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A member asked:
Can st johns wort cause a false positive on a drug screening?
7 doctors weighed in across 3 answers
No: St. John's wort can affect certain of the liver's metabolic pathways, but would not cause a false positive on a urine drug screen. If there's any question about a substance appearing on the initial screen, confirmatory tests are performed anyway.
Answered 4/14/2016
5k views
Depends: Screening tests can sometimes have false positives and some drugs are associated with these, but not st john's wort. When a screening test is positive it should be confirmed by a confirmatory test such as mass spectrometry / gas chromatography.
Answered 5/1/2019
4.7k views
Yes : Be sure the lab sends the sample to undergo definitive testing by gas chromatography and mass spectrometry. This will clarify the results.
Answered 4/14/2016
2.8k views
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