(NewsNation) — A street drug that can worsen opioid overdoses is increasingly making its way across the U.S.

The drug is known as “tranq” on the streets, but xylazine is actually a large animal sedative that has muscle relaxing properties. When mixed with heroin or fentanyl, it can become deadly.

Xylazine can also cause open wounds and sores, which can become severe enough to require amputation if left untreated. Drugs like naloxone, which can reverse opioid overdoses, aren’t effective against it.

Xylazine restricts blood flow through skin tissue, which is why it can cause ulcers on the skin. In those struggling with addiction, those wounds may go untreated and uncleaned, leading to more problems.

Vice News reported the use of xylazine has risen dramatically since it was first detected in Philadelphia in 2006. Tranq makes opioids stronger and the effects last longer. Withdrawal from tranq can cause seizures, and there has been no research into medications to help ease withdrawals.

Tranq is also less expensive, which is another reason it can be used to cut opioids or other drugs, including cocaine and methamphetamine. People may be unaware the drug they’re using has been cut with tranq and could be stronger than expected, leading to an overdose.

Tranq has spread from Philadelphia throughout the country, recently being detected in San Francisco, where at least four cases of the drug were found in overdose victims last year.

According to the San Francisco Chronicle, the city’s medical examiner plans to retest all overdoses from 2022 to see if xylazine was present and will test for it in all cases going forward and in an attempt to better understand how widely the drug has spread.