Quick answer: No. Bactrim (sulfamethoxazole/trimethoprim) is an antibiotic, and standard 5- to 18-panel urine drug tests do not look for it. Panels target drugs such as THC, cocaine, opiates, amphetamines and PCP at set ng/mL cutoffs. Any positive screen is preliminary; confirm by GC/MS or LC-MS/MS laboratory testing. Source: American Screening Corp.
- Bactrim is not one of the drug classes on SAMHSA-style panels, so it is not a target analyte.
- Cross-reactivity depends on the specific immunoassay, so read the package insert and confirm any unexpected positive in a laboratory.
- FDA-cleared, CLIA-waived screening cups and dip cards give a preliminary result only; the lab result decides.
Does Bactrim cause a positive drug test?
Bactrim should not cause a positive result on its own. Sulfamethoxazole and trimethoprim are antibacterial agents, and they are not the target of any common drug-of-abuse immunoassay.
Need drug tests for your clinic, program or workplace?
American Screening Corp has supplied FDA-cleared, CLIA-waived tests at wholesale pricing since 2004. Popular options:
Ordering 100+ tests? Request volume pricing.
We cannot promise that no assay anywhere will ever cross-react. Each manufacturer publishes its own cross-reactivity data in the package insert. That is why a preliminary positive is never treated as final.
What does a standard urine drug test detect?
A urine drug test detects specific drugs or their metabolites above a cutoff concentration. The HHS Mandatory Guidelines for Federal Workplace Drug Testing Programs (SAMHSA, as of 2023) list the initial urine test cutoffs below. Many clinical and employer panels use the same or similar values.
| Drug class | Initial cutoff (ng/mL) | Is Bactrim a target? |
|---|---|---|
| Marijuana metabolite (THCA) | 50 | No |
| Cocaine metabolite (benzoylecgonine) | 150 | No |
| Codeine/morphine | 2,000 | No |
| 6-acetylmorphine (heroin marker) | 10 | No |
| Hydrocodone/hydromorphone | 300 | No |
| Oxycodone/oxymorphone | 100 | No |
| Amphetamine/methamphetamine | 500 | No |
| MDMA/MDA | 500 | No |
| Phencyclidine (PCP) | 25 | No |
Non-regulated panels may add benzodiazepines, barbiturates, methadone, buprenorphine, fentanyl, tramadol and others. Antibiotics like Bactrim are not part of those lists.
How long does Bactrim stay in the body?
Detection windows apply to the drugs a panel targets, not to Bactrim, because no standard panel measures it. For reference, DOT-style urine testing under 49 CFR Part 40 covers marijuana, cocaine, amphetamines, opioids and PCP. Detection windows for those drugs vary by dose, frequency of use and individual metabolism.
What should a clinic, court or employer do when a donor reports taking Bactrim?
Record the medication, run the screen as written, and send any non-negative result to a laboratory. Do not make adverse decisions from the screen alone.
Prescription-disclosure checklist
- Ask the donor to list current prescriptions and over-the-counter products before collection.
- Write the disclosure on the custody or intake form, not on the device.
- Read the cross-reactivity table in the package insert for the exact lot of device in use.
- Treat every positive as preliminary and send the specimen for GC/MS or LC-MS/MS confirmation.
- Route medication questions to a Medical Review Officer or the prescriber, as your policy requires.
- Apply the same steps to every donor for consistency.
Screening result versus confirmed result
A screening device is a fast immunoassay that tells you whether a drug class may be present above the cutoff. A confirmation test identifies the specific compound and its concentration. Preliminary results guide next steps, and confirmed results support decisions.
Buyers who need point-of-collection testing can compare our drug test cups with our drug test dip cards. Both are FDA-cleared and CLIA-waived screening formats, with laboratory confirmation available for non-negative results.
Policy points for employers and staffing firms
A written policy should say how medication disclosures are handled and who reviews them. For DOT-regulated positions, 49 CFR Part 40 requires a Medical Review Officer to verify results before an employer acts. For non-DOT programs, follow your state statute and your counsel. If your hiring process also includes screening of candidates, Reveal Background handles employment background checks.
FAQ
Can Bactrim cause a false positive on a urine drug test?
It is not a target of standard panels and is not expected to cause a positive. Assays differ, so check the package insert and confirm any unexpected positive by GC/MS or LC-MS/MS.
Do I need to disclose Bactrim before a drug test?
Disclosure is good practice. Record all prescriptions at intake so a reviewer can evaluate any non-negative result. Follow your written policy and applicable law.
Does Bactrim show up on a DOT drug test?
No. DOT 49 CFR Part 40 panels test for marijuana, cocaine, amphetamines, opioids and PCP. A Medical Review Officer verifies all results.
What should we do with a positive screen?
Treat it as preliminary. Send the specimen for GC/MS or LC-MS/MS confirmation before any action, and document the donor's disclosed medications.
Sources
- SAMHSA: Workplace Drug Testing and the HHS Mandatory Guidelines
- U.S. DOT Office of Drug and Alcohol Policy and Compliance: 49 CFR Part 40
- FDA: Drugs of Abuse Tests
Need help choosing a format or setting up confirmation? Contact American Screening Corp in Shreveport, Louisiana for same-day nationwide shipping.
This is general information, not legal or medical advice.
