Let’s see what the research says before pouring it into our tea and rubbing it all over our bodies.
Dr. Friedman is a psychiatrist and a contributing opinion writer.
Credit Ronen Tivony/NurPhoto, via Getty Images
Suddenly, CBD is everywhere. CBD, short for cannabidiol, a non-psychotropic component of cannabis and hemp, is being promoted as the latest miracle cure. Enthusiasts rave about its supposed anti-anxiety, anti-inflammatory, antidepressant and, well, anti-everything-you-don’t-like effects.
From pills to edibles, CBD is wildly popular, and it is easily available online and in stores. Indeed, sales are predicted to reach $22 billion by 2022, according to the Brightfield Group, a cannabis market research firm.
I first encountered CBD while on sabbatical a few years back. As I droveup the Oregon Coast Highway, it was hard to miss all the cannabis shops along the Pacific. I stopped in one, perused the menu, and selected two marijuana specials — Nine-Pound Hammer and Trainwreck — and some CBD gummy bears. The cannabis was, well, as advertised, and the CBD candy, as far as I could tell, was a fruit-flavored placebo.
Many of my patients have tried it or want to learn more about it. One of them, an educated, successful and anxious man in his 40s, recently told me he triedmixingCBD oil in his tea, but it didn’t make him calmer. Then he rubbed the oil on his injured knee, and pronounced it a magic cure.
Which invites the critical question: Just how effective is CBD, and for what kinds of ills?
Cannabidiol has little direct effect on the cannabinoid receptors in the brain, so it is largely devoid of the euphoric effects of THC, the major intoxicant in marijuana. But if CBD really had no psychotropic effect at all, it would be hard to understand its popularity. In fact, because it alters the brain’s serotonin receptors and may interfere with the breakdown of anandamide — a cannabidoid that is produced naturally in the brain — it could well affect feeling and thinking.
But what does the evidence show?
In 2017, the National Academies of Sciences, Engineering and Medicine convened a panel of experts to review the health effects of cannabis and cannabinoids. They examined more than 10,000 studies, most of which examined marijuana, not CBD. They found evidence that some cannabinoids — not including CBD — are effective for pain, nausea from chemotherapy and muscle spasms in multiple sclerosis.
When it comes to CBD, the panel found only a few small randomized clinical trials, and concluded that there was insufficient evidence that CBD was effective in treating conditions like insomnia, addiction to cigarettes and Parkinson’s disease, and limited evidence in its ability to treat anxiety.
This year, the Food and Drug Administration approved Epidiolex, a CBD concentrate, for two rare and severe forms of epilepsy, on the basis of several clinical trials.
To be fair, the paucity of data about CBD’s efficacy and safety in part reflects the federal government’s irrational restrictions on cannabis research. Because cannabis is classified as a Schedule 1 drug, you need a license from the Drug Enforcement Administration to research it and, until two years ago, you could use only the cannabis grown at the University of Mississippi.
The good news is that in 2017, the National Institutes of Health funded cannabinoid research to the tune of $140 million, including $15 million on CBD. The F.D.A. also loosened restrictions on CBD research in 2015 and has announced that it is considering “pathways” to allow the sale across state lines of CBD in food and beverages, sales now confined to states that have approved CBD use.
Still, the explosive popularity of CBD is way ahead of any evidence to support its efficacy — or reliable reassurances that it has no serious adverse effects. Where is the healthy skepticism when we need it?
The public, rightly, is quick to demand proof of safety and efficacy when it comes to synthetic pharmaceuticals. Why should natural products, like CBD, get a pass?
Perhaps it’s because many people have romantic and misplaced notions about nature. Some even point out that we come hard-wired with cannabinoid receptors in our brains and they must have a purpose, so why not use them? This is not exactly a persuasive argument: Nature endowed us with our own cannabinoids, so unless you have a deficiency of them or sluggish receptors, you really don’t need supplementation.
Consumers who are still keen on the idea of CBD might want to know exactly what they are getting for their money — considering that the manufacturing of CBD products is completely unregulated.
Here, the evidence is not going to make them happy. A 2017 study in JAMA reported that only 26 of 84 samples of CBD oils, tinctures and liquids purchased online contained the amount of CBD claimed on their labels. Eighteen of them contained THC, which could lead to intoxication or impairment in some individuals. And a quarter had less CBD than advertised. The F.D.A. has likewise found many products that did not contain the amount of CBD they were claiming.
Future studies may show otherwise, but at present CBD looks more like an expensive placebo than a panacea.
Richard A. Friedman is a professor of clinical psychiatry and the director of the psychopharmacology clinic at the Weill Cornell Medical College, and a contributing opinion writer. A version of this article appears in print on Dec. 26, 2018, on Page A19 of the New York edition with the headline: Is CBD Helpful, Or Hype?. Order Reprints | Today’s Paper | Subscribe