Kratom is generally detectable in blood for about 24 to 48 hours after your last dose. But the full picture is more nuanced than that window suggests, because kratom’s main active compound can linger in your body much longer depending on how much you took and how often you use it.
The 24 to 48 Hour Detection Window
Blood tests can pick up kratom’s primary alkaloid, mitragynine, for roughly one to two days after ingestion. Blood concentrations peak within one to two hours of swallowing kratom, then steadily decline as your liver breaks down the alkaloids and your body clears them. This relatively short detection window is why blood testing for kratom is mostly used in clinical or emergency settings rather than routine screening.
The second major alkaloid in kratom, 7-hydroxymitragynine, follows a similar pattern in blood and is also detectable for approximately 24 to 48 hours. However, it clears faster at the cellular level, which matters when we look at half-life data.
Half-Life Varies Dramatically by Dose
A drug’s half-life is the time it takes for half of it to leave your bloodstream. For mitragynine, that number changes significantly based on how much kratom you consume. A 2024 pharmacokinetics study in humans found the following half-lives after a single dose:
- Low dose (~6.6 mg mitragynine): about 8.5 hours
- Moderate dose (~13 mg): about 16 hours
- Higher dose (~27 mg): about 29 hours
- High dose (~53 mg): about 43 hours
That’s a massive range. At a low dose, mitragynine is mostly gone from your blood within a day. At a high dose, the half-life alone stretches nearly two full days, meaning trace amounts could persist even longer than the typical 48-hour detection window suggests.
7-hydroxymitragynine clears much faster. After a single dose, its half-life ranges from roughly 1.7 hours at low doses to about 4.7 hours at high doses. This compound exits your bloodstream significantly quicker than mitragynine.
Regular Use Extends Clearance Time
If you take kratom daily, the numbers shift considerably. With repeated dosing, mitragynine builds up in your system and takes longer to clear. The same study found that after multiple daily doses, half-lives increased across the board:
- Low dose: half-life rose from 8.5 to about 26 hours
- Moderate dose: from 16 to about 44 hours
- Higher dose: from 29 to about 68 hours
A half-life of 68 hours means it takes nearly three days just to eliminate half the mitragynine in your blood. Full elimination (typically five to six half-lives) could take well over a week for a regular user taking moderate-to-high amounts. So while a blood test still has a practical detection window of a couple of days, the compound itself may linger at very low levels for much longer in habitual users.
How Your Body Processes Kratom
Your liver does the heavy lifting. Mitragynine is broken down primarily by a liver enzyme called CYP3A4, with smaller contributions from a few other enzymes in the same family. This matters for two practical reasons. First, anything that slows down CYP3A4, including certain medications like some antifungals and antibiotics, can delay how quickly your body clears kratom. Second, individual genetic differences in how active these enzymes are can make clearance faster or slower from person to person.
Other factors that influence how long kratom stays in your blood include age (older adults tend to metabolize substances more slowly), body fat percentage, hydration, and overall liver health.
Kratom and Drug Testing
Standard workplace drug screens, including the common 5-panel and 10-panel tests, do not test for kratom. Most employers don’t include it. Kratom’s alkaloids are structurally different from opioids, amphetamines, and the other substances those panels target, so it won’t trigger a false positive.
Specialized kratom tests do exist. These are typically ordered in specific circumstances: probation or parole monitoring, military testing, or clinical evaluations where kratom use is suspected. If a test is specifically designed to detect mitragynine, the blood detection window remains that 24 to 48 hour range. Urine tests, which are more commonly used, can detect kratom for a longer period, generally up to about a week.
Blood Concentration Levels
For context on what blood tests actually measure: surviving patients in clinical case reports have shown blood mitragynine concentrations ranging from 5 to 340 nanograms per milliliter. No established lethal dose exists for kratom in humans, and concentrations in fatal cases have varied enormously (from 3.5 to over 7,000 nanograms per milliliter), often with other substances also present. Doses up to about 53 mg of mitragynine, equivalent to roughly 4 grams of dried leaf, have been well tolerated in controlled research settings.