Videos of teen star Miley Cyrus (aka Hannah Montana) tripping on salvia may have anti-drug campaigners and moral entrepreneurs all atwitter, but the drug itself poses little short term danger, according to the first close study to examine the substance. The stuff is powerfully hallucinogenic, the study found, but does not produce adverse health effects in healthy people in the short term.

In the study, which was funded by the National Institutes of Health, researchers at Johns Hopkins School of Medicine in Baltimore gave salvinorum A to four physically and mentally healthy paid subjects. The subjects reclined in chairs and smoked under clinical observation over 20 sessions and at increasing dosage levels.

The study found that salvia can be intense and disorienting, but that its effects were short-lived (peaking at about two minutes after ingestion and dissipating by the 20-minute mark). Ingestion did not cause increases in blood pressure or heart rate, and there was no apparent brain toxicity. Salvia also didn't appear to be addictive. The subjects did, however, report hallucinatory patterns and visitations by "entities."

Salvinorum A is the active ingredient in salvia divinorum, a member of the mint family, which has been used for centuries by Mexican shamans for spiritual purposes. In the past decade, salvia has become increasingly popular as a recreational drug, although the number of its users is small compared to other popular recreational drugs.

Still, the notion that someone somewhere might be getting high legally has prompted legislators in at least 12 states to criminalize its use, possession and sale. Other states, including California, where Miley Cyrus tripped the light fantastic in that video, have imposed restrictions on its availability. In California, one must be 18 to legally use it. Cyrus was celebrating her 18th birthday.