Deaths due to a new synthetic drug called flakka have risen to 18 in just one South Florida county, The New York Times reports.
The drug is inexpensive and causes exaggerated strength and paranoid hallucinations.
Last week police in Fort Lauderdale killed a man who was reportedly high on flakka. He held a woman hostage with a knife to her throat.
Flakka started appearing in low-income neighborhoods in South Florida about six months ago, the article notes.
Synthetic drugs are popular even though they have been banned, the article note.
Drug makers continue to change the drugs' formulations to stay one step ahead of legislators and law enforcement.
"I have never seen such a rash of cases, all associated with the same substance," said James N. Hall of Nova Southeastern University who studies the Florida drug market. "It's probably the worst I have seen since the peak of crack cocaine. Rather than a drug, it's really a poison."
The drug, also called gravel, is available for $5 a vial or less.
Officials say people are ordering small quantities of flakka through the mail. Its main ingredient is a chemical compound called alpha-PVP.
According to the National Institute on Drug Abuse (NIDA), alpha-PVP is chemically similar to other drugs known as "bath salts," and takes the form of a white or pink crystal that can be eaten, snorted, injected, or vaporized in an e-cigarette or similar device.
Vaporizing, which sends the drug very quickly into the bloodstream, may make it particularly easy to overdose, NIDA notes. Alpha-PVP can cause a condition called "excited delirium" that involves extreme stimulation, paranoia, and hallucinations that can lead to violent aggression and self-injury.