Undeclared Kratom Alkaloids and Tianeptine in Products Labeled as Cat's Claw

Background: High-concentration 7-hydroxymitragynine (7-OH) products have been described by the US Food and Drug Administration as an emerging public health concern, and in August 2026 the Drug Enforcement Administration temporarily placed mitragynine pseudoindoxyl (MP), MGM-15 (dihydro-7-hydroxymitragynine), and MGM-16 in schedule I. Since July, Utah and Tennessee officials have reported overdoses, deaths, and laboratory findings involving tablets labeled as cat's claw (Uncaria tomentosa), an herbal supplement without known opioid activity. Chemical data on such products are scarce, and consumers cannot tell from the label which opioid-active compounds they contain. Methods: In a cross-sectional analysis, we purchased 46 chewable or unit-dose products labeled as containing cat's claw from online retailers and 3 gas stations in Mississippi during September 2026. The products represented 17 brands. Methanol extracts were analyzed by ultra-high-performance liquid chromatography with photodiode array detection and compared with a methanol extract of botanically verified U tomentosa bark. Liquid chromatography quadrupole time of flight mass spectrometry identified additional compounds, and compounds were quantified against authentic reference standards. Proportions are reported with exact (Clopper-Pearson) 95% CIs. Results: None of the 46 products declared kratom alkaloids or their derivatives, yet all contained at least one component. Mitragynine was quantified in 41 products (89%; 95% CI, 76% to 96%), 7-OH in 35 (76%; 95% CI, 61% to 87%), MGM-15 in 24 (52%; 95% CI, 37% to 67%), and MP in 22 (48%; 95% CI, 33% to 63%). A total of 39 products (85%; 95% CI, 71% to 94%) contained MP or MGM-15, which are temporarily controlled in schedule I. Tianeptine, an antidepressant not approved in the US, was present in five products (11%; 95% CI, 4% to 24%) at 27.9 to 40.2 mg per unit. The 7-OH content ranged from 0.01 to 95.4 mg per unit. Eight products carrying claims such as "NO KRATOM and No 7-OH" or "NO 7-OH" contained mitragynine, 7-OH, and 3-dehydromitragynine. Conclusions: Labels gave consumers no reliable guide to exposure. Clinicians evaluating unexplained opioid toxicity after use of a cat's claw product should consider kratom-derived opioids and tianeptine. Regulators may need product testing and label enforcement in addition to scheduling of individual compounds.