The Department of Public Health issued a warning to residents and health care providers about the drug, which is not approved for medical use and is estimated to be up to 50 times as potent as morphine. MGM-15 has been detected in products marketed as “uncaria tomentosa,” also known as cat’s claw, and has been identified in Utah and Washington.

Officials did not release details about the person who died or the circumstances of the overdose. The city alert included an image of a small purple container labeled “Script botanicals x Maui labs” and “paradise blend” and “berry punch.”

Health officials said they believe naloxone, commonly sold as Narcan, can reverse MGM-15’s effects. The warning underscores the risk posed by potent substances appearing in products sold as botanical or wellness items, including at smoke shops and gas stations.

The alert followed another recent warning sign in the city’s overdose crisis: San Francisco earlier reported its first fatal overdose linked to cychlorphine, a synthetic opioid estimated to be 10 times more potent than fentanyl. In that case, the victim, a teenager, was believed to have taken the drug in counterfeit pills.

Separately on Wednesday, San Francisco police said they served search warrants at two smoke shops in the Haight-Ashbury and Inner Richmond after a months-long investigation. Officers seized hundreds of products suspected of containing kratom or psilocybin mushrooms, along with nitrous oxide canisters and other items police described as illegal. Authorities have not said whether any seized products contained MGM-15.