What Can Cause a False Positive for Kratom? The Lab Science, Both Ways

What can cause a false positive for kratom? On the published record we found, one thing: methadone and its main metabolite, EDDP, which at high concentrations can make one kratom screening test read positive. The question also runs the other way. A 2020 report linked kratom use to false-positive results on one screening test for EDDP. Those are two separate findings, both published as conference abstracts rather than full papers, and in both it was mass spectrometry, not the screen, that told the false results from the true ones. We sell kratom extracts, so we also say plainly what a positive means for our own customers, and what to ask if a result matters to you now.

Two questions inside one search

People mean one of two things by this question, and the evidence differs.

Direction one: kratom setting off a test for another drug. The one published report we found covers a single screening test for EDDP, methadone's main metabolite.

Direction two: something else setting off a kratom test. The one published report we found points to methadone and EDDP, running the other way.

Both are conference abstracts, and neither one's PDF was open to us. Keep them apart. Neither says kratom causes false positives for opioids in general, and when we searched PubMed and the wider web for reports of kratom setting off fentanyl, opiate, buprenorphine or tramadol screens, we found none. That does not prove it never happens, only that nobody has published it where we could find it.

How a screening test gets fooled

In both reports the urine met a screen first and mass spectrometry second. The screens were immunoassays, which rely on an antibody, and antibodies are not perfectly choosy. SAMHSA's 2012 guide to clinical drug testing in primary care puts it in one line: "Substances other than the drug to be detected may also cross-react with the antibody and produce a false-positive result." The guide predates every kratom test on this page, so we use it for general principles only.

The maker of the CEDIA kratom screen scores cross-reactivity as a percentage. Mitragynine at the 50 ng/mL cutoff scores 100 percent. EDDP read positive when tested at 60,000 ng/mL and scores 0.08 percent, which is 50 divided by 60,000, times 100, on our arithmetic. Small is not zero. At a high enough concentration, a weak cross-reactant can still cross the cutoff.

Direction one: kratom and a false-positive methadone-metabolite screen

The report is a conference abstract from the University of Virginia's Department of Pathology, published on October 28, 2020, in a supplement of the American Journal of Clinical Pathology. It began with one emergency-department patient whose urine screened positive for EDDP while mass spectrometry found neither methadone nor EDDP. The patient later said they had used kratom powder.

The team then pulled routine-care specimens from three non-contiguous months that flagged on the Thermo Scientific CEDIA Methadone Metabolite (EDDP) immunoassay but were negative on a separate methadone screen. Forty-eight qualified, and each was retested by liquid chromatography with a QTOF mass spectrometer for methadone, EDDP, mitragynine and a second kratom alkaloid, the one we call the concentrated minor alkaloid. Half of them, 24 of the 48, held one or both kratom alkaloids and no methadone or EDDP. Sixteen (33 percent) did hold methadone or EDDP, none of them with kratom alkaloids, and 17 percent were negative for all four compounds.

A methanol extract of kratom powder in urine gave no EDDP signal at all, and drug-free urine spiked with mitragynine or the concentrated minor alkaloid at 10,000 ng/mL gave only "indeterminate" screens. After enzymatic hydrolysis, which cleaves glucuronide conjugates, the kratom-positive specimens showed a significantly larger rise in EDDP-screen absorbance than the methadone-positive ones (p=0.0031). The title blames "A Kratom Metabolite", but the abstract never says which one. The conclusion is hedged: the authors' studies "suggest that a Kratom metabolite can cause false positive results" on that one immunoassay.

What it does not say matters as much. One EDDP kit, not methadone tests in general. No rate among kratom users, since 24 of 48 is half of a group already picked for a suspicious result. Clinical testing, not workplace testing. And it was mass spectrometry, not the screen, that showed those 24 specimens had no methadone or EDDP in them.

What can cause a false positive for mitragynine?

