Seizures of illicit ketamine by drug enforcement agents have surged throughout the United States, growing 349% from 2017 through 2022, a new study finds.

Rising use of ketamine could increase the likelihood that people who use the drug recreationally may instead get a potentially harmful version of the substance, researchers say.

"This dramatic rise in ketamine seizures by law enforcement may be indicative of rising nonmedical and recreational use," said study co-author Joseph Palamar, a researcher in the Center for Drug Use and HIV/HCV Research at NYU School of Global Public Health.

"Unlike illegal ketamine years ago, most illegally obtained ketamine today is not pharmaceutical grade and is sold in powder form, which may increase the risk that it contains other drugs such as fentanyl," Palamar said in a school news release.

Unintentional exposure to fentanyl can lead to overdose and death.

Ketamine is referred to as a "dissociative anesthetic hallucinogen" because it makes patients feel detached from their pain and environment, according to the U.S. Drug Enforcement Agency. It is commonly prescribed off-label to treat chronic pain and depression.

Loosened prescribing restrictions during the COVID-19 pandemic may have led to an industry of pop-up clinics prescribing ketamine online and off-label, the study noted.

"Though the risk of overdose from ketamine alone is low, some people who use the drug report negative dissociative side effects, such as feeling dizzy or nauseous," Palamar said.

Palamar has written extensively on "club drugs" like ketamine, ecstasy and others. He's concerned that any illegal powder in the United States may be contaminated with fentanyl. It is currently showing up in heroin and cocaine.

Promotion of prescription ketamine in recent years is also fueling black-market use and availability, Palamar said.

Researchers also found that the total weight of ketamine seized in the United States increased from 127 pounds in 2017 to about 1,550 pounds in 2022. This represents growth of more than 1,100%.

Tennessee, Florida and California had the most seizures of the drug. However, it's not clear whether those states have the highest usage.

The research was supported by the U.S. National Institute on Drug Abuse. The study results were published May 24 in the journal JAMA Psychiatry.