More and more commonly, people with a positive urine test for THC are insisting they only used cannabidiol (CBD). Someone ingesting only CBD should not have a positive urine sample for THC.
Individuals often assume they are taking only CBD because the product label says “CBD”. However, they may be taking hemp oil, which can contain up to 0.3% THC, by law. When someone ingests hemp oil, they may have a positive urine test for THC, even though they only ingested a small amount of THC, because urine tests are designed to detect and measure very small amounts of THC. Every time an unreliable company mis-labels its products as “CBD”, when it contains other products, including THC, that company puts unsuspecting individuals at risk for having a positive THC urine test.
Some scientists have a theory that under an unusual and specific circumstance, it may be possible for a person ingesting only CBD to produce a positive THC urine test, but this possibility is not yet proven. To understand the possible positive urine test, it is necessary to review THC urine testing.
Urine is not tested for Delta9-THC, the form of THC that makes people high. Urine is tested for a metabolite of THC, 11-nor-delta9-THC, because this metabolite stays in the body at detectable levels for much longer than Delta9-THC. After someone ingests Delta9-THC, it is metabolized in the liver to 11-nor-delta9-THC. A “positive THC urine test” means the test found levels of 11-nor-delta9-THC. However, for simplicity, we always say we are testing for THC and this convention will be used for the remainder of this paper.
There are two types of tests that are used to assess cannabis use: 1) Immunoassay test and 2) GC-MS test. The immunoassay is used as a screening test because it is easy and cheap. For example, dipsticks are a form of immunoassay. However, immunoassays for THC produce a high rate of false positives (the test is positive even when THC has not been used) but not many false negatives (the test is negative even when THC has been used). Every time the immunoassay is positive, it should be followed up with GC-MS as a confirmatory test. The confirmatory GC-MS test is extremely specific and produces almost no false positives. However, the GC-MS is both time consuming and expensive. Almost all law enforcement and major companies use immunoassay for screening and follow-up with GC-MS confirmatory testing.
Generally, CBD is not converted into THC in the human body. However, there is scientific debate as to whether CBD can be converted to THC in the stomach.1-5 This discussion started when a study using simulated gastric juice found that synthetic CBD could be converted to delta9-THC and other cannabinoids.1 In contrast, studies in humans have not found any delta-9 THC in the blood stream nor any clinical evidence of any form of THC.2-4
However, one of these studies did find a slight increase in nor-11-delta9-THC three hours after ingestion of high doses of CBD (>600mg).2 It is unlikely that such low blood levels of nor-11-delta9-THC would produce enough 11-nor-delta9-THC in urine to return a positive urine test. The only situation where a positive result might exist would be when very sensitive urine testing limits (10 nanograms/ml) were used, the urine was obtained at a very specific time after ingestion, the urine was very concentrated, and the individual was orally ingesting very high quantities of CBD (>600mg/day).5 Ingestion of CBD via any other means than oral have never been found to be converted to THC or any of its metabolites.
To definitively answer this debate a study examining the relationship between urine THC testing and CBD ingestion would need to be performed. Such a study has never been reported in the literature.
Positive screening tests for THC can occur in individuals that are consuming CBD because false positives are common with the immunoassay screening kits. However, a confirmatory test using GC-MS should not be positive. When it does occur, most of the time, the individual will be consuming a product that contains some amount of THC, either knowingly or unknowingly. There is a rare theoretical possibility that an individual who is taking very large amounts of CBD orally (>600mg/day) may have a positive THC urine test. However, such a case has never been documented.
If someone desires to consume CBD and wants to avoid a positive urine THC, they need to obtain their CBD from a reliable source that tests its products for the presence (or absence, in this case) of THC. CBD American Shaman produces a THC-free CBD products specifically for this purpose. They test each product in their lab for the absence of TCH before it is released. Other companies may produce THC-free CBD products that can also be used, but I am not familiar with their internal processes for manufacturing and testing to be able to recommend them at this time. At this point, there have been no confirmed reports of positive THC urine tests from individuals that are using CBD American Shaman THC-free products only.
1. Merrick J, etal. Identiﬁcation of psychoactive degradants of cannabidiol in simulated gastric and physiological ﬂuid, Cannabis and Cannabinoid Research 1:1:102–112.
2. Consroe P, etal. Assay of plasma cannabidiol by capillary gas chromatography/ion trap mass spectroscopy following high-dose repeated daily oral administration in humans. Pharmacol Biochem Behav. 1991 Nov;40(3):517-22.
3. Martin-Santos R, etal. Acute effects of a single, oral dose of d9-tetrahydrocannabinol (THC) and cannabidiol (CBD) administration in healthy volunteers. Curr Pharm Des. 2012;18(32):4966-79.
4. Grotenhermen F, etal. Even high doses of oral cannabidiol do not cause THC-like effects in humans: Comment on Merrick et al. Cannabis and Cannabinoid Research 2016;1(1):102-112; DOI:10.1089/can.2015.004
5. Bonn-Miller M, etal. Conversion of cannabidiol following oral administration: Authors’ response to Grotenhermen et al. DOI: 10.1090/can.20160036. Cann Canna Res 2017;2(1):5-7.