OSLO, NORWAY — The detection of THC in oral fluid is not necessarily indicative of recent cannabis exposure, according to clinical trial data published in the journal Therapeutic Drug Monitoring.
Investigators assessed the detection time of THC in oral fluid in habitual cannabis consumers during a prolonged period of monitored abstinence. Researchers collected oral fluid samples twice per day for the length of the trial.
Authors identified that THC may be detectable in subjects’ oral fluid samples for a period of up to eight days following cannabis exposure.
Subjects’ oral THC levels fluctuated from negative to positive results during this period despite volunteers failing to reinitiate their cannabis use.
“Findings for THC in oral fluid among chronic cannabis smokers may be expected for at least 48 hours after intake, and oral fluid samples might still be positive at one week after consumption. Negative results interspersed among positive results were found for six of the patients. … From the THC-COOH concentrations in urine, new ingestions were, however, not considered likely.”
“The study shows that frequent use of high dosages of cannabis may lead to prolonged detection times, and that positive samples can be interspersed among negative samples. These results are of great importance when THC results from oral fluid analyses are to be interpreted.”