Description
Kratom is the common name for Mitragyna speciosa, a tropical tree in the coffee family (Rubiaceae) native to Southeast Asia, particularly Thailand, Malaysia, Indonesia, and Myanmar. Its leaves have been chewed or brewed as a tea for centuries in the region, traditionally by workers for energy and stamina, and as a folk remedy for pain, diarrhoea, and opium withdrawal. It contains dozens of alkaloids; the two of most practical relevance are mitragynine (the dominant alkaloid by weight, present at meaningfully higher concentrations than any other) and 7-hydroxymitragynine ("7-OH"), a minor alkaloid normally present only in trace amounts in the natural leaf but disproportionately potent (see the dedicated section below, since this distinction has become the centre of current regulatory attention.)
Kratom's effects are unusually dose-dependent in direction as well as intensity: lower doses tend to produce mild stimulant effects (alertness, sociability, energy), while higher doses shift toward sedation and opioid-like effects (analgesia, relaxation, euphoria). This dual profile, plus its legal ambiguity in many Western countries, has driven a rapid rise in recreational and self-medicating use outside Southeast Asia since the 2000s–2010s, including use by some people attempting to manage pain or opioid withdrawal without a prescribed opioid.
Desirable Effects
- At lower doses: mild stimulation, alertness, increased sociability, reduced fatigue
- At higher doses: analgesia (pain relief), relaxation, mild euphoria, sedation
- Reported easing of opioid withdrawal symptoms in some users trying to reduce or stop opioid use.
Undesirable Effects
- Nausea, vomiting, constipation, dry mouth
- Itching, sweating
- Dizziness
- At higher doses: sedation, and while generally reported as lower-risk than with classical opioids, respiratory depression is possible, especially combined with other CNS depressants (alcohol, benzodiazepines, opioids)
- Tachycardia and hypertension have been reported
- Seizures have been reported, though uncommon
- Liver injury (hepatotoxicity, cholestatic-pattern liver injury) has been documented in case reports and case series, more often associated with concentrated extracts than plain leaf, though the exact cause (an alkaloid itself vs. contaminants/adulterants vs. extraction byproducts) isn't fully established
- Regular, heavy use is associated with tolerance and physical/psychological dependence; abrupt cessation can produce a withdrawal syndrome that resembles a milder form of opioid withdrawal; muscle aches, insomnia, irritability, runny nose, diarrhoea, low mood, and cravings
- Deaths involving kratom have been reported, but attribution is contested. A substantial share of documented kratom-associated deaths involved kratom combined with other substances (opioids, benzodiazepines, or notably kratom products deliberately adulterated with the synthetic opioid O-desmethyltramadol, sold under names like "Krypton"), or involved concentrated/enhanced extracts rather than plain leaf, rather than plain kratom leaf used alone. Some public health voices maintain there's no confirmed death from kratom leaf alone; others (including US FDA/CDC data) have recorded kratom as a contributing factor in a measurable number of overdose deaths. Both things can be true at once, which is why the leaf-vs-concentrate distinction below matters so much for risk.
What does it look like?
Traditionally chewed fresh, or dried and ground into a powder (typically green, tan, or brownish, often colour-labelled by "vein" e.g. "red vein," "white vein," "green vein," referring to the leaf's stem colour and associated with subtly different alkaloid profiles/effects). Sold in the West mainly as loose powder, capsules, or pressed tablets; also increasingly as liquid extract "shots," gummies, and drink mixes. These products are often specifically concentrated/enhanced 7-OH products rather than traditional leaf material.
Method of Use
Traditionally chewed fresh or brewed as a tea. Commercially, most commonly swallowed as capsules or "toss and wash" powder (swallowed directly, often washed down with a drink, sometimes called "tossing"), or mixed into a drink.
Pharmacology
Mitragynine acts as a partial agonist at the mu-opioid receptor with what's described as "biased" signalling. It activates the receptor's analgesic pathway without engaging as strongly with the pathway most responsible for classical opioid respiratory depression, which is the pharmacological basis for the commonly cited claim that kratom carries lower respiratory depression risk than a full opioid agonist like morphine or heroin at comparable analgesic doses. It also acts as an antagonist at kappa and delta opioid receptors, and has some activity at adrenergic (alpha-2) receptors, which likely contributes to its stimulant at low dose profile.
7-hydroxymitragynine, by contrast, is present in only trace amounts in the natural leaf (well under a few percent of total alkaloid content) but is a substantially more potent opioid receptor agonist per unit weight than mitragynine, behaving more like a "full" opioid agonist. Some mitragynine is also converted to 7-OH in the body after ingestion (via hepatic metabolism), meaning a meaningful share of the "opioid" component of a typical leaf dose's effect may actually be mediated through this conversion rather than through mitragynine acting directly. This matters practically because it means the concentration of 7-OH in a product, not just whether "kratom" is present at all, is an important determinant how opioid-like and how risky a given product actually is.