Kratom-specific screens exist. Thermo Fisher's CEDIA Mitragynine (Kratom) Assay screens urine for mitragynine at a 50 ng/mL cutoff and is labeled "For Criminal Justice and Forensic Use Only". Its insert is blunt: "This is a screening test. All positive results must be confirmed via GC/MS or LC-MS/MS." It also warns: "It is possible that substances other than those investigated in the specificity study may interfere with the test and cause false results."

In the maker's specificity tables, one opiate or opioid compound read positive: EDDP, at 60,000 ng/mL. Fentanyl, buprenorphine, morphine, oxycodone, methadone, tramadol and the rest of that table read negative at 100,000 ng/mL, though methadone at that level "may have semi-quantitative values around 20-30 ng/mL." About 60 structurally unrelated drugs, from antidepressants to ibuprofen, read negative too.

Kratom's own compounds read positive at high concentrations: mitragynine acid at 300 ng/mL (16.7 percent), 9-hydroxycorynantheidine at 3,125 ng/mL (1.6 percent), paynantheine and speciociliatine at 25,000 ng/mL (0.2 percent each), and the concentrated minor alkaloid at 35,000 ng/mL (0.14 percent). That is not a false positive for kratom. A screen that reacts to speciociliatine is still detecting kratom, even when the result says mitragynine. Every figure here comes from the maker spiking drug-free urine, and none of them predicts a real person's result.

The real-world test came from Quest Diagnostics, in a conference abstract in Clinical Chemistry published on October 2, 2025. Urine screened on the CEDIA Mitragynine immunoassay from September to November 2024 was retested by LC-MS/MS whenever it screened positive. Of 395 screen positives, 346 (87.6 percent) confirmed and 49 (12.4 percent) did not.

Only 23 of those 49 came with methadone results, and 19 of the 23 (82.6 percent) held methadone and EDDP. The other 26 had no methadone data. So this does not show that 12.4 percent of kratom positives are really methadone. It shows that where methadone results existed, most unconfirmed positives came from urine holding methadone and EDDP.

Spiking backed it up. Methadone at 100 ug/mL and EDDP at 100 ug/mL both produced positive mitragynine screens, as did kratom's own speciociliatine, speciogynine and paynantheine. The authors conclude that high concentrations of methadone and EDDP "may interfere and cause false positive results for mitragynine screening", and note that the insert reports methadone at that level as negative, "in contrast with our current findings".

Why it matters: the authors say providers want mitragynine screening "for patients in treatment programs for substance use disorder and pain management". Methadone is one of the three medicines with the evidence base for opioid use disorder, so a patient on prescribed methadone is exactly who this finding concerns.

Kratom's own alkaloids: positive for kratom, not quite for mitragynine

The paper that turns up in searches as a kratom testing review is something else: an original study from the Karolinska University Laboratory in Stockholm, published in Drug Testing and Analysis (online November 4, 2022, in print 2023). It has no immunoassay data. Its lesson is that mass-spectrometry methods have limits too.

Twenty-nine urine samples had tested positive for mitragynine at a 100 ug/L cutoff on the laboratory's routine LC-HRMS method, which "did not separate mitragynine from speciogynine and speciociliatine." Better chromatography found all four sister compounds, mitragynine, speciogynine, speciociliatine and mitraciliatine, in every sample. Mitragynine made up 5.5 to 53 percent of the total, and in 8 samples (28 percent) mitragynine alone came to 11 to 78 ug/L, below the cutoff. Every sample still pointed to kratom: the four compounds "originated from the intake of kratom (i.e., plant material)".

The legal frame is Swedish. Mitragynine is classed as a narcotic in Sweden and the other three compounds and the plant are not, so none of this is a United States rule. The warning travels, though: routine methods "may focus solely on mitragynine and the other three diastereomers are not covered or indistinguishable."

What can cause a false positive for kratom, in one table

Five findings in the same columns. Check the direction first.

