Jonathan Duce entered Dion's, his neighborhood liquor store in Waltham, Massachusetts, walked past the wine and six-packs and headed straight for the gummy worms. At $69 for a jar of 25, they were more expensive than the Chateauneuf du Pape, but he didn't mind. His wife likes them, he says, because they help her sleep.

The gummies aren't just candy. Each one packs a 30-milligram wallop of cannabidiol, or CBD, a constituent of the cannabis plant, more commonly known as hemp, a cousin of marijuana. Dion's started selling CBD products four months ago and now one in every 15 people who walk in buys at least one of the store's 30 CBD products, which include tinctures, vaping cartridges, smokable "flower," capsules and lotions. "But gummies are our biggest mover," says Kristen Correia, who works behind the counter.

Duce, 54, prefers rubbing salve on his neck to relieve the stress of work. "We discovered CBD at a farmer's market a few months ago," he says." Instead of taking a prescription drug, I'd rather take something like this that comes from a plant."

Mass-market retailers like CVS, Walgreens and Krogers have already signed up to carry CBD products with Walmart said to be close behind them. CBD candies and other products have been widely available online and in tens of thousands of small stores across most states; and the entrance of large retailers is about to pour gas on that fire. Big Food and Beverage lurks in the wings with its own plans to inundate the world with CBD ice cream and beer. The Brightfield Group, a market research firm, projects that CBD annual sales in the U.S., now at $600 million, will grow by a factor of 40 to $23 billion by 2023.

Hardly anyone had heard of CBD three years ago, but now two-thirds of Americans are familiar with it, according to a recent Gallup survey. One in seven Americans use it as an over-the-counter treatment for pain, anxiety and sleep problems. They have also turned to CBD for depression, muscle spasms, digestive issues and skin ailments. One in three pet owners give it to their dogs and cats, says a survey by market-research firm Packaged Facts. It's also been touted as a treatment for cancer, Alzheimer's disease and Parkinson's disease. One medical clinic reported that CBD relieved 90 percent of all symptoms in all its patients.

"Consumers are participating in one of the largest uncontrolled clinical trials in history, and no one really knows what it is they're taking," says Pal Pacher, an investigator at the National Institutes of Health and president of the International Cannabinoid Research Society. "It's scary."

Trouble is, almost all of the claims are currently unsubstantiated. Clinical trials have failed to produce convincing evidence that CBD works on anything other than rare epilepsies, the sole treatment licensed by the U.S. Food and Drug Administration. The agency, in fact, forbids companies from attributing any other health benefits to the substance. (It reprimanded Curaleaf, a startup, for making unsubstantiated claims about cancer and other diseases.)

"As far as we know, this may all be mostly a placebo effect," says Pacher. "Everybody is being sucked into the big hype."

The one thing scientists know about CBD is that it's reasonably safe. There is solid data supporting the notion that it does no harm. "There are no credible issues with toxicity, and most people tolerate it quite well," says Michael Tagen, a pharmacology researcher who consults for pharmaceutical companies about cannabis-related neuroscience.

Beyond safety, science doesn't tell us much one way or the other. But that leaves open the possibility that CBD does some good and that at least some of the claims that people make about its restorative powers are true. Many scientists, in fact, think that further testing will uncover additional benefits—but which ones, if any, remain to be seen.

Europe and Israel have gotten a big head start on CBD research due to long standing legal restrictions in the U.S., but American scientists are rushing to catch up. In the meantime, says Tagen, "People should feel free to try CBD and see if it works for them."

What's it good for?

Everyone seems to know someone who raves about what CBD has done for them. Words like "miraculous" appear frequently in media reviews. Aside from anecdotes, there is some scientific evidence that CBD has benefits beyond epilepsy. These come mainly from observational studies, which track improvements after patients take CBD. Many people show improvements with sleep, anxiety, digestive problems and a variety of aches and pains. Such studies lack the controlled comparisons to a placebo or other treatment, which is critical to getting a drug approved. But they are still considered scientific evidence, if of a weaker sort, and often establish promise for drugs long before clinical trials can confirm it.