Kratom alkaloids are metabolised via hepatic cytochrome P450 enzymes (notably CYP3A4 and CYP2D6), and also affect P-glycoprotein and UGT (glucuronyltransferase) activity creating real potential for drug interactions with a wide range of other medications metabolised through the same pathways (this is worth being aware of clinically, given how many other drugs share these routes).
7-OH
Over the past few years, a distinct category of product has emerged, sold as tablets, gummies, drink mixes, dissolvable strips, and liquid "shots," often in petrol stations, vape shops, and online that contain concentrated, enhanced, or chemically modified 7-OH, at levels far above what's naturally present in kratom leaf. These are frequently marketed and shelved alongside ordinary botanical kratom, but pharmacologically and in terms of risk they behave much more like a genuine, fairly potent opioid product than like traditional kratom leaf.
Mitragynine binds the Mu-Opiod receptor (MOR) but acts as an antagonist, occupying it without activating it, 7-OH is a genuine partial agonist at MOR. Reported potency relative to morphine varies considerably by route and assay, from roughly 4–5× (subcutaneous, mouse) up to 13× (isolated tissue assay) or higher (oral, partly reflecting morphine's poor oral bioavailability). As of mid-2026, US regulators have moved decisively against this specific category (rather than against kratom leaf itself):
- The FDA formally recommended (July 2025) that concentrated 7-OH products be classified as Schedule I controlled substances, explicitly distinguishing them from natural kratom leaf.
- In July 2026, the DEA began the process of temporarily placing 7-OH above a proposed threshold, together with three synthetic/semi-synthetic related compounds, into Schedule I. The action specifically excludes ordinary botanical kratom containing only naturally occurring trace levels of 7-OH.
- Several US states have already imposed their own emergency restrictions specifically targeting concentrated 7-OH products.
- Industry groups representing conventional kratom consumers (e.g. the American Kratom Association) have broadly supported action against concentrated 7-OH specifically, while raising concern that overly broad drafting could inadvertently capture the naturally-occurring trace 7-OH present in ordinary leaf.
In practice a product marketed simply as "kratom" that's actually a high-potency 7-OH concentrate carries meaningfully different (higher) dependence, withdrawal, and overdose risk than traditional leaf or powder, and users may not appreciate this distinction from packaging alone. Anyone using a kratom product regularly and especially anyone using tablets, shots, gummies, or drink mixes rather than plain leaf/powder should treat it with the same caution as an opioid-class substance, including around dependence and withdrawal management.
History
Kratom has been used in Southeast Asia for centuries, historically chewed by manual labourers for stamina and used in folk medicine for pain, diarrhoea, and easing opium withdrawal. Thailand first restricted it in 1943 (the Kratom Plant Act), reportedly motivated in part by a desire to protect state opium tax revenue as kratom was seen as a cheaper substitute during a period of rising opium prices, and later listed it as a controlled narcotic under its 1979 Narcotics Act. In a significant reversal, Thailand decriminalised kratom entirely in 2021, removing it from its controlled narcotics list (effective August 2021) after having already permitted medical use in 2019.
Western interest grew from the 2000s onward as kratom was marketed as a legal herbal supplement and opioid alternative, particularly in the US. In 2016 the US DEA announced intent to emergency-schedule kratom's active alkaloids as Schedule I, but withdrew the proposal after significant public backlash, a petition against the ban gathered over 120,000 signatures, and the vast majority of public comments submitted opposed scheduling, including from some healthcare professionals and law enforcement figures who argued kratom had a role to play in addressing the opioid crisis. Kratom has remained federally unscheduled in the US since, though the FDA has issued repeated warnings (about contamination and unapproved drug claims) and the DEA has separately designated it a "Drug of Concern." The current 7-OH-specific scheduling action (see above) represents the most significant regulatory move since 2016, and notably targets concentrated products rather than attempting to re-run the 2016 fight over the whole plant.
Law
In the UK, kratom is not listed under the Misuse of Drugs Act 1971, but has been controlled since 2016 under the Psychoactive Substances Act 2016, which bans production, supply, importation, and exportation of any substance capable of producing a psychoactive effect (with exemptions for food, alcohol, tobacco, caffeine, and licensed medicines. Kratom does not fall within these).
- Production, supply (including offering to supply), importation, or exportation maximum sentence: 7 years / unlimited fine / both
- Simple possession for personal use is not an offence under the Act (unlike Misuse of Drugs Act offences), except in a custodial institution (e.g. prison), where possession carries a maximum of 2 years imprisonment
- There is, in practice, no lawful route to buy kratom in the UK, ordering from an overseas seller for delivery to a UK address counts as importation, and packages can be seized at the border
