A synthetic derivative of the kratom plant is killing people in Los Angeles. Over the weekend, local health officials reported three new overdose deaths tied to the opioid-like compound 7-hydroxymitragynine, or 7-OH. The Los Angeles County Department of Public Health announced the latest fatalities on Friday, October 10, bringing the total to six deaths reported recently in the area. Most of these deaths involved generally healthy adults who had other drugs in their system, particularly alcohol. Federal and local health agencies have started to crack down on these illicitly sold products, which typically contain much more 7-OH than found in natural kratom. “It’s critical that the community understand that these products are dangerous and can result in fatal overdoses,” said Gary Tsai, Director of the Los Angeles County Department of Public Health’s Substance Abuse Prevention and Control Bureau, in a statement. A more dangerous version of kratom Kratom is the name given to the leaves of the tree Mitragyna speciosa. It contains numerous compounds that combine to provide users a stimulant-like effect at lower doses and an opioid-like effect at higher doses. Kratom proponents have long argued that the drug, usually sold as an herbal or dietary supplement, can be used to safely manage chronic pain or as an alternative treatment for opioid use disorder (people with this condition often take other less harmful and addictive opioids to manage their dependence). So far, though, health agencies largely haven’t agreed. For years, the FDA has warned the public to stay away from natural kratom, arguing that these unregulated products can carry some of the same serious health risks as other opioids. While kratom is not a controlled substance, no legal use of it exists in the U.S., including as a dietary supplement, and some states have outright banned it. Whatever the potential risks of natural kratom are, however, they seem to pale in comparison to synthetic 7-OH products. Though it can depend on the exact variety, the leaves of the kratom plant typically contain only a small percentage of 7-OH (less than 2% of the total alkaloid content). But synthetic products are often concentrated in 7-OH, with levels two- to sixfold higher than would be expected from natural kratom products, according to a recent FDA report. Compared to mitragynine—the main alkaloid compound in kratom—7-OH also appears to be more chemically similar to other opioids. As such, these synthetic products can reliably cause the same symptoms caused by a classical opioid overdose, including severe respiratory depression (shallow or slowed breathing) and death. Taking action Earlier this summer, the FDA announced that it would be taking action to curb synthetic 7-OH use. These actions included sending warning letters to companies selling these products and a recommendation for the Drug Enforcement Administration to start listing synthetic 7-OH as a controlled substance. Natural kratom supporters like the American Kratom Association have also warned people to stay away from so-called synthetic kratom and have applauded the FDA’s crackdown on these and similar products. For now, though, these products remain readily available in vape shops, gas stations, or online. LA health officials have told the public to avoid using 7-OH or kratom products. But barring that, they state that people shouldn’t use these products alone or without a supply of naloxone (the opioid overdose reversal treatment) and that they should avoid mixing these products with other drugs like alcohol that can worsen an overdose.