“MIT” in kratom refers to mitragynine, the primary active alkaloid in the kratom plant (Mitragyna speciosa). You’ll see “MIT” on product labels, especially concentrated extracts, where it indicates the milligram amount of mitragynine per serving. A label reading “150 MIT” or “150 mg MIT” means the product contains 150 milligrams of this specific compound. Understanding what mitragynine is and how it works helps you make sense of these labels and the widely varying strengths of kratom products on the market.
Mitragynine: The Main Active Compound
Mitragynine makes up roughly 40% of kratom’s total alkaloid content, making it by far the most abundant active compound in the plant. It works by binding to the same receptors that opioid painkillers target (mu-opioid receptors) and also interacts with a second receptor system involved in blood pressure regulation and sedation (alpha-2 adrenergic receptors). This dual action is part of why kratom’s effects feel different from traditional opioids to many users.
Once you consume mitragynine, your liver converts a portion of it into a second compound called 7-hydroxymitragynine, which is a significantly more potent activator of opioid receptors. This conversion is handled by a specific liver enzyme (CYP3A), and it means the effects you feel aren’t just from mitragynine itself but also from what your body turns it into. Anything that interferes with that enzyme, including certain medications and even grapefruit juice, can change how much of the stronger metabolite your body produces.
Why “MIT” Appears on Labels
Raw kratom powder is sold by the gram, and a typical serving ranges from 1 to 5 grams. Because the alkaloid concentration in raw leaf varies by strain, growing conditions, and processing, the actual mitragynine content in a gram of powder can differ substantially between batches and vendors.
Extracts solve this problem by concentrating the alkaloids and labeling them in milligrams. A liquid extract shot might read “150 mg Mitragynine per bottle,” sometimes abbreviated to “150 MIT.” This tells you the standardized amount of the active compound rather than just the weight of plant material. Extracts are far more potent, gram for gram. As little as half a gram of a concentrated extract can deliver effects comparable to 4 or 5 grams of plain powder. That concentration gap is exactly why the MIT number matters: without it, you’d have no way to compare the strength of an extract to raw powder or to another extract.
Several states with Kratom Consumer Protection Acts now require third-party lab testing that verifies alkaloid content. Utah, for example, mandates a certificate of analysis from a certified lab covering both alkaloid levels and contaminant screening. Arizona, Oklahoma, Texas, and Utah also cap 7-hydroxymitragynine (the potent metabolite) at no more than 2% of total alkaloid content in finished products, which prevents manufacturers from spiking extracts with the stronger compound.
How Dose Changes the Effects
Kratom’s effects shift depending on how much mitragynine you take, a pattern researchers call biphasic. At lower doses, up to about 5 grams of raw leaf material, the effects lean stimulant. Users describe increased energy, alertness, and sociability, comparable to a strong cup of coffee. Between roughly 5 and 15 grams, the experience tips toward relaxation, pain relief, and sedation.
This same pattern applies to extracts, just at much smaller volumes. A low-MIT extract might feel energizing, while a high-MIT shot is more likely to produce heavy sedation and pain relief. Mitragynine reaches peak blood levels quickly, within about 50 minutes on average. Its half-life is long, though, averaging around 23 hours. That means the compound lingers in your system well after the noticeable effects fade, which is relevant if you’re dosing multiple times per day or combining it with other substances.
Dependence and Withdrawal
Regular kratom use can lead to physical dependence. In a study of U.S. adults who used kratom more than four times per week (averaging about 62 weeks of regular use), withdrawal symptoms were rated as moderate overall. The most commonly reported symptoms included gastrointestinal upset, restlessness, anxiety, irritability, low energy, difficulty sleeping, and cravings. Some users also reported body aches, depressed mood, restless legs, hot and cold flashes, and runny nose or watery eyes.
The withdrawal profile resembles a milder version of opioid withdrawal, which makes sense given mitragynine’s activity at opioid receptors. Higher MIT products deliver more mitragynine per dose, which can accelerate the development of tolerance and dependence compared to plain leaf powder.
Liver Safety
Chronic kratom use has been linked to rare cases of acute liver injury. When it occurs, symptoms typically appear within 1 to 8 weeks of starting regular use and include fatigue, nausea, itching, dark urine, and yellowing of the skin. A review of 85 reported cases found an average onset of about 21 days. The NIH’s LiverTox database rates kratom as a “likely cause” of clinically apparent liver injury, though the overall frequency remains unclear and the condition appears uncommon relative to the number of people using kratom.
Concentrated extracts with high MIT counts deserve extra caution here because they deliver more alkaloid per serving, potentially increasing the liver’s metabolic burden. This is speculative, as no studies have directly compared liver injury rates between extract and powder users, but the logic of dose-dependent toxicity suggests that more isn’t necessarily better.
Regulatory Status in the U.S.
Kratom and its alkaloids, including mitragynine, are not approved by the FDA for any medical use. The FDA’s position is that kratom is not appropriate as a dietary supplement, a food additive, or a drug product. The agency has worked with U.S. Customs and Border Protection and the Department of Justice to limit the sale of unlawful kratom products. Despite this federal stance, kratom remains legal to purchase in most states, with regulation varying widely. Some states have banned it outright, while others have passed consumer protection laws that regulate it as a legal product with testing and labeling requirements.
Oregon, for example, requires third-party testing for contaminants including heavy metals, pesticides, and mycotoxins. Utah requires certificates of analysis covering both alkaloid content and pathogen levels. These state-level frameworks are the closest thing to quality assurance currently available for kratom products, which is why checking for lab-tested MIT content from a vendor in a regulated state offers more reliability than buying an unlabeled product from an unregulated source.