Read down the confirmation column. In every row built on real specimens, a more specific mass-spectrometry method settled what the first test could not, and in the Swedish row even the routine method was mass spectrometry. Nothing in these sources says confirmation is perfect.

Screening result versus confirmed result

HHS's Mandatory Guidelines for Federal Workplace Drug Testing Programs define an initial drug test as "An analysis used to differentiate negative specimens from those requiring further testing", and a confirmatory test as "A second analytical procedure performed on a separate aliquot of a specimen to identify and quantify a specific drug or drug metabolite." DOT's rule at 49 CFR 40.85 is as plain: "If the result is at or above the cutoff concentration, you must conduct a confirmation test."

Clinical testing works differently. From SAMHSA's guide: "In clinical settings, however, confirmatory testing is at the practitioner's discretion. Laboratories do not automatically perform confirmatory tests." Both false-positive reports above come from clinical testing, the setting where confirmation is a choice. The same guide's line for a patient who disagrees: "if the patient disputes the unexpected findings, a confirmatory test should be done."

Is kratom on a standard drug test panel?

Not on either federal panel. The HHS authorized testing panels published on March 13, 2026, unchanged since July 7, 2025, cover marijuana and cocaine metabolites, codeine, morphine, hydrocodone, hydromorphone, oxycodone, oxymorphone, 6-acetylmorphine, phencyclidine, fentanyl, amphetamine, methamphetamine, MDMA and MDA. No mitragynine or other kratom alkaloid is listed, and no methadone or EDDP either.

The DOT panel is closed by rule. 49 CFR 40.82 says: "As a laboratory, you must test for the following five drugs or classes of drugs in a DOT drug test. You must not test 'DOT specimens' for any other drugs." That covers DOT tests only. We found no primary source defining what a commercial 5-, 10- or 12-panel test contains, so we will not guess. Kratom-specific screens do exist, though, and someone has to choose to run one, as Quest did on clinical specimens in 2024.

The medical review officer, prescriptions and the split specimen

In the federal programs, a laboratory positive goes to a medical review officer, the MRO, before it reaches the employer. Under the HHS guidelines the MRO is "A currently licensed physician", and when a positive comes in, "the MRO must contact the donor to determine if there is any legitimate medical explanation for the positive result." If the donor documents one, a valid prescription being the guidelines' own example, "the MRO reports the test result as negative to the agency." Passive exposure to a drug, such as marijuana smoke, and food products containing one, such as poppy seeds, are ruled out as legitimate medical explanations by name.

DOT's rules, in Subpart G of 49 CFR Part 40, say the MRO "must offer the employee an opportunity to present a legitimate medical explanation in all cases", but "The employee has the burden of proof that a legitimate medical explanation exists." Staff may advise an employee to have prescriptions ready for the interview. The MRO "must not consider any evidence (verbal or written information) from any drug tests that are not collected or tested in accordance with this part", and an explanation that "would not, even if true, constitute a legitimate medical explanation" is no basis for a negative.

Under the HHS guidelines, a donor whose primary (A) specimen is reported positive can ask, through the MRO, for the split (B) specimen to be tested by a second HHS-certified laboratory, and has 72 hours from the MRO's notification to ask. DOT's rule also gives the employee 72 hours from the MRO's notice, and under DOT the employee does not have to pay up front, though the employer may seek reimbursement.

Neither rulebook mentions kratom, and kratom is on neither panel, so whether it comes up with an MRO at all depends on what the laboratory found. These rules cover federal agencies and DOT-regulated employers. Outside them, ask a lawyer or the program running the test. None of this is legal advice.

When the positive is real: adulterated kratom products

One way kratom ends up beside a positive for another drug is not a false positive at all: the product had another drug in it. The DEA's temporary order on O-desmethyltramadol (O-DSMT), published on August 12, 2026, records that "O-DSMT was found to be mixed with the kratom plant as determined by testing of the packaging material and the confirmation of both O-DSMT and mitragynine in toxicology results of individuals." The blend was sold as Krypton, "a mix of kratom and O-DSMT", and the order cites Swedish reports from 2009 of nine deaths due to intoxication with O-DSMT combined with mitragynine.

