine, administered intravenously, as a treatment for mental health disorders, albeit one that has not yet been approved by the Food and Drug Administration.“I thought, what does bliss look like?” Mr. Godfrey said. At Nushama, which occupies the entire 21st floor of a building in midtown Manhattan, it looks like 3,000 plastic pastel flowers hanging from the ceiling, and a flat screen TV in the waiting room playing a “landscape of wonder” N.F.T. featuring lily pads and garlands of leaves that are, upon closer inspection, tiny nymphs — with wallpaper to match.Mr. Godfrey closed his fashion business and founded Nushama in 2020. He had become disenchanted with the fashion world, he said, and had been using psychedelics for his own mental health for many years after being inspired by Michael Pollan’s best-selling book “How to Change Your Mind.” The light-bulb moment — Mr. Godfrey called it “an openhearted experience” — came at the beginning of the pandemic when he realized, “I have the ability to bring these medicines to people.”It may be a calling, but Mr. Godfrey’s career pivot from fashion to wellness came as there was less of a need for the clothes he designed, and there was a ballooning interest in psychedelics as alternative treatments for mental health. Investors are banking on various psychedelic start-ups, including delivery services and luxury travel offerings. Nushama is just one example of what many see as the next frontier in health, which, thanks to legal loopholes and a patchwork of compelling research, is able to operate with limited oversight.The F.D.A. doesn’t authorize ketamine for mental health treatment, though it allows the drug to be used as a sedative, making it possible to get a prescription in New York. It has authorized a version of ketamine, called esketamine, which is administered as a nasal spray, to be used for mental health, but only for treatment-resistant cases of depression — and while esketamine contains a molecular component of ketamine, the F.D.A. says these drugs are not the same.In other words, ketamine treatment at Nushama is an “off-label” use of the drug, and representatives from the F.D.A., Federal Trade Commission and the United States Drug Enforcement Administration said they do not regulate off-label drug use, and therefore cannot comment on clinics like Nushama.“There’s nothing suspicious” about off-label prescription use in general, said Mason Marks, a senior fellow at Harvard Law School specializing in the regulations around psychedelics, but ketamine providers need to be careful about over-promising the drug’s benefits, particularly when there’s limited evidence of its efficacy. According to Dr. Dan Iosifescu, a psychiatrist at N.Y.U. Langone, ketamine is also potentially addictive, heightening the risk of using the drug, even in a therapeutic setting.There are 18 treatment rooms at Nushama, including one for couples and another for group sessions.Victor Llorente for The New York TimesThree-thousand plastic pastel flowers hang from the ceiling at the clinic.Victor Llorente for The New York TimesMany researchers and mental health professionals do consider ketamine to be effective for treating depression where other drugs have failed, but Nushama’s website says it uses the drug to treat eating disorders, obsessive compulsive disorder, addiction and chronic pain, conditions where there is far less evidence of its efficacy.“I think the ‘spa for the brain’ concept trivializes both the illness and the treatment. Ketamine is a medical treatment intended to address a significant illness,” such as severe depression or suicidal ideation, said Dr. Joshua Berman, the medical director for interventional psychiatry at Columbia University. “It has not been developed to provide diverting, relaxing or novel experiences for the bored or the worried well.”And perhaps most concerning to experts, it’s up to individual centers to determine if, and how, patients work with mental health providers.“With ketamine, there’s so much off-label use. It’s really concerning because, most of the time, it’s not administered with any psychotherapy at all,” said Natalie Ginsberg, a representative from the Multidisciplinary Association for Psychedelic Studies, a research and advocacy group. It’s critical that ketamine centers incorporate therapy throughout a patient’s process, she said.Checking InAfter making an appointment at Nushama, patients have a virtual psychological evaluation with Dr. Steven Radowitz, the center’s medical director. (Mr. Meloff said Nushama avoids the word “patients” internally, in favor of “clients” or “members.”) They turn away an estimated 10 percent of potential patients if they lack a “good foundation or support network,” struggle with substance abuse, have high blood pressure or haven’t been treated previously for a psychiatric condition, Dr. Radowitz said.Alternatively, if someone comes in with a concurrent pain diagnosis, the first appointment is with Dr. Elena Ocher, Nushama’s chief medical officer, who received her medical degree in Russia from Pavlov First Saint-Petersburg State Medical University and trained in neurosurgery at S.M. Kirov Military Medical Academy, also in Saint Petersburg. Dr. Ocher runs pain management clinics on the Upper East Side and in Brooklyn. Mr. Godfrey met her through a cosmetic surgeon friend.About a week before an infusion, patients come on-site for a medical exam, including an electrocardiogram, blood pressure testing and oxygen saturation. They may also meet with Devorah Kamman, a psychiatric nurse practitioner, who joined the staff three weeks ago.Nushama has no legal obligation to offer mental health care to patients, though, and a representative for Nushama originally stated that it was possible to go through their process without being seen by a mental health professional. They have since amended their policies. Ms. Kamman, the only mental health professional on staff, will now evaluate any patient who does not have their own mental health provider, they said, but will not be present while patients receive their infusions.Patients are not required to be in ongoing therapy, though, “I can’t force people to go start seeing a mental health provider or a therapist,” Dr. Radowitz said.Other clinics have more stringent requirements. “All of our patients in our clinic need to have an outpatient psychiatrist and we need a referral from them as well,” said Dr. Paul Kim, who directs a clinic at Johns Hopkins Medicine that offers esketamine.At Soundmind Center, a psychedelic healing center in Philadelphia that administers ketamine, a trained mental health professional works with every patient, throughout their experience, said Dr. Hannah