Can Ashwagandha Cause a False Positive Drug Test?

Ashwagandha is unlikely to cause a false positive on a standard workplace or forensic urine drug screen, the kind that tests for marijuana, opioids, cocaine, amphetamines, and benzodiazepines. No published research has shown that ashwagandha triggers those panels. But the story is more complicated than a simple “no,” because ashwagandha does interfere with certain medical lab tests, its active compounds do show up in urine, and the supplement itself may contain unlisted ingredients that could trigger a positive result for reasons having nothing to do with the herb.

Why Ashwagandha Raises Suspicion in the First Place

Ashwagandha’s signature compounds are withanolides, a group of steroidal lactones that give the plant much of its biological activity.¹ The word “steroidal” is what makes people nervous. If a supplement contains steroidal compounds, it seems logical to wonder whether a drug test could mistake them for anabolic steroids or other controlled substances. That concern is understandable but mostly unfounded for standard drug panels. The steroidal backbone of withanolides is structurally distinct from the androgens, corticosteroids, and synthetic steroids that drug tests are designed to detect. Immunoassay-based drug screens work by recognizing the shape and binding characteristics of specific drug molecules or their metabolites, and withanolides simply do not fit those antibody targets closely enough to set off alarms on a typical five- or ten-panel test.

What Standard Drug Panels Actually Look For

The drug tests most people encounter at work, in probation settings, or in emergency rooms are immunoassay-based urine screens. They look for a defined list of substance classes: THC metabolites, cocaine metabolites, opiates, amphetamines, phencyclidine, and sometimes benzodiazepines, barbiturates, and a handful of others depending on the panel. These tests use antibodies engineered to bind with metabolites of those specific drugs. When researchers tested a range of popular herbal supplements against standard enzyme immunoassay drug screens, none of the herbs produced false-positive results.² That study looked at ginkgo biloba, saw palmetto, St. John’s wort, ginseng, garlic, green tea, valerian, and cranberry. Ashwagandha was not one of the herbs in that particular panel, which is a gap in the evidence, but the finding is still reassuring: herbal supplements as a class tend not to cross-react with the antibodies used in these screens.

No published study has specifically taken ashwagandha, spiked a urine sample or had volunteers take it, and run the result through a standard multi-panel drug screen. So the honest answer is that there is no direct proof ashwagandha does cause a false positive on those panels, and no direct proof it cannot. What we have is a reasonable inference from pharmacology: the metabolites of withanolides bear little resemblance to the metabolites of THC, cocaine, opioids, or amphetamines. That inference is supported by the broader finding that herbal supplements generally pass through standard drug screens without incident.

Where Ashwagandha Actually Does Interfere With Lab Tests

The documented problem with ashwagandha and lab testing is not about recreational drugs. It is about digoxin, a heart medication. Digoxin blood levels are monitored closely in patients because the drug has a narrow therapeutic window, meaning the difference between an effective dose and a toxic one is small. Several immunoassay platforms are used to measure digoxin in blood, and ashwagandha cross-reacts with at least one of them in a clinically meaningful way.

In one study, researchers found that ashwagandha produced significant apparent digoxin concentrations in drug-free serum when measured by the fluorescence polarization immunoassay, a widely used testing method. The microparticle enzyme immunoassay and the Beckman assay showed minimal interference. When ashwagandha extract was added to serum that already contained actual digoxin, the fluorescence polarization assay gave falsely elevated readings, while the microparticle assay actually produced falsely lowered values.³ The same study tested whether ashwagandha interfered with immunoassays for 11 other commonly monitored drugs and found no interference with any of them. A separate study confirmed this pattern, reporting that ashwagandha produced modest apparent digoxin concentrations on the Digoxin III assay in the range of roughly 0.31 to 0.57 ng/mL in supplemented drug-free serum, while a different assay platform showed no apparent digoxin at most concentrations tested.⁴

This matters in a specific, practical way: if you take ashwagandha and are also on digoxin therapy, or if you end up in a clinical setting where digoxin levels are checked, the test may read as though you have digoxin in your system when you do not, or may misrepresent the actual level of digoxin if you are taking it. This is not a “drug test” in the way most people mean the phrase, but it is a false positive in the laboratory sense, and it could lead to real clinical consequences like unnecessary treatment adjustments. If you take ashwagandha and have any reason to get digoxin levels checked, mentioning the supplement to your doctor is worth doing.

Withanolides Do Show Up in Your Urine

One question people reasonably ask is whether ashwagandha’s active compounds are even detectable in urine at all. The answer is yes. A recent study gave healthy older adults either 240 or 480 mg of a commercial ashwagandha extract and collected urine over the following twelve hours. Using highly sensitive mass spectrometry methods, researchers detected four withanolides in participant urine: withaferin A, sominone, viscosalactone B, and an unidentified metabolite not found in the original supplement, suggesting the body transforms some withanolides into new compounds during digestion.⁵ Overall recovery was low, with less than three percent of the ingested withanolides turning up in urine. But the point is that these compounds are absorbed, metabolized, and excreted. They are physically present in urine after you take ashwagandha.

The fact that withanolides appear in urine does not mean they will trigger a standard drug screen, for the reasons discussed above. The mass spectrometry techniques used to find them are far more specific and sensitive than the immunoassay screens used in workplace drug testing. It is the difference between a forensic chemist analyzing exactly which molecules are present versus a screening test asking a yes-or-no question about a handful of drug classes. Standard screens are not looking for withanolides and are unlikely to confuse them with the drug metabolites they are designed to catch.

