Vaporized CBD reached peak blood concentrations 8-12 times higher than oral CBD at the same 100 mg dose, and neither route produced detectable THC or its metabolites.
CBD users, clinicians, pharmacologists, and anyone concerned about CBD and drug testing.
Vaporized CBD peak: 171 ng/mL vs. oral: 14 ng/mL
What the researchers found
Mean peak CBD blood concentration was 171.1 ng/mL for vaporized CBD-dominant cannabis, 104.6 ng/mL for vaporized pure CBD, and only 13.7 ng/mL for oral CBD. Among oral formulations, Epidiolex produced the highest peak (20.5 ng/mL) vs. capsule (17.8 ng/mL) and syrup (2.8 ng/mL). Pure CBD by either route did not produce detectable THC or THC-COOH in blood.
Why it matters
Massive differences in bioavailability between oral and vaporized CBD have direct implications for dosing, product selection, and drug testing. The confirmation that pure CBD does not convert to THC addresses a common concern.
The numbers in context
Peak CBD: vaporized cannabis 171.1 ng/mL (range 40-665), vaporized pure CBD 104.6 ng/mL (range 19-312), oral CBD 13.7 ng/mL (range 0-50). THC detected in 12/18 after vaporized CBD-dominant cannabis but in 0/18 after pure CBD products.
How the study worked
Within-subject, double-blind, double-dummy, placebo-controlled study in 18 adults. Each participant received 100 mg CBD via oral, vaporized, and vaporized CBD-dominant cannabis (10.5% CBD/0.39% THC) routes, plus placebo. Blood and oral fluid were collected for 57-58 hours post-dose.
What this study cannot tell us
Small sample size (n=18). Single-dose study. Limited to three oral formulations. Fasting condition only tested in 6 participants. May not reflect real-world use patterns with repeated dosing.
How to read the evidence
Well-designed within-subject RCT with multiple comparisons, limited by small sample size.
When this study was published
Published in 2022.
The bigger picture
These pharmacokinetic differences explain why vaporized and oral CBD may produce different clinical effects and why research findings from one route may not apply to another. The absence of THC conversion is reassuring for workplace drug testing.
Questions still open
- Do the higher blood levels from vaporization translate to greater therapeutic effects? Would repeated dosing change the pharmacokinetic profile? Should CBD dosing recommendations differ by route?
Common questions
Will taking CBD cause a positive drug test for THC?
Why does vaporized CBD produce higher blood levels than oral CBD?
Read the original research
Pharmacokinetic Profile of ∆9-Tetrahydrocannabinol, Cannabidiol and Metabolites in Blood following Vaporization and Oral Ingestion of Cannabidiol Products.
Journal of analytical toxicology, 46(6), 583-591
Citation
Bergeria, Cecilia L; Spindle, Tory R; Cone, Edward J; Sholler, Dennis; Goffi, Elia; Mitchell, John M; Winecker, Ruth E; Bigelow, George E; Flegel, Ronald; Vandrey, Ryan. (2022). Pharmacokinetic Profile of ∆9-Tetrahydrocannabinol, Cannabidiol and Metabolites in Blood following Vaporization and Oral Ingestion of Cannabidiol Products.. Journal of analytical toxicology, 46(6), 583-591. https://doi.org/10.1093/jat/bkab124
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