McLane, the founder. “To really address their underlying problem you need to talk to them. You need to have a dedicated person that’s doing the therapy.’’James Gangemi, an integration specialist at Nushama, called the treatment “a spa day for your brain.” Victor Llorente for The New York TimesNushama’s wallpaper is filled with tiny nymphs.Victor Llorente for The New York TimesPatients can order from a menu featuring mint tea, fresh fruit and granola bars.Victor Llorente for The New York TimesNushama also has “integration specialists,” who meet with patients to discuss their intentions before an infusion session, pop in to check on how it’s going and return once it’s finished. These coaches are not licensed health professionals, though; according to Dr. Radowitz, “They’re more like sitters.”The ‘Journey’The clinic’s 18 treatment rooms are all named after psychedelic medicine pioneers, such as Ram Dass. Patients are given an eye mask and headphones to play spoken word meditations and instrumental music by Deuter, a German new age instrumentalist, that blends Eastern and Western musical elements.Each room has a leather zero-gravity lounge chair with a big red button on the armrest, to call a nurse who can stop the drip, in case of emergency. Ketamine can elevate a person’s blood pressure and heart rate, explained Dr. Iosifescu from N.Y.U., and some people experience nausea or discomfort during infusions; it also has the potential to trigger psychosis. For someone with an eating disorder, a condition Nushama says it treats, this is particularly risky because they are more likely to have cardiac issues from poor nutrition, said Dr. Iosifescu.Once the treatment is finished, an integration specialist like James Gangemi, a 32-year-old former marketer, takes over. “Afterwards you’re left with, what do I do now? How am I navigating traffic or my colleagues?” said Mr. Gangemi, who came to the profession through his own use of psychedelics. He talks with each patient about what their experience was like; sometimes he’ll do breathing exercising with them. A doctor also checks their vitals, monitoring heart rate and blood pressure.Patients are encouraged to linger, to read or journal about the experience — they can order from a menu featuring mint tea, fresh fruit and granola bars — and to have a chaperone assist them on their way home. Most stay about an hour, Dr. Radowitz said, but they are allowed to leave after a brief medical evaluation and a 15 to 20 minute meeting with the integration coach.Natalie Ginsberg, from M.A.P.S., was concerned with how short Nushama’s window for monitoring is.“In any form of psychedelic therapy, it’s really important to have time after for you to give your mind and body time to process what happened,” said Ms. Ginsberg. Esketamine clinics generally require a doctor to supervise patients for two hours, according to F.D.A. protocols.In Nushama’s “group therapy room,” there are Moon Pods to sit on and relax after a treatment.Victor Llorente for The New York TimesDr. Radowitz said that he sees “no difference whatsoever” between esketamine and ketamine, contrary to the F.D.A.’s assessments. Even so, he doesn’t think two hours is “necessary.” He acknowledges that Nushama’s practices differ from F.D.A. protocols for administering esketamine, but said he is not worried about potential risks or legal liability. “It doesn’t concern me,” he said. “I have no problem using this medication.”What’s Next?For some patients, the promise of ketamine’s benefits overshadows its risks, legal status and cost. Maria Kennedy, 30, who works in public relations, had the first of her six “journeys” at Nushama in October 2021. She had previously tried talk therapy and selective serotonin reuptake inhibitors for anxiety and depression, she said, but during the pandemic felt herself spiraling, isolated and anxious in a studio apartment. Her therapist, who knew Dr. Radowitz, referred her to Nushama.Ms. Kennedy said that during a few treatments she felt as though she were floating through space, nestled beneath the snug eye mask and hovering beyond her body. In others, the ketamine triggered precise, specific visions — once she saw her mother wrapping presents before a birthday party.By the time the I.V. was removed, Ms. Kennedy said she would feel mostly back to normal. She would stay at Nushama, taking her time to peel herself from the “cozy” chair. “The only thing that I can compare it to is waking up after a really awesome sleep,” she said. Afterward, she would take her dog to a cafe and read with a coffee or a beer.Across the country, ketamine clinics have seen increased interest. Since SoundMind opened in August 2021, they have had over 100 people a month sign up on average. Boise Ketamine Clinic in Idaho is booked until the end of April for ketamine-assisted psychotherapy treatments. In San Diego, a clinic called South Coast TMS and Ketamine had a 40-person wait-list for months, until the center raised its prices to $1,500 per session, a representative said.Dustin Robinson, a founder of the venture capital fund Iter Investments, which concentrates on the psychedelics space, estimated that a typical ketamine clinic with, say, five rooms makes $75,000 to $100,000 per month, and potentially double that if it’s fully booked. Profit margins, he added, can be more than 30 percent, which according to industry reports is far higher than most health care services. “There is not a huge amount of staff and the medicine is very cheap — almost negligible — the staff is the main cost,” he said.Mr. Robinson knows Mr. Godfrey, but is not an investor in Nushama, which charges $4,000 for six sessions; insurance rarely covers ketamine for mental health, but might if there is also a pain diagnosis. Nushama does not provide single sessions. “It’s hard to get in shape going to the gym once,” said Mr. Meloff.They also offer “group journeys,” for up to eight people in a large treatment room, which are about half the price of individual sessions, and the founders have lofty goals for attention-getting events; they hope to one day hold breath work and yoga classes on the terrace. They also say the plan is to administer MDMA or psilocybin when (and if) those psychedelics are cleared by the F.D.A.But until federal agencies approve the use of any psychedelics to treat mental health conditions, clinics like Nushama will continue to write their own rules, without regulation.“I know this movement is going to be driven by profit, but I’m really pushing people to cut their profit margins just a little bit and add more therapists,” said Dr. McLane of SoundMind. “Not having a therapist or facilitator in every room throughout is not fair to the patients.”