The Food and Drug Administration (FDA) advised consumers to avoid using the herb kratom, citing 36 known deaths associated with products containing the substance.

Kratom comes from a plant in Southeast Asia. It is used to treat pain, anxiety, depression, and symptoms of opioid withdrawal, The Washington Post reports. It is also used recreationally, because it produces symptoms such as euphoria, the article notes.

“There is no reliable evidence to support the use of kratom as a treatment for opioid use disorder,” FDA Commissioner Scott Gottlieb said in a statement. “Patients addicted to opioids are using kratom without dependable instructions for use and more importantly, without consultation with a licensed health care provider about the product’s dangers, potential side effects or interactions with other drugs.”

The FDA noted that there have been reports of kratom being laced with other opioids like hydrocodone. The use of kratom is also associated with serious side effects like seizures, liver damage and withdrawal symptoms.