The US Food and Drug Administration has approved a new depression drug, esketamine, for patients who have not responded to other antidepressants. The treatment, a nasal spray related to the party drug ketamine, will be the first fast-acting depression drug on the market.

Unlike most older antidepressants, esketamine (which will be marketed as Spravato) lifts patients’ moods within hours where other antidepressants available now can take weeks, if they work at all. The drug, developed by Johnson & Johnson’s Janssen subsidiary, is intended to be used with another antidepressant, and only by people who have already tried two and don’t feel better.

Part of the excitement around esketamine comes from the fact that it works differently from traditional antidepressants like Prozac. Prozac, originally marketed by Eli Lilly and approved in 1987, makes a chemical called serotonin more available in the brain, easing depression symptoms for some patients. Esketamine, on the other hand, targets a different chemical, called glutamate. It blocks a glutamate receptor, causing changes in the brain — a method that has increasingly been investigated as an alternative way to treat depression.

Over the last decade, as small studies suggested that ketamine might help people who are depressed quickly feel better, clinics promising ketamine treatment for depression have popped up around the US. These promise fast relief, but are largely unregulated, stray from accepted research, and are not covered by insurance.

The FDA approval specifically states that the drug will only be available in certified clinics where doctors can monitor the patient, a move that is intended to significantly lower the risk of abuse. The treatment still won’t be cheap: it can cost almost $900 per session, which would bring a monthly cost, at the recommended two sessions a week, to nearly $7,000, according to Stat News. However, with the FDA approval, it is likely that esketamine treatments will be covered by insurance and that it will have fewer side effects than ketamine, which can cause nausea, vomiting, and drowsiness.

Still, esketamine will also carry the FDA’s gravest warning — a black box that says there’s potential for this drug to be abused. The boxed warning also indicates the drug may cause suicidal thoughts.

Doctors have been split on the FDA’s approval of the drug, which was previously fast-tracked and designated as a breakthrough therapy. Though some are eager for a new treatment in a field without much movement, others expressed concern that enough safeguards would be put in place for the drug to be administered responsibly. “I have no doubt in my mind that this is a very useful treatment,” Gerard Sanacora, a psychiatrist and the director of the Yale Depression Research Program told Stat News, who added that the benefits have “to be balanced with how do we use this rationally and in what step in care do we use this medicine.”

Erick Turner, a former FDA reviewer and an associate professor of psychiatry at Oregon Health & Science University struck a balanced view of the promises of the new treatment. “Thank goodness we now have something with a different mechanism of action than previous antidepressants,” he told the New York Times. “But I’m skeptical of the hype, because in this world it’s like Lucy holding the football for Charlie Brown: Each time we get our hopes up, the football gets pulled away.”