Cannabinoids and Saliva Tests: What a Result Really Means
Partager
Which substance is targeted by a THC saliva test?
Saliva tests dedicated to cannabis generally target delta-9-tetrahydrocannabinol, or delta-9-THC, present in saliva after consumption. CBD is not THC and should not be presented as the molecule directly sought.
A product sold as CBD may still contain traces of THC. After consumption, it is this actual presence of THC — not the "CBD" label — that can explain a positive result.
What is a cross-reaction?
Rapid tests often rely on an immunochromatographic reaction. The antibodies used are designed to recognize a target molecule, but they can sometimes react with chemically similar substances. This ability is called cross-reactivity.
Why can two tests give different results?
- they do not target exactly the same molecules;
- their detection thresholds differ;
- the amount of saliva collected and the sampling method vary;
- The time since consumption influences the concentration;
- Food, drinks, medications, or storage conditions can interfere with a test if the instructions are not followed.
What does the 15 ng/mL threshold mean?
The French decree of December 13, 2016 sets a minimum detection threshold of 15 ng/mL THC for roadside saliva screening of cannabinoids. This threshold describes the expected performance of the screening device; it does not constitute a legally authorized amount before driving.
Official confirmation is performed in a laboratory by chromatography coupled with mass spectrometry, according to lower analytical thresholds.
Is a rapid test a definitive diagnosis?
No. A rapid test provides a presumptive result. A positive result may require analytical confirmation depending on the context. A negative result only means that the targeted substance was not detected above the test threshold at the time of sampling.
How to choose a suitable test?
Check the targeted molecule, threshold, analyzed matrix, cross-reactivity data, storage duration, and usage conditions. For cannabis screening in saliva, the Drugdiag® Saliva THC test targets delta-9-THC with a declared threshold of 15 ng/mL.
