(The Hill) — The Food and Drug Administration on Tuesday said it would restrict imports of xylazine, an animal tranquilizer that has “increasingly been found” in illicit drugs like fentanyl and heroin.

Under the import alert, xylazine shipments are subject to heightened FDA scrutiny, and FDA staff may detain shipments of xylazine and the ingredients used to make it to ensure they’re meant for legitimate use.

The agency said it is coordinating with animal health stakeholders to ensure that drugs containing xylazine are available to veterinarians. 

Xylazine is FDA-approved for use in animals as a sedative and pain reliever. Veterinarians legitimately use drug products containing xylazine to sedate large animals such as horses and deer, but it is not safe for use in people and may cause serious and life-threatening side effects, the agency said.

“The FDA remains concerned about the increasing prevalence of xylazine mixed with illicit drugs, and this action is one part of broader efforts the agency is undertaking to address this issue,” Commissioner Robert Califf said in a statement. 

“We will continue to use all tools at our disposal and partner with the Drug Enforcement Administration and other federal, state, local agencies and stakeholders as appropriate to stem these illicit activities and protect public health,” Califf said.

As part of their entry review, FDA said agency staff will consider specific evidence offered by importers that the incoming product is properly labeled, not adulterated and for legitimate veterinary use.

FDA said there have been increasing reports of serious side effects from individuals exposed to fentanyl, heroin and other illicit drugs contaminated with xylazine. But it’s difficult to determine what role the drug itself plays in deaths. Some of the drug’s side effects are similar to an opioid overdose, but can’t be reversed by naloxone. 

Xylazine is not an opioid, but it can depress breathing, blood pressure, heart rate and body temperature to critical levels, FDA said.

Additionally, people who inject drugs containing xylazine can develop severe skin wounds and patches of dead and rotting tissue that easily become infected and, if left untreated, may lead to amputation, the FDA said.