If you only know three letters associated with cannabis, they're probably T-H-C. But there's another term on the rise: CBD.

CBD, one of the more than 100 chemicals in cannabis, is emerging as a popular wellness ingredient. The plant extract, often consumed as an oil under the tongue, is now the featured ingredient in high-end products including coconut oil, body lotion, face serum, olive oil, jam, bath scrub, cold-brew coffee, sports salve, lip balm, infused water, gummy snacks and dog treats. Products' prices vary but may cost about triple what their CBD-less counterparts do.

Unlike THC (Tetrahydrocannabinol), CBD (Cannabidiol) won't get you high, and it's becoming so mainstream that even Coca-Cola may have interest in a CBD drink.

What is CBD?

CBD is a non-psychoactive chemical compound – meaning it won't alter a person's mental state – that can come from two different cannabis plants: The hemp plant (with less than 0.3 percent THC present) or marijuana plant (where there's much more psychoactive THC). CBD products tend to be derived from hemp.

There are still plenty of unknowns when it comes to CBD. The FDA has only approved the use of CBD oil in specific cases of epilepsy. Epidiolex, the FDA-approved CBD drug, was placed in the "least restrictive" category of controlled substances by the Drug Enforcement Agency, meaning it's in the same category with cough medicine Robitussin AC.

More:FDA approves first marijuana-based epilepsy drug: CBD oil

Laws surrounding the sale of hemp CBD are murky at best; products made with the cannabinoid are not legal in all 50 states, though the oil is legal in more states than medicinal marijuana.

Even in California, where recreational marijuana consumption is legal for adults 21 and older, there are complicated rules. And yet, even with new guidance on CBD use in food products in the state, the industry continues to grow.

“A lot of states only allow CBD for a limited amount of medical conditions. But they’re not checking the mail, not checking these other companies that are shipping in,” Kristen Yoder, host of podcast CannaBS Detector, said at the first-ever CBD Expo in Anaheim, California. “People are gonna push the envelope until they get in trouble.”

The appeal and drawbacks of CBD

The FDA has approved of the use of CBD to treat Lennox-Gastaut syndrome and Dravet syndrome, two forms of epilepsy. So what's the draw of the chemical compound for everyone else?

Pro skateboarder Matt Miller, who started CBD brand Miller Healer, turns to CBD sports salve and patches as his primary medicine. Stacy Verbiest, who founded therapeutic women’s cannabis line Wink with creams and tinctures, says CBD helped her friend manage the pain of cancer treatments. Pet owners buy cat and dog treats with the hopes of helping their best friend feel happier and more comfortable.

Experts, including those with the World Health Organization, note that there's some potential for treatment beyond epilepsy, but research isn't as advanced.

Greg Avetisyan is co-founder of the CBD store Topikal Everything Hemp, which just opened a second California location this year. "Though not medically proven, CBD’s main purpose is to help alleviate inflammation," he said. "So when people use CBD by itself, they're getting the medicinal benefits of the plant without the psychoactive effects. It treats a lot of different anxieties and pains."

THC, meanwhile, helps with "pain relief, sleep and opening up the appetite," Avetisyan says. He and his brother opened Topikal because they prefer treating their conditions – he has rheumatoid arthritis and his brother has anxiety – with just CBD. For them, THC induces paranoia.

Dr. Leeta Jussila, a practitioner of Oriental medicine who specializes in cannabis, says that everyone's system is different, so the way people absorb CBD differs. She recommends new users consult with health care providers and closely track how small doses of the chemical effect them.

"They could get a headache. Sometimes people say, 'I feel funny,' but you’ll never overdose on cannabis. You'll just start to detox," she said. "CBD is an oil, fat, lipid. Some people might get diarrhea. I’ve had one person get nausea, dry mouth or dizziness. But it depends on the quality of the product."

An industry on the rise

Marijuana research firm Greenwave Advisors anticipates that the CBD industry could reach $3 billion by 2021 and eventually well over $200 billion in the U.S., if the so-called Farm Bill legalizing hemp as a crop passes.

Jonathan Eppers, creator of a CBD beverage company, sees the plant supplement as good for his well-being and good for business. CBD “gave me a purpose again in my life,” he said.

After going through “debilitating anxiety” while stepping down as CEO from embattled rental housing startup RadPad about two years ago, he turned to CBD oil on the recommendation of a friend. He was wary of buying a product from a natural food store that, at the time, was kept in a locked box.

However, "in three days, I just felt calmer."

Excited to introduce others to CBD, Eppers watched market trends, talked to hemp farmers and decided to launch a brand-new company featuring his favorite chemical, drink brand Vybes.

The California-based hemp CBD beverage went on the market this January. Eppers projects Vybes will produce 1-1.5 million bottles this year and already has hundreds of retailers selling drinks across the country.

As Eppers has seen, the CBD foods market is quickly growing.

More:Coca-Cola: We're 'closely watching' the market for drinks infused with cannabis extract

As for Coca-Cola's possible CBD drink? “Along with many others in the beverage industry, we are closely watching the growth of non-psychoactive CBD as an ingredient in functional wellness beverages around the world,” the company said in a statement in September. “The space is evolving quickly. No decisions have been made at this time.”