Contrave is a prescription weight management medication that combines two active ingredients, naltrexone hydrochloride and bupropion hydrochloride, in an extended release tablet. Employers and donors sometimes ask whether a patient taking Contrave can fail a workplace or program drug screen. The honest answer has two parts, because the two ingredients behave very differently on a drug test panel. Naltrexone has no documented history of causing a false positive on any standard immunoassay panel. Bupropion, the other half of Contrave, has a long documented history of producing false positive results on some amphetamine immunoassays. This post explains what the research actually shows, why a presumptive positive is never the end of the story, and how the medical review officer process resolves it when a donor has a valid prescription.
What Is Actually in Contrave
According to the approved by FDA product label on DailyMed, Contrave extended release tablets contain naltrexone hydrochloride, an opioid antagonist, and bupropion hydrochloride, an aminoketone antidepressant also marketed on its own as an antidepressant and smoking cessation aid. The two drugs are combined for chronic weight management in adults, used together with diet and exercise. Neither ingredient is a controlled substance, and neither is itself an amphetamine or an opiate. What matters for drug testing is how the immunoassay screening chemistry reacts to each one and its metabolites, not what the medication is prescribed for.
Naltrexone and the Opiate Screen
Naltrexone blocks opioid receptors and is also sold alone as Vivitrol and generic naltrexone for alcohol and opioid use disorder treatment. Because it is chemically related to opioid antagonists rather than to morphine type opiates, naltrexone does not register as a positive on standard opiate immunoassay panels and there is no credible published cross reactivity evidence showing that it does. A donor taking naltrexone, whether as Contrave or as a standalone product, should not expect it to trigger an opiate screen. The confirmation step, when performed, uses gas chromatography mass spectrometry or liquid chromatography mass spectrometry to identify specific molecules, and naltrexone's structure does not match morphine, codeine, or their metabolites.
Bupropion and the Amphetamine Immunoassay
Bupropion is the ingredient that drives the real question behind this topic. Case reports and laboratory studies going back decades have documented that bupropion and its metabolites can cross react with some amphetamine class immunoassays, producing a presumptive positive result on a screening test for amphetamines or methamphetamine even though the donor has not used either drug. One of the earliest published case reports, titled Amphetamine positive toxicology screen secondary to bupropion, described exactly this scenario in a patient prescribed bupropion. A later laboratory study, Bupropion metabolites produce false positive urine amphetamine results, identified the specific bupropion metabolites responsible for the cross reactivity. A follow up study measuring how often this happens in practice, Frequency of false positive amphetamine screens due to bupropion using the Syva EMIT II immunoassay, found that the interference is immunoassay dependent, meaning it shows up on some screening platforms and panel chemistries and not on others. This is the pattern seen across many prescription medications: the presumptive screen is a chemistry reaction, not a direct identification of a specific drug molecule, so cross reactivity with unrelated compounds is a known and studied limitation of immunoassay technology.
Screening Versus Confirmation: Why the Panel Type Matters
A workplace or program urine drug test almost always starts with an immunoassay screen, the kind of test used in rapid cups and dip cards. An immunoassay works by detecting whether a sample reacts with antibodies tuned to a drug class. It is fast and inexpensive, but it answers only "did something in this sample react," not "which exact molecule caused the reaction." When bupropion metabolites cross react with an amphetamine immunoassay, the result is a presumptive positive that must be confirmed, never a final result on its own. A review summarizing how often common prescription drugs produce this kind of result, Commonly prescribed medications and potential false positive urine drug screens, is frequently cited by toxicology labs for exactly this reason: a long list of ordinary medications can trigger a presumptive positive on one panel class or another, and confirmation testing exists specifically to sort real positives from reactive false positives.
Confirmation testing uses gas chromatography mass spectrometry or liquid chromatography mass spectrometry, methods that identify the exact molecular structure of what is in the sample rather than a chemical reaction pattern. Amphetamine and methamphetamine have distinct, identifiable molecular signatures. Bupropion and its metabolites have a different, equally distinct signature. A confirmation test will not report amphetamine or methamphetamine present unless those specific molecules are actually in the sample. This is the step that separates a screening artifact caused by bupropion from an actual amphetamine or methamphetamine positive, and it is why a single presumptive result should never be treated as a final determination.
