Cannabidiol, or CBD, a nonintoxicating component of the marijuana plant, is touted as a magic bullet that eases pain, anxiety, insomnia and depression. Salves, sprays, tinctures and oils containing CBD are marketed as aphrodisiacs; as balms for eczema, pimples and hot flashes; and even as treatments for diabetes and multiple sclerosis.

Unlike THC, or tetrahydrocannabinol, the “psychoactive” component of the cannabis plant, CBD won’t get you “high.” But scientists know little about what it can do: Most of the information about CBD’s effects in humans is anecdotal or extrapolated from animal studies, and few rigorous trials have been conducted.

“It is a kind of a new snake oil in the sense that there are a lot of claims and not so much evidence,” said Dr. Dustin Lee, an assistant professor in psychiatry and behavioral sciences at Johns Hopkins University who is planning a human trial of CBD for use in quitting smoking.

The Food and Drug Administration has approved drugs made from synthetic substances similar to THC to treat poor appetite and nausea in people with AIDS or cancer. But the FDA has approved only one drug containing CBD, Epidiolex, after clinical trials found it reduced seizures in children with rare, severe forms of epilepsy.

“There’s a lot of hype about everything about CBD,” said Dr. Orrin Devinsky, director of the NYU Langone Comprehensive Epilepsy Center, who led the Epidiolex studies and went out of his way to say the drug’s effect was “not miraculous.” “There is certainly data that it has a variety of anti-inflammatory effects, but whether that translates into improving human health is unknown. Does it help people with eczema, rheumatoid arthritis or ulcerative colitis? We don’t know. There is a good theoretical basis, but the studies have not been done.”

The FDA still considers CBD a drug, so it cannot be sold in foods or drinks or as a dietary supplement, and several states and cities — including New York City, California, Maine and Ohio — have ordered restaurants to remove CBD from lattes, smoothies, muffins and other foods or face fines. The FDA has issued warnings to companies that claim CBD will treat or prevent disease, saying such claims could dissuade seriously ill patients from seeking appropriate therapies.

Dr. Yasmin Hurd, director of the Addiction Institute at Mount Sinai in New York City and a professor at the Icahn School of Medicine who has done extensive research on CBD, says the compound holds particular potential for the opioid crisis because it appears to reduce heroin cravings in recovering addicts. But “let’s do the research,” she said. “It’s crazy that this substance is being consumed by everybody, yet we still don’t know the mechanism of action.”

CBD has a relatively good safety profile and is “hands-down safer generally than THC,” Hurd said. But it can cause adverse side effects, including sleepiness and diarrhea.

First isolated in 1940, CBD is one of more than 100 biologically active components called cannabinoids that are in the cannabis plant. Scientists have long known CBD has anti-convulsant and anti-inflammatory effects, but it was not until recent years that CBD got more serious attention from researchers, who initially were more interested in studying cannabis’ psychogenic components, like THC.

“You don’t get a high from CBD no matter how much you take,” said Sumner Burstein, an emeritus professor of biochemistry and molecular pharmacology at the University of Massachusetts Medical School. It is also not addictive, but there is a possibility CBD will interact poorly or interfere with other medications, he said.

Studies are getting underway to evaluate whether CBD can alleviate anxiety or post-traumatic stress disorder, or help with substance abuse and tobacco cessation. Leaf Vertical, a biopharmaceutical research company, will explore whether it can enhance cancer therapies. Animal studies suggest its anti-inflammatory effects may have benefits for helping to manage chronic pain or treat arthritis or inflammatory bowel diseases like Crohn’s disease. It is also being looked at for the treatment of autism.

GW Pharmaceuticals, which makes Epidiolex, has a multiple sclerosis drug approved in Britain that combines CBD and THC. The company is exploring the combination for other therapeutic applications, and is studying other uses for CBD alone, including for Rett syndrome, a rare genetic disorder that has devastating neurologic consequences in young children.

The combination of CBD and THC may be more effective for some conditions than CBD alone, experts say. While cannabis has shown promise for treating pain syndromes, for example, it is not clear that CBD alone will be an effective pain reliever.

Some research has reported promising results in psychiatric applications. Last year, European scientists reported that patients with schizophrenia who were given 1,000 milligrams of CBD in addition to their regular antipsychotic medications experienced fewer hallucinations and racing thoughts compared with those on a placebo. But other studies of schizophrenia have not found the same benefits.

Scientists are anticipating easier access to the drug for research since a bill signed late last year removed hemp-derived products like CBD from the list of Schedule 1 controlled substances, and allowed for the cultivation of hemp, which is defined as having less than 0.3 percent THC content. Before passage of that bill, CBD was considered part of the marijuana plant, and researchers in the United States were required to have a license to possess it and had to obtain the product from a government-approved source and keep it under lock and key.

Still, procuring high-quality, uncontaminated CBD for research remains a daunting task, said Lee, of Johns Hopkins.

“It might be available at the local 7-Eleven in Pennsylvania,” Lee said, “but any product you get on the market is not federally regulated by the FDA, so the purity and safety and quality are questionable.”

Indeed, a recent study that evaluated dozens of CBD products ordered online found that nearly 70 percent were not labeled accurately and had either higher or lower concentrations of the ingredient than indicated on the label. Some also contained THC.

Hurd, who has been studying CBD for nearly 10 years, warns that the expectations around the substance are unrealistic. “People are making it out to be a nirvana kind of drug, and that’s a problem,” she said. “One compound cannot cure everything.”

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