Authorities have linked the product to at least two suicides in Louisiana, and to 21 calls to poison control centers in Florida, the South Florida Sun-Sentinel reported.
"We're seeing teenagers experiment with this," said Dr. Nabil El Sanadi, chief of emergency medicine for Broward Health. "They will do stuff that they wouldn't normally do, like dive from a third-story window into a pool. It's very, very dangerous."
The products contain a chemical called methylenedioxypyrovalerone, or MDPV. It stimulates the central nervous system and produces a high said to mimic that from cocaine or methamphetamine.
The Drug Enforcement Administration said the chemical can cause intense panic attacks, psychosis and addiction, but it has no current plan to ban it.
The product is usually snorted when used illegally and a half-gram bottle can sell for as much as $30.
"It makes people lose touch with reality," said Dr. Cynthia Lewis-Younger, director of the Florida Poison Information Center in Tampa. "They're ending up in psychiatric institutions."
The chemical isn't approved for medical use in the United States, and the United Kingdom banned it in April after linking it to several deaths.