The Bigger Risk Is What Else Might Be in Your Supplement

Here is where the false-positive conversation takes a genuinely concerning turn, and it has nothing to do with ashwagandha itself. Dietary supplements are not subject to the same pre-market testing and approval process as pharmaceuticals. Analytical studies have found that anywhere from 14 to 50 percent of dietary supplement products tested positive for anabolic agents or other prohibited substances not listed on the label.⁶ The contamination can come from manufacturing facilities that process multiple products, from deliberate spiking to make a product “work better,” or from poor quality control at any stage of production.

This means that even if pure ashwagandha will not cause a false positive, the ashwagandha product you buy could contain unlisted substances that will cause a very real positive. The test result would be correct in detecting a banned substance; the surprise is that the substance came from a supplement you thought contained only an herb. This is the mechanism through which athletes have been sanctioned, employees have failed workplace tests, and patients have had unexplained lab results. The contamination risk is not unique to ashwagandha. It applies to essentially all dietary supplements, especially those marketed for energy, muscle building, weight loss, or sexual performance, where the incentive to spike with active pharmaceutical ingredients is highest.

If you are subject to drug testing and want to minimize risk, look for supplements that carry third-party certification from programs like NSF Certified for Sport, Informed Sport, or USP Verified. These programs test finished products for banned substances and contaminants. No certification eliminates risk entirely, but they substantially reduce it compared to uncertified products.

Ashwagandha and Hormone Levels

A separate issue worth understanding is that ashwagandha can change your actual hormone levels, which matters in contexts where hormone markers are part of what is being tested. In a randomized, placebo-controlled trial of overweight men, ashwagandha supplementation led to an 18 percent greater increase in DHEA-S and a roughly 15 percent greater increase in testosterone compared to placebo.⁷ These are real physiological changes, not artifacts of a faulty test.

For most people, a modest bump in DHEA-S or testosterone is unlikely to push values outside normal laboratory reference ranges or trigger any clinical concern. But in anti-doping contexts, where athletes are subject to biological passport programs that track hormone levels over time, any unexplained change in an athlete’s testosterone-to-epitestosterone ratio or DHEA-S trends could prompt further investigation. The World Anti-Doping Agency does not currently list ashwagandha as a prohibited substance. However, an athlete whose hormonal profile shifts after starting ashwagandha supplementation could find themselves in an uncomfortable conversation, especially if the supplement also turns out to be contaminated with an unlisted anabolic agent.

For a person undergoing routine workplace drug testing, the testosterone or DHEA-S change is irrelevant. Standard drug panels do not measure hormone levels. But anyone navigating competitive sport, fertility treatment, or hormone-sensitive medical conditions should be aware that ashwagandha is not hormonally inert.

Other Supplements and False Positives

Ashwagandha is far from the only supplement people worry about. Hemp-derived CBD products are probably the most common source of supplement-related false positives because many contain trace amounts of THC that can accumulate with regular use. Certain over-the-counter medications are well-known culprits too: ibuprofen has historically interfered with some THC assays, and pseudoephedrine can trigger amphetamine screens on older platforms.

Among herbal supplements specifically, the evidence is thin for most causing false positives. The study that tested eight common herbal supplements against enzyme immunoassay drug screens found that none of them cross-reacted.² The herbs that do raise legitimate concern tend to be those with structural similarities to controlled substances, like certain alkaloid-containing plants, or those frequently sold in formulations spiked with synthetic compounds. Ashwagandha falls into neither category. Its withanolides are steroidal lactones, but that steroidal structure does not translate into cross-reactivity on panels designed to detect amphetamines, opioids, or cannabinoids.

What Happens If You Do Get a Positive Result

If you take ashwagandha and receive a positive result on a urine drug screen, the first thing to know is that an initial immunoassay screen is just a screening step. Any positive result on a standard immunoassay should be confirmed by a second test using a more precise method, typically gas chromatography-mass spectrometry or liquid chromatography-tandem mass spectrometry. These confirmation tests identify the exact molecules present in the sample, so they can distinguish between a withanolide and an amphetamine, or between a plant sterol and an anabolic steroid. A substance that fools an immunoassay’s antibody through structural resemblance will not fool a confirmation test that reads the molecule’s actual chemical fingerprint.

In practice, this means that even in the unlikely scenario where ashwagandha’s metabolites somehow produced a screening-level positive, the confirmation test would clear it. The concern is really about the time, stress, and administrative hassle that can follow a preliminary positive, especially in workplaces that suspend employees pending confirmation or in legal contexts where a preliminary result carries immediate consequences. Knowing that you can request confirmation testing, and that such testing is standard protocol, is useful.

Telling Your Doctor About Ashwagandha

The digoxin assay interference documented in the research points to a broader principle: supplements can affect lab results in ways that neither you nor your doctor expect if nobody knows you are taking them. Ashwagandha’s interaction with digoxin immunoassays was only discovered because researchers specifically looked for it. There may be other assay interactions that have not been studied yet. The evidence that ashwagandha’s withanolides are absorbed and excreted in urine, including at least one metabolite that was not even present in the original supplement, reinforces the idea that the body processes these compounds in ways we are still mapping out.⁵

Listing ashwagandha on your medication and supplement intake whenever you have lab work done is a low-effort precaution that can prevent a confusing result from turning into an unnecessary workup. This is especially true if you are taking cardiac medications, undergoing hormone testing, or managing a condition where precise lab values drive treatment decisions. The pharmacist or lab technician may not always know whether a specific supplement interacts with a specific assay, but having it on the record means the clinical team can investigate if something looks off rather than chasing a phantom diagnosis.