Kratom is a tropical tree native to Thailand and other parts of Southeast Asia, belonging to the same plant family as coffee. Its leaves contain dozens of active compounds that interact with opioid receptors in the brain, producing effects that range from mild stimulation at low doses to pain relief and sedation at higher ones. It’s sold in the U.S. as a powder, capsule, or extract, and millions of people use it to manage chronic pain, ease opioid withdrawal, or boost energy.
Where Kratom Comes From
The kratom tree (Mitragyna speciosa) grows naturally in the tropical forests of Thailand, Malaysia, Indonesia, and surrounding countries. It’s an evergreen that can reach over 80 feet tall in the wild. For centuries, laborers in Southeast Asia chewed fresh kratom leaves or brewed them into tea for a mild energy boost during long workdays. Today, most kratom sold in the West comes from Indonesian farms, where leaves are harvested, dried, and ground into a fine powder for export.
How It Works in the Body
Kratom leaves contain alkaloids, which are naturally occurring compounds that make up roughly 0.5 to 3% of the leaf’s total weight. The dominant one, mitragynine, accounts for 51 to 82% of the total alkaloid content. It binds to the same brain receptors that morphine and other opioids target, but with some important differences.
Mitragynine is a partial agonist at the mu-opioid receptor, meaning it activates that receptor only partially rather than fully. Several of kratom’s minor alkaloids share this trait. In animal studies, some of these compounds provided pain relief comparable to traditional opioids but caused significantly less respiratory depression, which is the primary way opioid overdoses kill. Some alkaloids also did not trigger a signaling pathway (called beta-arrestin-2 recruitment) that is linked to constipation, tolerance, and breathing suppression with conventional opioids.
Beyond opioid receptors, mitragynine also appears to act on adrenergic receptors, which are involved in the body’s stress and alertness systems. This dual activity helps explain why kratom’s effects feel different from those of a standard painkiller.
Dose-Dependent Effects
Kratom’s effects shift dramatically depending on how much you take. At doses below about 5 grams of raw leaf powder, most people report stimulant-like effects: increased energy, alertness, and sociability, similar to strong coffee. Between roughly 5 and 15 grams, the experience tilts toward relaxation, pain relief, and sedation. This dual nature is one of the most distinctive things about kratom and one of the reasons it appeals to such different groups of users.
Strains and Vein Colors
Kratom products are typically marketed as red, white, or green vein varieties, sometimes with regional names like “Maeng Da” or “Bali.” These labels mostly reflect differences in how the leaves are processed after harvest. Red vein kratom undergoes longer drying times or fermentation, which is thought to shift the alkaloid profile toward relaxation. White vein kratom is dried more quickly, and ground stem material is sometimes added to increase stimulating compounds. Green vein falls in between.
In practice, though, lab testing tells a more complicated story. One study comparing multiple commercial strains found no statistically significant differences in mitragynine, paynantheine, speciogynine, or speciociliatine content across products, and no significant difference in total alkaloid content. Mature leaves do contain higher levels of certain minor alkaloids than young leaves, so harvest timing may matter more than the color label on the package. The takeaway: strain names are more of a marketing convention than a reliable guide to what you’ll experience.
Why People Use It
The two most common reasons people seek out kratom are chronic pain and opioid withdrawal. An estimated 40 million Americans live with chronic pain, and some turn to kratom as what they see as a natural alternative to prescription painkillers. Case reports describe patients who attributed substantial pain relief and improved alertness to kratom use.
For opioid withdrawal specifically, kratom’s combination of mu-opioid activation and activity at other receptor types appears to ease withdrawal symptoms while producing milder dependence of its own. One clinical observation found that kratom “attenuates potentially severe opioid withdrawal, yet cessation of kratom administration itself appears to be associated with modest abstinence symptoms.” That said, kratom is not an FDA-approved treatment for anything, and managing opioid dependence carries real risks regardless of the substance involved.
Side Effects and Safety Risks
Common side effects at moderate doses include nausea, vomiting, sweating, drowsiness, and tremor. At higher doses, kratom can cause agitation, high blood pressure, confusion, and hallucinations. Overdoses have been associated with seizures, coma, and death, though fatal cases often involve other substances.
Liver damage is a rarer but serious concern. Chronic recreational use has been linked to acute liver injury, typically appearing within 1 to 8 weeks of regular use. Early signs include fatigue, nausea, itching, dark urine, and then jaundice. A review of 85 reported cases found an average onset of about 21 days. In severe cases, the liver damage can be accompanied by kidney failure and bone marrow toxicity.
Contamination is another issue. FDA testing of 30 commercial kratom products found significant levels of lead and nickel, with some products containing concentrations many times above safe daily exposure limits for an oral supplement. One product tested at 29,000 nanograms per gram of nickel. Because kratom is sold as a supplement rather than a regulated drug, there are no mandatory purity standards, and quality varies enormously between vendors. A multistate salmonella outbreak in 2018 was also traced back to contaminated kratom products.
Dependence and Withdrawal
Regular kratom use can lead to physical dependence. People who develop moderate to severe dependence report withdrawal symptoms including insomnia, muscle aches, nausea, abdominal cramping, sweating, runny nose, irritability, restlessness, and depressed mood. Symptoms generally appear within 12 to 48 hours after the last dose and typically last 1 to 3 days, though some people experience them for up to a week. Compared to withdrawal from traditional opioids like heroin or prescription painkillers, kratom withdrawal is generally described as milder, but it’s far from trivial for heavy users.
Legal Status in the U.S.
Kratom leaf products are legal at the federal level in the United States, though several states and municipalities have banned or restricted them. The FDA has never approved kratom for any medical use and has issued multiple warnings about its safety. A 2016 attempt by the Drug Enforcement Administration to classify kratom as a Schedule I substance was withdrawn after significant public pushback.
More recently, in 2024, the FDA took a targeted step by recommending that 7-hydroxymitragynine (7-OH), a concentrated compound derived from the kratom plant, be scheduled as a controlled substance. This recommendation specifically targets synthetic or concentrated 7-OH products sold as tablets, gummies, and drink shots. The FDA made clear it is not focused on natural kratom leaf products. The DEA is reviewing the recommendation and would need to complete a public rulemaking process before any scheduling takes effect. There are currently no FDA-approved 7-OH drugs, and the compound cannot be lawfully added to dietary supplements or conventional foods.