While the animal and human observational evidence supports CBD's potential effectiveness for many conditions, the picture is far from clear. Consider CBD's impact on sleep and anxiety. A study from the University of Colorado Denver published earlier this year followed 103 patients with a mix of sleep and anxiety problems over three months of CBD treatment, finding that on average, CBD helped with anxiety, but sleep benefits faded after a month, possibly because the brain builds up a tolerance. And yet a similar patient study found the mirror opposite: that CBD gave sustained benefits on sleep but not anxiety. Rodent studies, too, go back and forth on the same questions.

This sort of hit-or-miss evidence has also been turning up for CBD's ability to fight the "inflammation" caused when the body's immune system attacks healthy cells. Inflammation is considered a cause or symptom of a wide range of ailments, including allergies, heart disease and illnesses of the gut. "Most major diseases are inflammatory, and that alone would make CBD useful," says Maurizio Bifulco, a professor and CBD researcher at the University of Naples Federico II Medical School in Italy.

Likewise, research indicates that CBD may—or may not—be helpful for psychosis, opioid withdrawal, arthritis, antibiotic-resistant infections, non-Parkinson's tremors, Alzheimer's disease, multiple sclerosis, tissue rejection after transplants, the side effects of cancer chemotherapy and even for several types of cancer itself, including the most aggressive and untreatable form of brain cancer. (Oddly enough, the property that wins CBD the most praise from users—pain relief—is one of the most weakly supported, with CBD often failing to provide much benefit in studies.)

Scientists are not deterred by this conflicting data. Many new drugs get mixed results in tests—even Tylenol, a proven pain reliever for millions of people, comes up short in some trials. The clinical trials on CBD that have been done so far could have been flawed in ways that missed some of its healing properties. Hundreds of new trials now getting underway may do a better job of zeroing in them. "We really don't know what to measure in patients right now," Pacher says. "I do think in the longer term we'll figure that out and see some positive results in clinical trials."

What impresses researchers most about CBD is that it offers at least a hint of effectiveness against such a wide range of often serious and hard-to-treat conditions without providing a corresponding hint of the problematic and sometimes dangerous side effects that hang over virtually all other drugs. Of those who use CBD oil, 40 percent take it daily, according to Paul Norman, CEO of Heavenly Rx, a major producer of CBD products. A survey by Consumer Reports earlier this year that found 22 percent of CBD users are using it as a substitute for prescription medications.

Industry Rushes In

A more relaxed regulatory environment has helped set the stage for the CBD boom. Although the hemp plant includes only trace amounts of THC, it is a close cousin to marijuana. (CBD can also come from marijuana plants in which the THC has been bred out or extracted.) While there are still occasional stories of CBD busts and seizures at hemp farms, mom-and-pop stores and airports, they are rapidly vanishing. That's due to public outrage over any effort to suppress what's increasingly seen as a beneficial and harmless substance and to federal and state efforts to spell out CBD's legality. It helped, too, that the 2018 Farm Bill passed by Congress protected hemp growers, processors and sellers from federal or state prosecution, with reasonable qualifications such as keeping THC levels below 0.3 percent of the dry weight of the product. "There are still FDA restrictions," notes Brandon Beatty, CEO of Bluebird Botanicals, one of the better-known purveyors of CBD, with 2018 sales of $14 million. "But at least there's no risk now from the Drug Enforcement Administration."

With consumers going all in and the government backing off, the business world has stepped up to meet demand. Bluebird's 2018 sales were more than double its 2017 figures and the company says it's on track to more than double sales this year, too. That's typical for the industry. Veritas Farms, another major player and a publicly traded company, has also doubled revenues annually for the last two years and turned in first-quarter revenues this year of more than $1.5 million, nearly four times higher than the same quarter last year.

