7-OH: The United States’ Atypical Opioid

Written by Izabella Zakatsiolo

In the rainforests and wetlands of Southeast Asia grows a tree whose leaves have been deeply woven into the region’s traditional medicine and labor culture. Traditionally used for its energizing and analgesic properties (NIDA, 2026), kratom contains 7-Hydroxymitragynine (7-OH), a potent opioid compound derived from the kratom tree, Mitragyna speciosa. Mitragynine is the primary, abundant alkaloid in kratom, while 7-OH is a minor constituent that acts as an active metabolite (Kruegel et al., 2019). This metabolite has become an emerging concern in the United States and has called attention to the Food and Drug Administration (FDA) for its addictive and dangerous properties.

Science Behind 7-OH

Terpenoid indole alkaloids, such as 7-OH, are often characterized by their potent physiological effects on humans and animals. Relevant to the field of medicine, these bioactivities include, but are not limited to, anticancer, analgesic, anti-inflammatory, and antidepressant effects (Omar et al., 2021). In natural kratom leaves, 7-OH constitutes less than 2% of total alkaloid content (FDA, 2025). However, many modern products marketed as “enhanced kratom” contain highly concentrated synthetic or semi-synthetic forms of 7-OH. This creates a powerful and potentially addictive substance that may pose greater risks than traditional kratom preparations. Researchers from Johns Hopkins University indicate that 7-OH can be up to 14-22 times more potent than morphine by weight, under certain experimental conditions (Johns Hopkins, n.d). Biological potency, as used in pharmacology, is a measurement of a drug's bioactivity given in terms of the dosage needed to cause a pharmacological effect (Miles & Perry, 1953). Therefore, if a drug is considered more potent than another, less of the drug is needed to produce an effect.

There are three main G-protein-coupled receptors in the central and peripheral nervous system that opioids primarily bind to: kappa, delta, and mu (Al-Hasani & Bruchas, 2011). These receptors regulate pain, reward, and addiction, with the mu-receptor serving as the primary target for analgesic effects. Opioids bind to these receptors and create an artificial surge of dopamine that floods the brain’s reward circuitry far more intensely than natural rewards like food or exercise. This abnormal dopamine release causes intense euphoria, reinforces repeated drug use, and eventually alters brain chemistry leading to addiction (Dhaliwal & Gupta, 2023).

7-OH has been described as an “atypical opioid” due to its opioid-like analgesic effects, or pain relief, but has a unique mechanism of action that differs from classical opioids like morphine or fentanyl. 7-OH acts as a partial agonist on the mu-opioid receptor, while classical opioids are full agonists (Kruegel et al., 2019). In short, this means that classical opioids trigger the maximum possible biological response, while 7-OH activates mu-opioid receptors to a lesser, sub-maximal degree, even when all receptors are occupied. This sub-maximal activation creates a pharmacological “ceiling effect” built into the drug’s natural chemistry. Because full agonists act as central nervous system depressants, an excessive dose can lead to respiratory depression, and possibly mortality if not promptly treated (Pharmacologycorner, 2013).

In addition to acting as a partial agonist, researchers suggest that 7-OH may exhibit “biased agonism” at the mu-opioid receptor. Classical opioids such as morphine strongly activate multiple intracellular signalling pathways, including beta-arrestin recruitment, which has been associated with respiratory depression and other adverse affects. In contrast, kratom alkaloids including 7-OH appear to preferentially activate G-protein signalling pathways while producing less beta-arrestin activity (Kruegel et al., 2019). This selective signalling profile may contribute to the reduced respiratory depression observed in preclinical studies, although researchers emphasize that this does not eliminate the risk of dependence, overdose, or other opioid-related harms.

Overall, despite its atypical pharmacological profile, the high potency and opioid receptor activity of 7-OH highlights its potential for addiction and harm, especially when delivered in concentrated, unregulated products.

Usage in United States

Kratom use has grown substantially in the United States over the past decade, reflecting its increasing visibility in retail and online markets. A recent national survey from 2021-2023 estimates that approximately 0.68% of adults report past-year kratom use, corresponding to millions of individuals (Mun et al., 2026). Other estimates suggest around 1.6 million past-year users in 2023, with broader prevalence estimates ranging widely depending on methodology (Kopczynski et al., 2026). Although overall prevalence has remained relatively stable in recent years, indicators of exposure and public health impact have increased significantly. For example, U.S. poison centre reports rose dramatically, with over 3 400 cases reported in 2025 alone, representing a roughly 200% increase since 2015. This suggests that while the proportion of users may not be rapidly increasing, the intensity, visibility, and potential risks associated with use are evolving. Together, these findings highlight kratom and 7-OH’s transition from a relatively niche substance to a more widely available and commercially distributed product across the U.S.

Federal Action

As of early 2026, 7-OH is not yet a federally scheduled controlled substance in the U.S, but it faces severe federal restrictions, warning letters, and a formal recommendation for Schedule I classification by the FDA (FDA, 2025). However, several states have already enacted emergency bans, classifying 7-OH as a Schedule 1 substance (WSYX, 2026). For reference, Schedule I substances are drugs with a high abuse potential, no accepted medical use, and a lack of safety under medical supervision. Drugs in this category include heroin, LSD, and MDMA (DEA, n.d).

The evolving legal status of 7-OH demonstrates the difficulty regulators face when responding to newly popular psychoactive substances. While concerns surrounding abuse potential and opioid-like effects have prompted aggressive regulatory action in some states, research on the compound’s long-term safety profile and therapeutic potential remains limited. As a result, debate continues regarding the most appropriate balance between public safety, scientific investigation, and consumer access.

Closing Thoughts

Historically, kratom was primarily sold as a raw powder through specialty smoke shops, requiring users to have some knowledge of preparation and dosing. In contrast, the emergence of concentrated 7-OH extracts has made consumption far more accessible, with products now available in ready-to-use formats such as beverages, tablets, and candies. These products are often packaged to resemble popular wellness drinks or supplements, with branding that emphasizes terms like “natural” or “herbal” (Jackson, 2025), potentially conveying a misleading sense of safety. This shift in formulation and marketing lowers the barrier to entry for individuals with little or no prior knowledge of kratom or opioid-like substances. As a result, users may underestimate the potency of 7-OH and its potential for dependence, increasing the risk of repeated use, withdrawal symptoms, and addiction.

However, because kratom-derived products such as 7-OH act as atypical opioids, their potential role in harm reduction for individuals who use classical opioids warrants consideration. As previously stated, unlike full opioid agonists such as morphine, heroin, and fentanyl, 7-OH demonstrates a ceiling effect on respiratory depression, which may reduce the likelihood of fatal overdose. In this context, access to 7-OH could provide a lower-risk alternative for individuals who might otherwise rely on unpredictable illicit opioids.

As 7-OH products continue to expand across North American markets, policymakers and healthcare professionals face the challenge of balancing potential harm reduction benefits with risks posed by increasingly potent and commercially accessible opioid-like substances. Without stronger research, regulation, and public education, 7-OH may further complicate an already devastating opioid crisis.

References

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