Oral fluid (saliva) testing is not a valid measure of cannabis impairment or timing of use. A meta-analysis of seven clinical trials (116 participants) found highly inconsistent THC levels, even among people consuming identical amounts, making these tests unreliable for determining recent use or impairment. In contrast to breathalyzers for alcohol, saliva tests often flag users long after effects have faded, leading to false positives and misclassification.
