The Food and Drug Administration (FDA) has issued a warning to people across the country about kratom, an opioid-like herbal supplement used to overcome addiction and treat pain, saying it is potentially deadly, reports.

Last week, FDA Commissioner Scott Gottlieb, MD, said in a statement that scientists at the health agency have taken steps to better understand how the pain-relieving plant works in the body. Their research revealed that compounds in the herb have structures that are highly similar to opioid painkillers and have a high potential for abuse, addiction and serious health consequences. The agency also stated that there is no evidence to indicate that kratom is safe or effective for any medical use.

Kratom is a plant typically native to Malaysia, where the leaves are traditionally crushed and made into a tea to treat pain as well as ease symptoms of heroin or morphine dependence and withdrawal. It is often sold online and in health food shops in powders and pills and has thus far been loosely regulated by the FDA.

However, researchers at the agency say they are now concerned about kratom’s growing use among people suffering from opioid addiction, especially in light of the opioid epidemic in the United States. The FDA also warned that kratom use is linked to serious side effects, including seizures, respiratory depression and even death.

Last year, the agency reported 36 deaths associated with kratom use. In last week’s announcement, Gottlieb updated that figure to 44 fatalities. “The reports underscore the serious and sometimes deadly risks of using kratom and the potential interactions associated with using this drug,” he was quoted as saying. “As the scientific data and adverse event reports have clearly revealed, compounds in kratom make it so it isn’t just a plant — it’s an opioid.”