It’s possible to test positive for illegal drugs without taking one.

This is least when it comes to initial urine SCREENING tests.

Certain substances can cause false positives on urine immunoassay-based screens...but the same sample will come back negative with a stricter laboratory-based test such as gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC).

SCREENING tests for opiates and amphetamines often result in false positives.

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