Big retail's entry will keep that streak going. Veritas is already in 950 stories, including CVS and Rite Aid, and expects to reach 1,350 stores this year across 22 states as Kroger starts hawking the company's products. Heavenly Rx, another major player, brought in CEO Norman from Kellogg, where he ran the company's $9 billion North American business. "The CBD industry's future is in mainstream distribution," says Norman, adding that he thinks as much as two-thirds of all CBD products will be sold in big stores by 2022.

The boom will be even bigger when CBD starts getting infused into major consumer products, such as cosmetics. Most of the stuff is currently sold as tinctures and capsules, but consumers have also taken to slathering it on their skin. Most of the leading CBD manufacturers have started selling a range of lotions and balms and major cosmetics retailer Sephora has taken on topical CBD products from Estée Lauder and other companies.

Soon consumers may be getting CBD with almost anything they put in their mouths. "Global food, beverage and tobacco companies are just treading water waiting for the FDA to allow them to add CBD," says Brady Cobb, CEO of SOL Global Investments, a cannabis-focused investment firm that owns 45 percent of Heavenly Rx. "When that happens, they're going to plunge in head first." Among the companies that have reportedly already made plans to bring out CBD-infused products are Coca-Cola, Molson Coors Brewing and American Premium Water. Heavenly Rx has invested in craft soda maker Jones Soda, with the intention of eventually bringing out CBD versions. It's also acquired a line of protein bars for the same reason. "CBD can help with recovery after a yoga workout," explains Norman—a claim many users would endorse, though no study has clearly proven that CBD aids in workout recovery.

What's in the bottle?

With CBD products, it's hard to be sure what you're getting. THC aside, most companies boast of offering "broad spectrum" or "full spectrum" CBD products, which means other ingredients from hemp plants end up in the mix besides CBD. There are in fact hundreds of compounds in hemp falling into a variety of categories with names like cannabinoids, terpenes and flavonoids.

Many consumers are already sold on the notion of "the entourage effect"—the scientifically unsubstantiated, though not entirely implausible, claim that the different ingredients somehow combine to provide health benefits that go beyond what any of the individual components might do. But good luck sorting out which of those ingredients are actually present in a given CBD product and in what quantities. "'Full spectrum' is a meaningless marketing term," says Tagen. "It's rare that any of these companies actually test for these ingredients and even rarer that they release the results."

In fact, it's hard for consumers to know much of anything about what they might be getting when they buy a CBD product. "Some of these companies have zero science behind what they're doing," says Karyemaître Aliffe a Seattle-based physician and pharmaceutical researcher who runs a small biotech company and teaches at the University of Miami Medical School. "The quality control and regulatory oversight for CBD is not much beyond what it is for Snickers bars."

Studies have indicated CBD products from some established vendors can have CBD levels well below or above what's claimed on the label, along with illegally high levels of THC and contaminants including heavy metals and pesticides. The hemp plant tends to pull in whatever lies in the soil and hang onto it, so unless the soil or resulting products are carefully tested—still not the case for many CBD products, especially those imported into the U.S. rather than grown and produced here—there may be risks for any number of toxins.

For what it's worth, vendors like Bluebird, Veritas and Heavenly Rx insist they have rigorous quality-control and testing programs in place and enlist independent firms to analyze and certify their products.

But even if you knew exactly what is in the bottle, is there enough of it to do you any good? There's little understanding of CBD dosages at this point, but what scientists do know suggests the amounts normally advertised as a typical dose are probably well below what's needed to make a big dent in a health problem. The rare childhood epilepsies—the one condition considered proven to be treatable with CBD—are treated with daily doses in the range of 500 milligrams, or about a sixtieth of an ounce—and that's for children. The standard recommended adult dose of over-the-counter CBD oil is an eyedropper-full, typically amounting to between a fiftieth and a hundredth as much CBD as the child-epilepsy dose. It wouldn't be advisable to take hundreds of milligrams a day—that would require chugging a whole bottle—outside of a doctor's care, but anyone who did would likely be paying more than a thousand dollars a month for the habit.