In one German case in 2010, the urine was "negative for tramadol or its metabolites using the immunoassays", while LC-MS/MS found kratom alkaloids and about 9 mg/L of O-DSMT. The screen missed a drug that was there, the reverse of a false positive. A positive for a drug added to a product is a true positive for that drug, not kratom producing a false result. These are Swedish and German cases from 2009 and 2010, not a United States finding.

What this means if you use our products

Here is the part a seller would rather skip. Every King K product is a mitragynine product, liquid extracts and kratom shots alike. If you use them and then take a kratom-specific test, a positive is a true positive. And nothing in the 2020 EDDP finding sets our products apart from other kratom. We make no claim about whether or when any of our products would or would not show up on a test.

A product certificate does not change that. A certificate of analysis tests a sample of a product, not a person, and says nothing about how anyone's drug test will read. If you want to see what one does show, you are welcome to ask us about a certificate for your lot.

If a result matters to you right now

Our advice: treat it as a question about chemistry and paperwork.

Know which result you have. Ask whether it is a screen or a confirmed result, which drug it names, and whether a positive was confirmed by GC/MS or LC-MS/MS.

Say so if you dispute it. In clinical testing, that is when SAMHSA's 2012 guide says a confirmatory test should be done.

Bring your prescriptions, methadone included, to the clinician or the MRO.

Mind the clock. Under the federal rules above, a split-specimen request has a 72-hour window.

Answer truthfully, and take legal questions to a lawyer and health questions to a clinician.

We are not going to tell you how long kratom stays in your system or how to change a result; that is not what a false-positive question is about. If you find a figure on this page that its source no longer supports, tell us.

False positive questions

What can cause a false positive for kratom?

On the published record we found, methadone and its metabolite EDDP at high concentrations, on the CEDIA Mitragynine immunoassay. The maker's table shows EDDP reading positive, and a 2025 Quest Diagnostics conference abstract found methadone and EDDP in 19 of the 23 unconfirmed positives that had methadone data. Nothing else is documented, though the maker says untested substances may interfere.

Can kratom cause a false positive for methadone?

One 2020 conference abstract linked kratom use to false-positive results on one test, the Thermo Scientific CEDIA Methadone Metabolite (EDDP) immunoassay, a screen for methadone's main metabolite rather than for methadone itself. Mass spectrometry found kratom alkaloids and no methadone or EDDP in 24 of the 48 flagged specimens studied. We found no report of kratom causing a false positive on any other drug screen.

Is kratom on a standard drug test?

Not on the federal HHS workplace panel or the DOT panel, and DOT laboratories must not test DOT specimens for other drugs. Kratom-specific screens exist, and a national laboratory ran one in 2024, but someone has to order one.

Does a positive kratom screen mean I used kratom?

Not on its own. A screen is preliminary: the maker of one kratom screen says every positive must be confirmed by GC/MS or LC-MS/MS, and 12.4 percent of one national laboratory's 2024 screen positives did not confirm. A screen set off by other kratom alkaloids is still detecting kratom.

If I use King K products and a kratom test is positive, is that a false positive?

No. Every King K product contains mitragynine, so a positive on a kratom-specific test after using one is a true positive, not a false one. We make no claim about whether or when any product will or will not show up on a test.

Disclaimer: this page summarizes publicly available material as of October 19, 2026, and links to primary sources so you can check them. The two false-positive findings are conference abstracts, and the cross-reactivity figures are the manufacturer's, from spiked urine; none of them predicts any individual result. It is general information, not legal or medical advice, and no substitute for counsel in your jurisdiction or for a clinician. Statements about botanical products have not been evaluated by the Food and Drug Administration, and no product is intended to diagnose, treat, cure or prevent any disease.