Can Buspirone Cause a False-Positive Amphetamine Screen?
No, buspirone is not documented in the medical literature as a cause of false-positive amphetamine urine drug screens.
Evidence Review
The available evidence does not identify buspirone among the medications known to cause false-positive amphetamine results. Multiple comprehensive reviews of cross-reacting substances have been conducted, and buspirone does not appear in these analyses 1, 2, 3.
Documented Causes of False-Positive Amphetamine Screens
The following medications ARE known to cause false-positive amphetamine results and should be considered in your differential:
- Bupropion is the most frequent cause of false-positive amphetamine screens, accounting for 41% of unconfirmed positive results in one large study 4
- Trazodone causes false positives through cross-reactivity of its metabolite m-CPP with amphetamine immunoassays 5
- Aripiprazole has been documented in pediatric case reports to cause false-positive amphetamine screens 6
- Pseudoephedrine in over-the-counter cold medications commonly causes false-positive amphetamine/methamphetamine results 7
- Other antidepressants, antipsychotics, labetalol, fenofibrate, and metformin have also been implicated 3
Critical Clinical Approach
When encountering a positive amphetamine screen in a patient denying use:
- Obtain a complete medication history including all prescription medications, over-the-counter drugs, and supplements before interpreting results 7, 5
- Order confirmatory testing with gas chromatography-mass spectrometry (GC-MS) immediately before making any clinical decisions, as immunoassay screening tests are presumptive only 7, 5, 6
- Never make punitive decisions based solely on immunoassay results without confirmatory testing 5
- Discuss unexpected results with laboratory personnel or toxicologists before taking action 7, 8
Important Caveats
- False-positive amphetamine screens occur in 3.9-9.9% of positive amphetamine immunoassays in clinical laboratories 2
- Many providers have inadequate training in interpreting urine drug test results, and incorrect interpretation can have severe consequences including legal implications 9, 7
- Establishing a working relationship with your local toxicologist is recommended for consultation on complex results 9, 5