7-OH and kratom vaping products: an emerging public health threat

Non-nicotine vaping products containing cannabinoids, nutraceuticals, vitamins, and essential oils have been rapidly gaining popularity. Most recently, vapes containing kratom and kratom-derived compounds have emerged in vape shops and online marketplaces with flavors and packaging appealing to adolescents. Kratom (Mitragyna speciosa), a tropical tree in the Rubiaceae family native to Southeast Asia, contains over 40 structurally related indole and oxindole alkaloids, exhibiting opioid-like properties (Kerrigan and Basiliere 2022). Traditional uses involve chewing fresh leaves or brewing tea for pain relief, increased energy, and management of opioid withdrawal symptoms. The primary psychoactive constituents include mitragynine, comprising up to 66% of total alkaloid content, and its metabolite 7-hydroxymitragynine (7-OH), typically present at 2% of total alkaloid content but significantly more potent at opioid receptor activation.

Kratom products have expanded to include powdered leaf material, concentrated extracts, and recently, vaping formulations, readily available in gas stations, smoke shops, online retailers, and at kratom bars (Anderer 2025). While kratom has been available in the United States for decades, products containing concentrated kratom constituents have emerged in recent years (Anderer 2025). One of the primary psychoactive components of kratom, 7-hydroxymitragynine, or 7-OH, has been rising in popularity as a recreational drug due to its high binding affinity for opioid receptors and subsequent potential for addiction (FDA 2025). 7-OH is available in the form of tablets, extracts, drinks, shots, gummies, and candies, often featuring appealing flavors and packaging. Because 7-OH is not present in high concentrations in kratom, it is produced semi-synthetically, with instructions easily found online, presenting a risk for unknown contaminants with solvents, metals, and catalysts (FDA 2025). In 2025, the FDA recommended Schedule I classification for 7-OH products, distinguishing synthetic derivatives from natural leaf preparations, due to its increased risk for opioid addiction (Kerrigan and Basiliere 2022). Additionally, 7-OH exhibits effects similar to classic opioids such as respiratory depression and withdrawal symptoms (FDA 2025). Notably, neither the FDA’s report on 7-OH nor a recent JAMA article mentioned the presence of 7-OH in vaping products, despite their potential increased risk for harm (Anderer 2025; FDA 2025).

Kratom and 7-OH vapes are found in a variety of forms, often containing 7-OH, kratom extract, and/or proprietary ingredient blends, and sometimes combined with hemp extract. Vaping of kratom and 7-OH presents several additional safety concerns compared to oral ingestion, including (i) altered pharmacokinetics and pharmacodynamics, (ii) formation of thermal degradation products, and (iii) the potential for local respiratory toxicity (Gordon et al. 2022). Hence, in addition to the well-known negative health effects of opioid use, 7-OH and kratom vapes have the potential to produce significant respiratory injury due to unknown byproducts and contaminants from their semi-synthetic production.

Kratom alkaloids contain reactive centers that could make them vulnerable to decomposition during vaping. The hydroxyl group of 7-OH is not only tertiary and benzylic, but it is also located allylic to the indole N = C group (Chakraborty et al. 2021a). This arrangement makes 7-OH particularly subject to reaction, either by dehydration or in a pinacol-type rearrangement process. Indeed, the product of the pinacol process, mitragynine pseudoindoxyl (MP), a potent multifunctional mu-opioid receptor agonist and delta/kappa-opioid receptor antagonist, is usually found in isolates containing 7-OH (Basiliere and Kerrigan 2020; Chakraborty et al. 2021a; Chakraborty et al. 2021b). While the formation of oxidative products from the mitragynine family has not been studied in great detail, 3-dehydromitragynine (3DM), a toxic iminium electrophile formed by oxidation at the tertiary hydrogen center, has been identified as a non-enzymatic product of the parent alkaloid (Chakraborty et al. 2021a).

It is of some note that significant oxidative decomposition has been found in other vaping products, such as those containing cannabinoids (Love et al. 2025). CBD and THC readily oxidize during vaping to give quinones and related semi-quinones, compounds shown to be highly reactive toward thiols, to generate reactive oxygen species, and to induce inflammatory responses in the respiratory epithelium, particularly under high-power or dry-puff conditions (Love et al. 2025). Like cannabinoids, 7-OH and other kratom alkaloids are prime candidates for decomposition at temperatures typical of vaping (200 to 350 °C) or smoking (600 to 900 °C) (Basiliere and Kerrigan 2020; Begum et al. 2025). Kratom vaping products have not been clearly defined, but of the known products of the parent alkaloid, one—MP—has potent biological activity and another—3DM—is a reactive electrophile with known toxicity (Chakraborty et al. 2021a). As such, evaluation of the chemical composition of these products before and after vaping is critical for the identification of potential harmful degradation products and to evaluate actual delivered doses of 7-OH and mitragynine.

Existing in vitro work has primarily investigated kratom as a chemosensitizer in airway and immune cell lines. These studies have generally found that low-alkaloid kratom extracts exhibit increased cytotoxicity compared to purified alkaloid extracts and have the ability to modify inflammatory pathways (Domnic et al. 2021; Bayu et al. 2024; Rahmawati et al. 2024). Critically, there are no published studies using physiologically relevant in vitro models such as primary human airway epithelial cells or in vivo inhalation models to assess kratom alkaloid toxicity. Thus, the direct effects of vaping or inhaling kratom on lung tissue remain unknown.

Kratom and 7-OH vaping products are a public health threat, with exposure to kratom and 7-OH products already leading to 1690 and 165 cases across US poison centers in 2025, respectively (Devitt 2025; Reif et al. 2025; Smallets et al. 2025; Wightman and Hu 2025). Case reports indicate that 7-OH has significant potential for abuse and harm due to the development of dependence and subsequent withdrawal. 7-OH and kratom vaping products are currently unregulated in all but 7 states and are often sold alongside tobacco and cannabis vapes. The proliferation of these products poses a major regulatory and public health challenge as they feature fruit and dessert flavors appealing to younger users. The American Kratom Society is lobbying to maintain consumer rights and emphasizing the differences between the health benefits of Kratom and the dangers of 7-OH. Hence, research is urgently needed on their pulmonary health effects, especially concerning the presence of potential contaminants leftover from the synthesis of 7-OH and potentially toxic thermal degradation products from heated aerosolization. Furthermore, the extra-pulmonary effects of 7-OH and kratom vaping should be considered, given that inhaled exposure bypasses first-pass metabolism (FDA 2025; Patil and Sarasija 2012). Although poison centers have received reports of serious health effects related to the use of 7-OH and the FDA is aware of the presence of other 7-OH products, it is critical that public health officials, physicians, and consumers are cognizant of the unknown health effects of kratom and 7-OH vaping and the potential for both pulmonary injury and addiction (Devitt 2025).

Funding

This work was supported by a Ruth L. Kirschstein National Research Service Award (NRSA) Individual Predoctoral Fellowship (F31 fellowship) from the National Heart, Lung, and Blood Institute (KDS; 1F31HL179957-01).

Conflicts of interest. The authors declare no conflicts of interest.