The Washington Poison Center warned the public Oct. 6 that some supplements sold as cat’s claw are counterfeit products spiked with concentrated kratom-related chemicals that behave like strong opioids. The poison center said the products are causing opioid overdoses and severe withdrawal, and that poison centers nationwide, including in Washington, are treating patients who used them.
The warnings, now issued by health officials in Utah, Tennessee, Virginia and Washington, point to a growing problem: a supplement experts consider generally harmless is being used as cover for potent, unlabeled opioid-like compounds, Becker’s reported Oct. 5. Herbal supplements such as cat’s claw are not inspected or approved by the FDA, so their safety and contents are not guaranteed, the Virginia Department of Health said Sept. 17. Because the packaging does not list these chemicals and standard urine drug screens cannot detect them, consumers and clinicians may not recognize what is causing an overdose or withdrawal.
Here are eight things to know about cat’s claw and the current safety concerns:
1. What cat’s claw is. The National Center for Complementary and Integrative Health describes cat’s claw as a woody vine that grows wild in the Amazon and other tropical parts of Central and South America. Most U.S. commercial products use the Uncaria tomentosa species, and the herb is promoted for osteoarthritis, rheumatoid arthritis, cancer and viral infections, NCCIH said. Memorial Sloan Kettering Cancer Center notes the vine’s bark has traditionally been used for gastric and inflammatory conditions and is sold today as a supplement for immune, digestive and joint health.
2. The evidence behind it is limited. Few high-quality human trials have been done, and no conclusive evidence supports using cat’s claw for any health purpose, NCCIH said. Memorial Sloan Kettering said the herb has not been shown to be effective for cancer or AIDS and that more studies on safety and effectiveness are needed.
3. The real herb is not an opioid, but it carries its own cautions. Authentic cat’s claw is not psychoactive and does not cause opioid overdose or withdrawal, according to the Washington Poison Center. NCCIH said it appears safe taken by mouth for up to six months, but it may slow blood clotting, could worsen autoimmune symptoms and may be unsafe during pregnancy. Memorial Sloan Kettering said reported side effects include nausea, diarrhea and stomach discomfort, and the herb may interact with blood thinners and some antiretroviral drugs.
4. Testing has found hidden kratom compounds. U.S. poison centers have flagged cat’s claw products containing unlabeled kratom alkaloids and synthetic kratom derivatives, including 7-hydroxymitragynine, or 7-OH, the Virginia Department of Health said. Utah Department of Agriculture and Food testing found Buzzers Cat’s Claw tablets contained mitragynine pseudoindoxyl and MGM-15. Tennessee officials have also detected MGM-15 in products sold as cat’s claw, and a Tennessee Bureau of Investigation special agent called them “kratom in disguise.”
5. The compounds can cause overdose and dependence. The Washington Poison Center said 7-OH, MGM-15 and mitragynine pseudoindoxyl act on the same brain receptors as morphine, heroin and fentanyl and are added to fake products at highly concentrated levels, which can slow or stop breathing. Reported effects include central nervous system depression, respiratory depression and rhabdomyolysis, along with dependence and opioid-like withdrawal after chronic use, according to the Virginia Department of Health. Chris Holstege, MD, director of UVA Health’s Blue Ridge Poison Center, told NBC News that kratom can act like an opioid at higher doses and interact with pain medications and other sedatives.
6. Cases and deaths have been reported. The Utah Poison Control Center has reported four confirmed deaths involving cat’s claw, the Washington Poison Center said. Utah’s poison center began fielding calls in March from people who developed opioid overdose-like symptoms after taking products labeled cat’s claw. More broadly, poison center calls tied to kratom rose 1,200% from 2015 to 2025, according to CDC data.
7. Where the products are sold, and which brands are implicated. The fake products have turned up in vape shops, gas stations, convenience stores and online, the Washington Poison Center said. As of Oct. 7, only the Buzzers and Homiez brands had been tied to kratom alkaloids through investigations in other states, and Washington officials do not yet know which brands are linked to patients there, the poison center said. Wildwood Recovery, an addiction treatment provider in Thousand Oaks, Calif., cautioned that label claims such as “7-OH free” or “kratom-free” do not rule out other opioid-active compounds. Wildwood said people who switch from 7-OH to these tablets may simply shift their dependence to a different product.
8. Regulators are tightening controls. In August, the DEA temporarily placed mitragynine pseudoindoxyl, MGM-15 and MGM-16 in Schedule I, and at least nine states have banned kratom. In Washington, Mount Vernon became the first city in the state to ban kratom in September, and Arlington city officials are weighing an ordinance that would bar the commercial sale, distribution and advertising of kratom products, KING 5 reported. Under the Arlington proposal, the city could deny, suspend or revoke business licenses for violations, but personal possession and use would remain legal. NCCIH said supplement makers, not the FDA, are responsible for vetting product safety and labeling before sale.
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