| Panel class | What the research shows about Contrave | How it is resolved |
|---|---|---|
| Amphetamine or methamphetamine screen | Bupropion metabolites have documented, platform dependent cross reactivity on some amphetamine immunoassays | GC/MS or LC/MS confirmation identifies the true molecule; MRO reviews the prescription |
| Opiate screen | No credible published cross reactivity evidence for naltrexone | Standard confirmation if a presumptive positive occurs from an unrelated cause |
| THC, PCP, benzodiazepine, cocaine, barbiturate panels | Contrave is not part of these panel classes and has no documented cross reactivity with them | Not applicable to this medication |
What Happens at the Medical Review Officer Step
In federally regulated and most well run workplace drug testing programs, a non negative screening result never reaches an employer directly. It goes to a medical review officer, a licensed physician trained in substance abuse testing interpretation, who contacts the donor, reviews any prescription medications, and determines whether there is a legitimate medical explanation before the result is reported to the employer. The medical review officer process for federally regulated transportation testing is set out in 49 CFR Part 40, Subpart G, which describes how the MRO must verify a positive, dilute, invalid, or adulterated result, including contacting the donor and reviewing legitimate medical explanations such as a current prescription. A donor who is taking Contrave under a valid, current prescription should disclose that prescription to the MRO or collection site, and the MRO's review, combined with a confirmation test when one is run, is what resolves whether a presumptive amphetamine result reflects actual amphetamine use or a bupropion related screening artifact. This process applies regardless of whether the test is for a federally covered safety sensitive position or a private employer program modeled on the same framework.
What Employers, Clinics and Donors Should Do
Employers and testing program administrators should never attempt to interpret a presumptive screening result on their own, and should never ask a donor to explain a result outside the established MRO or equivalent review channel. The appropriate response to a non negative screen is to route it to confirmation testing and a qualified reviewer, not to assume the result proves drug use or to assume it is automatically cleared because a medication exists that can cause cross reactivity. Collection sites and clinics that want more background on how screening and confirmation testing works, and on how the Substance Abuse and Mental Health Services Administration frames workplace testing program design, can review SAMHSA's employer resources. Programs that need confirmation capacity or that want to add lab based testing alongside point of care cups and dip cards can review options through the American Screening Corporation wholesale portal at wholesale.americanscreeningcorp.com.
This post does not provide medical or legal advice, and nothing here should be read as a recommendation to start, stop, or adjust any medication. A donor with questions about how a prescribed medication could affect a specific test should speak with the prescribing provider or the reviewing medical review officer, not attempt to self diagnose a test result.
Related Reading
For background on the other ingredient in Contrave on its own, see Does Naltrexone Show Up on a Drug Test? Vivitrol, Opioid Panels and Treatment Program Testing. For a closer look at bupropion as a standalone antidepressant and smoking cessation medication, see Wellbutrin and Drug Tests: Why Bupropion Triggers Amphetamine False Positives. Employers building or expanding a testing program can review drug test cup options at americanscreeningcorp.com/collections/drug-test-cups.
Frequently asked questions
Does Contrave cause a false positive on an amphetamine drug test?
Contrave contains bupropion, and published case reports and laboratory studies show that bupropion metabolites can cross react with some amphetamine immunoassay platforms, producing a presumptive positive that is not a confirmed amphetamine result. The effect is platform dependent, meaning it happens on some screening chemistries and not others.
Does the naltrexone in Contrave cause a false positive opiate test?
There is no credible published cross reactivity evidence showing that naltrexone causes a false positive on opiate immunoassay panels. Naltrexone is an opioid antagonist, not an opiate, and it is not part of the molecular class that opiate screens are designed to detect.
Will a lab confirmation test clear a false positive caused by bupropion?
Confirmation testing by gas chromatography mass spectrometry or liquid chromatography mass spectrometry identifies the exact molecule present in a sample. It will not report amphetamine or methamphetamine unless those specific molecules are actually present, which is why confirmation separates a bupropion related screening artifact from an actual amphetamine positive.
What should a donor do if they are prescribed Contrave and get a non negative screen?
The donor should disclose the current prescription to the medical review officer or equivalent reviewing physician as part of the standard review process. The MRO reviews prescription documentation and confirmation results before any result is reported to an employer.
Is Contrave the same as testing positive for amphetamines?
No. A presumptive positive on a screening immunoassay is not a confirmed result. Only a confirmation test, combined with medical review officer review, determines whether a non negative screen reflects an actual amphetamine or methamphetamine positive.
Does Contrave show up on standard THC, PCP, benzodiazepine or cocaine panels?
No. Contrave is not part of those panel classes, and there is no documented cross reactivity between naltrexone, bupropion, or their metabolites and those screening chemistries.
This article is general information for employers, donors and testing program administrators. It is not medical or legal advice. Anyone with questions about a specific medication, prescription or test result should consult the prescribing provider, the reviewing medical review officer, or qualified legal counsel.
