We're in the midst of a CBD craze.

Cannabidiol — CBD — is a compound in the marijuana plant with purported medical benefits but very little (0.3 percent or less) THC, the plant’s psychoactive ingredient.

In other words, it won't make you feel high or stoned.

Dozens of online companies sell it as a supplement. And it can be found in everything from cosmetics to bottled water to coffee. You can pick it up it in health food stores and smoke shops — even in New Jersey, where pot hasn't been legalized.

The most common reason for using CBD oil is to alleviate anxiety and depression, said Martin A. Lee, director of the non-profit cannabis research group Project CBD and author of "Smoke Signals: A Social History of Marijuana."

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It’s also popular for pain and is being used to treat cancer, Crohn’s, diabetes, rheumatoid arthritis, PTSD, cardiovascular disease, antibiotic-resistant infections, multiple sclerosis and schizophrenia.

Because marijuana is illegal at the federal level, there's a dearth of clinical trials on the medical effects of CBD oil in the U.S., but Lee said there is “extensive pre-clinical research” here and more definitive studies abroad. It's approved for chronic pain in more than two dozen countries, he said.

Recently, the drug Epidiolex, whose active ingredient is CBD oil, was approved by the FDA for use in controlling seizures in children.

But is it legal?

Despite its widespread use, the short answer is no, CBD oil is not legal.

That’s because the oil comes from the marijuana plant, which is classified by the federal Drug Enforcement Administration as a substance with “no currently accepted medical use and a high potential for abuse,” requiring strict control, Lee said.

Of course, the legality of pot in the U.S is a tangled web. Even in states like California and Colorado, where marijuana is legal on the state level, dispensaries could technically be shut down at any time by the federal government.

Similarly, though CBD oil is technically illegal on the federal level, it is sold freely online and in stores even here in New Jersey. Erica McBride, executive director of the National Hemp Association in Washington, said there have been instances in states where pot hasn't been legalized where CBD oil was confiscated at the post office or people possessing it were arrested, but it's “very rare.”

Hemp is marijuana grown for non-recreational uses and contains 0.3 percent or less of THC.

“To my knowledge, everyone who fought these incidents won, once they proved the CBD oil had 0.3 percent or less of THC,” she said.

Growing and producing CBD oil made from hemp may soon become fully legal. Lawmakers are working to finalize a 2018 Farm Bill sponsored by Sen. Mitch McConnell that removes hemp from the controlled substances list, allowing it to be grown legally on a large scale. Negotiators are hoping for a completed report this month and a vote on the bill by year's end.

Even then, it remains to be seen what the FDA will do to regulate CBD oil products.

"It's very complicated and messy and uncertain," McBride said.

Is it safe?

In its pure form, CBD oil is non-toxic, even at large doses, and has no abuse potential, experts say.

Unfortunately, the legal murkiness of CBD oil means that in states like New Jersey, no one is regulating its safety, efficacy or labeling. CBD oil cannot be shipped here from California or Colorado.

Buying CBD oil in New Jersey is “like the Wild West,” said Tristan Quintan of Montclair's Inner Eye, a smoke shop on Bloomfield Avenue. Short of sending it to a lab yourself, there’s no way to be certain what’s in a product.

Compounding the danger is that people who are sick are vulnerable to the allure of CBD oil. "It is very disturbing that people who are ailing reach for these products and there are no safety controls," Lee said.

Contamination by pesticides, herbicides and solvents used in the extraction process is a big concern. The term "organic" is meaningless, McBride said, since CBD oil is not eligible for FDA organic certification.

The lack of oversight means products may contain only synthetic CBD, or little or no CBD oil at all. A study last year in the Journal of the American Medical Association measured the amount of CBD oil in 84 products from 31 companies and concluded that 26 percent contained less CBD than advertised.

Mislabeling the amount of THC in a product, which the researchers also found, could cause problems, especially in children.

So what to do? McBride and Lee recommend shopping by brand — finding a reputable company by looking up online reviews or asking a retailer you trust.

Such companies will post test results from labs unaffiliated with the company; even if they are inscrutable, it’s one sign of transparency.

Or you can ask a company for lab reports. "If they are reluctant to share these results with you, it should be an automatic red flag," McBride said.

CBD products from U.S. companies are safer than those from overseas, especially those produced in countries like China and Romania, where soil may be contaminated with pollutants such as lead and mercury.

"Most companies using domestic hemp advertise that fact on their websites," McBride said.

Try to find out if the CBD oil is extracted using CO2 rather than toxic solvents like BHO, propane, hexane or other hydrocarbons.

Vaping requires extra vetting, since vape oil cartridges generally contain additives such as propylene glycol, which, when heated, produces the carcinogen formaldehyde. Never use flavored vape oil, especially cream and cinnamon, which are toxic when heated and inhaled.

What's the best way to use CBD oil?

The only way to find the right dose of CBD oil is trial and error. Companies can’t give guidelines, since that would be making a medical claim, McBride said.

When starting out, take a few very small doses over the course of a day and stick with that for a few days, Lee said, observing and making small adjustments. "Don’t get impatient and overdo it," he added. Large doses are sedating. And, although it’s counterintuitive, he said lower doses are often more effective than higher ones.

The method used to take the oil also makes a difference.

Vaping is the quickest-acting, but it also fades fastest (in about 20 minutes), making it the usual method for pain flare-ups or the onset of a panic attack. Placing the oil under the tongue takes about 20 minutes to kick in, but effects can last for several hours.

The ratio of THC to CBD in a product is also important. Lee said products made with CBD oil extracted from resin-rich marijuana plants rather than industrial hemp, which may have no THC at all, are more therapeutic because the two ingredients work synergistically. These oils are also purer, since fewer plants are used and less refining is necessary. However, these products are available only in states with legal weed.

As if there were not enough confusion, Quintan, of the Inner Eye, said different strains of the cannabis plant are used to make CBD oils with widely differing effects. A strain named the Pineapple Express will make you feel euphoric, he said, while Blueberry OG helps insomnia.

What you won't feel is high. Whether that's a plus or a downside is for you to decide.

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