San Francisco health officials on Wednesday, Oct. 21, 2026, warned the public about MGM-15, a kratom-derived opioid that killed an adult in the city in late September. It is the first known death from the drug in San Francisco.

Why it matters: The drug was found in tablets sold in smoke shops and gas stations under labels that do not mention kratom or opioids. CBS San Francisco reported it is estimated to be up to 50 times more potent than morphine.

  • The product: “Script botanicals x Maui labs” tablets marketed as “uncaria tomentosa” or “cat’s claw.”
  • Naloxone (Narcan) is expected to reverse an MGM-15 overdose. Give it and call 911.

What MGM-15 is

MGM-15, chemically dihydro-7-hydroxymitragynine, is a semi-synthetic opioid made from compounds in kratom, according to the San Francisco Department of Public Health (SFDPH). It has no approved medical use, and taking too much can cause a fatal overdose. The U.S. Drug Enforcement Administration recently made it a Schedule I substance, so it is illegal to sell.

The drug has also turned up in overdoses in Utah and Washington state, the department said.

How the San Francisco case was found

The Office of the Chief Medical Examiner detected MGM-15 in the person who died and in the packaging of the product they had taken, SFDPH said. Officials have not released the person’s name, age or neighborhood.

The brand involved here is different from the products identified in Utah and Washington, the department said. Its packaging makes no reference to kratom or 7-hydroxymitragynine (7-OH), two substances that have drawn public attention recently. That is part of the concern: a buyer may have no idea the tablets contain an opioid.

SFDPH published photos of the packaging with its alert so shoppers and health care providers can recognize it.

Second synthetic opioid warning this year

In April, SFDPH warned about cychlorphine, a synthetic non-fentanyl opioid found in a counterfeit pill that killed a 16-year-old. San Francisco police said at the time that cychlorphine, estimated to be 10 times more powerful than fentanyl, could be found in fake pills made to look like Xanax, Adderall and OxyContin, CBS reported. No further cychlorphine deaths have been detected, the department said.

The medical examiner continues to test for new and emerging substances, including both drugs, and shares results with the health department.

Where to get naloxone and help

  • Free naloxone is available at the SFDPH Behavioral Health Services Pharmacy, 1380 Howard St., weekdays from 9 a.m. to 6 p.m. It is also sold at most retail pharmacies.
  • SFDPH describes MGM-15 as a mu-receptor agonist and said it has no reason to believe timely naloxone would fail to reverse it.
  • For treatment for opioid use disorder or to speak to an addiction specialist, SFDPH’s line is 888-246-3333.
  • Organizations can request naloxone and group trainings through the SFDPH Naloxone Clearinghouse Project.