Propranolol and Amphetamine Drug Screens
No, propranolol does not cause false-positive amphetamine results on urine immunoassay drug screens. The available evidence does not identify propranolol as a cross-reacting substance with amphetamine immunoassays.
Evidence Review
The guideline literature extensively documents medications that cause false-positive amphetamine screens, and propranolol is notably absent from these lists. 1, 2, 3
Beta-Blockers and Drug Screen Cross-Reactivity
While beta-blockers as a class have been investigated for potential cross-reactivity, only metoprolol has been documented to cause false-positive amphetamine results, not propranolol. 4
- Metoprolol and its metabolites cross-react with amphetamine immunoassays at concentrations as low as 200 μg/mL for the parent drug. 4
- This cross-reactivity is specific to metoprolol's chemical structure and does not extend to other beta-blockers like propranolol. 4
Documented Causes of False-Positive Amphetamine Screens
The American Academy of Pediatrics and American College of Obstetricians and Gynecologists identify the following as established causes of false-positive amphetamine results: 1, 2
- Pseudoephedrine (most common cause, found in over-the-counter cold medications) 1, 2
- Trazodone (via its metabolite m-chlorophenylpiperazine) 3, 5
- Bupropion 1
- Metoprolol (but not other beta-blockers) 4
Clinical Implications
- If a patient taking propranolol has a positive amphetamine screen, the positive result is not attributable to propranolol, and other medications, over-the-counter products, or actual amphetamine use should be investigated. 1, 2
- The American Academy of Pediatrics recommends obtaining a complete medication history including all prescription medications, over-the-counter drugs, and supplements before interpreting any positive drug test. 1, 2
- Confirmatory testing using gas chromatography-mass spectrometry (GC-MS) should always be obtained before making consequential clinical decisions based on immunoassay results, as screening immunoassays are presumptive only. 1, 2, 3
Important Caveats
- False-positive amphetamine screens occur in 3.9-9.9% of positive amphetamine immunoassays in clinical laboratories. 3, 6
- Standard immunoassay screening tests have known limitations in specificity due to cross-reactivity with structurally similar compounds, but propranolol is not among them. 1, 7, 8
- The American Medical Association advises against making punitive decisions based solely on immunoassay screening results without confirmatory testing. 3