The once squeaky-clean image of former teen Disney star Miley Cyrus took another hit – so to speak – this weekend, when a video emerged of her purportedly smoking a bong filled with salvia.

While her father Billy Ray Cyrus is said to be saddened by the video, which appears on the celebrity gossip website, plenty of others are asking: what is salvia and is it legal?

Turns out the hallucinogen -- officially called Salvia divinorum -- is legal in the state of California where Cyrus apparently used it, though it's illegal in 12 other U.S. states. It's also illegal in Canada, although it is openly marketed by some "head shops" in Canada.

Dr. Bryan Roth, a professor of pharmacology at the University of North Carolina explains that the drug is an intense hallucinogenic that's fairly new on the drug scene. He says in the late '90s, recreational drug growers learned how to add the purified active ingredient, salvinorum A, to plants.

"It's only in the last four or five years that it has taken off as a fad," he told CTV's Canada AM from Chapel Hill, N.C.

Yet while its popularity is new, the hallucinogen, with is part of the sage and mint families, has been used for centuries by shamans in Mexico for spiritual healing. In fact, the name salvia means "to heal" and divinorum means "divination." The drug is also known as "diviner's sage" and "magic mint." 

What makes salvia so popular is that it gives an intense high that takes just a few seconds to kick in and that lasts only a few minutes.

"Most people describe the effects as nearly instantaneous," Roth explained. "They're basically disassociated from normal reality. The effects of that can range from hilarious laughter, like you see with Miley Cyrus, to stark terror. Then within five to 15 minutes, the effects abate. And within half an hour, people are back to normal."

While research on the drug is scant, a U.S. government-funded study was released just last week in the journal Drug and Alcohol Dependence. In the study, researchers from the Johns Hopkins School of Medicine tested the drug on four subjects with prior experience with hallucinogens.

Two users rated the strength of the effect as "as strong as imaginable" -- considered unusual for people with prior experience with hallucinogens.

The subjects also reported the drug's effects were different from those caused by LSD or "magic mushrooms." While those drugs leave users high but still aware of the world around them, the salvia users said they felt as if they had completely left reality, gone to "other worlds or dimensions," had "contact with entities," and experienced "mystical-type" effects, the researchers reported.

But it is when user lose touch with reality that the drug can become very dangerous. Burnaby, B.C. woman Cassie Walde says she unknowingly jumped out of a third storey window after smoking the plant extract.

"I'm lucky to be alive," she told CTV B.C. "I had a high. It was really intense -- really confusing -- and I woke up outside on the pavement three stories down screaming."

Walde now has scars where surgeons reconstructed her shattered jawbone and where a breathing tube had to be inserted. She is still missing many of her teeth.

There were no physical effects of the drug itself, the researchers found: no significant heart rate or blood pressure changes, no tremors or other side effects. And animal studies indicate the drug is not addictive.

Still, Roth points out, because salvia is not well studied yet, the long-term effects on the brain are unknown.

Here in Canada, the popularity of the drug is said to be growing. According to the 2009 Canadian Alcohol and Drug Use Monitoring Survey, about 1.6 per cent of Canadians aged 15 or older have tried salvia. For those aged 15-24, the number rises to 7.3 per cent.

Products containing salvia divinorum or its active ingredient, salvinorin A, are considered natural health products and, must be authorized by Health Canada in order to be sold. Since Health Canada has not licensed any product containing salvia, sales are illegal.

Health Canada is still reviewing whether salvia should be included in the Controlled Drugs and Substances Act, which bans other hallucinogens, such as peyote, magic mushrooms and LSD.