Cecilia Hillard, director of the Neuroscience Research Center of the Medical College of Wisconsin, and one of the U.S.'s more prominent CBD researchers, says that she's encountered people who actually take such large over-the-counter doses and who do in fact report higher levels of relief from such problems as neuropathic pain. But one big hitch, notes Hillard, is that at doses that large, many CBD products would be delivering enough THC along with it to provide a bit of a high and that's more likely where the relief is coming from. "Even at high doses, the effects of CBD itself tend to be mild," she says. Human studies of CBD using purified and tested versions of CBD with little or no THC have shown effectiveness against acute anxiety, but they use single doses in the range of 300 milligrams—dozens of times larger than what a typical consumer takes. If CBD vendors were to recommend such high doses, it would raise concerns about as-yet-undiscovered side effects. And it prices CBD treatment out of the reach of most consumers.

Tongue vs gut vs clinical trials

Adding to the uncertainties over CBD's effectiveness is the variation in how it gets into the bloodstream, which is where it has to go to do any good. Smoking and vaping are relatively efficient ways to take it—they deliver about half of the CBD in a dose to the bloodstream in seconds. But they carry health risks similar to smoking and vaping tobacco. Placing a tincture under the tongue and holding it there for a minute delivers about 20 percent of the CBD, with a delay of a few minutes. Swallowing CBD is the least efficient of all—only 10 percent makes it into the bloodstream because liver enzymes break CBD down in the gut—and what does make it through can take two hours to reach your blood. Eating fatty foods helps, because CBD dissolves in fat and is thus more easily absorbed in the gut before being broken down. But that doesn't bode well for consumption via fat-free beer or soda. "You'd end up with vanishingly small amounts in your body," says Hillard. "I can't imagine that little doing anything at all."

That makes taking CBD under the tongue—so-called sublingual consumption—a winner in many experts' and aficionados' minds. But you won't see that recommended on your bottle of CBD oil. That's partly because many consumers don't like the oily, grassy-tasting stuff pooling around their mouths. It's also because the FDA doesn't allow unapproved references to sublingual dosing, considering it a drug-delivery mechanism. "Under the tongue is my personal preference," says Alexander Salgado, CEO of Veritas Farms, "but I can't say that on a label until the FDA provides some clarity." If the FDA relents on that score, Salgado predicts there'll be a big market for CBD-saturated strips that dissolve under the tongue.

Chewing gum could hit another sweet-spot. Axim Biotechnologies, which has patents on gum-based drug delivery and FDA approval, is selling gum with 10 milligrams of CBD. "A chemotherapy patient can chew a piece and get immediate relief," claims Axim CEO John Huemoeller. The company will soon introduce a line of mass-market "wellness" gums that mix CBD with caffeine, ginseng, melatonin, tryptophan (the ingredient in turkey that supposedly makes everyone sleepy after Thanksgiving dinner) and other ingredients. It's also starting clinical trials of toothpaste and mouthwash that will aim CBD's claimed anti-bacterial and anti-inflammatory properties against gingivitis and periodontitis.

Researchers are now fashioning clinical trials to learn which patients can be helped by what form of CBD. More than 500 trials are in the works around the world, says Hillard, fueled partly by startups already profiting from CBD. One firm, Kannalife Sciences, is designing clinical trials for treating chemotherapy side effects, liver disease, chronic skin conditions, non-Parkinson's tremors and even stage IV cancers. "At stage IV you have to hit the cancer with a sledgehammer," says CEO Dean Petkanas. "We want to transfuse 10,000 milligrams of CBD into bone marrow to see if it reduces the proliferation of cancer cells."

Researchers will have to ply the scientific method through hype-roiled waters for years. In the meantime, doctors, scientists and consumers will have to feel their way. "Cannabinoid therapeutics is a completely new frontier," says Petkanas. "We're just where antibiotics were in the 1930s."