# Plasma cannabinoid pharmacokinetics following the inhalation of vaporised cannabis with and without cannabidiol. > **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637) > **Publisher:** CED Clinic (https://cedclinic.com) > **Canonical URL:** https://cedclinic.com/cbd-effects-thc-plasma-concentrations-vaporized-cannabis-study/ > **Published:** 2026-04-27T16:23:33-04:00 | **Last Modified / Clinically Audited:** 2026-09-28T17:17:14-04:00 > **Clinical Summary:** New research shows CBD does not significantly alter THC plasma concentrations when cannabis is vaporized, with similar pharmacokinetics in adolescents and adult --- CED Clinical Relevance  #100High Clinical Relevance Evidence Brief | CED ClinicCBD co-administration does not significantly alter THC plasma concentrations when cannabis is vaporized and inhaled in controlled conditions. ThcCbdPharmacokineticsVaporization[Drug Interactions](https://cedclinic.com/cannabis-liver-interactions-study-insights/) CBD co-administration does not significantly alter THC plasma concentrations when cannabis is vaporized and inhaled in controlled conditions. What This Study Teaches Us This controlled study provides evidence that CBD does not meaningfully interfere with THC absorption or metabolism when cannabis is vaporized. The crossover design with weight-adjusted dosing offers more precision than previous observational studies that showed mixed results. Why This Matters Patients and clinicians often assume CBD will reduce THC effects through pharmacokinetic interference, but this data suggests the interaction may be primarily pharmacodynamic. This informs dosing decisions when patients use THC:CBD combination products. Study Snapshot Study Type Randomized Controlled Trial Population 48 participants aged 16-17 years and 26-29 years Intervention Vaporized THC-alone (8mg THC/75kg) vs THC+CBD (8mg THC + 24mg CBD/75kg) Comparator Placebo control Primary Outcome Plasma THC and metabolite concentrations Key Finding CBD presence did not significantly alter THC pharmacokinetics Journal Drug and Alcohol Dependence Year 2024 Clinical Bottom Line When counseling patients using vaporized cannabis products containing both THC and CBD, clinicians should not expect CBD to significantly reduce THC blood levels. Any modulating effects of CBD on THC are likely occurring at the receptor level rather than through altered absorption or metabolism. What This Paper Does Not Show The abstract does not provide the actual plasma concentration values, statistical significance data, or details about the metabolite profiles. It also does not address whether age differences in pharmacokinetics were observed, despite this being a stated study aim. Where This Paper Deserves Skepticism The study used specific weight-adjusted doses that may not reflect real-world usage patterns. Vaporization represents only one delivery method, and results may not apply to other consumption routes like edibles or smoking. Dr. Caplan's Take I’m surprised CBD didn’t alter THC levels more substantially, given theoretical enzyme competition. This reinforces my clinical observation that CBD’s therapeutic effects alongside THC are likely receptor-mediated rather than simply reducing THC exposure. What a Careful Reader Should Take Away This well-controlled study challenges assumptions about CBD reducing THC bioavailability through pharmacokinetic mechanisms. However, the clinical implications remain limited without seeing the actual concentration data and effect sizes from the full publication. Join the Conversation Have a question about how this applies to your situation? [Ask Dr. Caplan →](https://benjamincaplan.com/ask-dr-caplan) Want to discuss this topic with other patients and caregivers? [Join the forum discussion →](https://cedclinic.com/interact/discussion-forums/forum/cannabis-industry/) Have thoughts on this? Share it: [X Share on X](https://twitter.com/intent/tweet?text=Just%20read%20this%20on%20CEDclinic.com%3A%20Plasma%20cannabinoid%20pharmacokinetics%20following%20the%20inhalation%20of%20vaporised%20cannabis%20with%20and%20without%20...%20%40drcaplan&url=https%3A%2F%2Fcedclinic.com%2Fcbd-effects-thc-plasma-concentrations-vaporized-cannabis-study%2F)[in Share on LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fcedclinic.com%2Fcbd-effects-thc-plasma-concentrations-vaporized-cannabis-study%2F)[🦅 Share on BlueSky](https://bsky.app/intent/compose?text=Just%20read%20this%3A%20Plasma%20cannabinoid%20pharmacokinetics%20following%20the%20inhalation%20of%20vaporised%20cannabis%20with%20and%20without%20...%20via%20%40drcaplan.bsky.social%20https%3A%2F%2Fcedclinic.com%2Fcbd-effects-thc-plasma-concentrations-vaporized-cannabis-study%2F)[📷 Follow on Instagram](https://www.instagram.com/drbenjamincaplan)[📝 Read more on Substack](https://doctorapprovedcannabis.substack.com/)[🔔 Subscribe via RSS](https://cedclinic.com/feed/) Table of Contents - [FAQ](#FAQ)[Does CBD affect how THC is absorbed and processed in the body when vaping cannabis?](#Does_CBD_affect_how_THC_is_absorbed_and_processed_in_the_body_when_vaping_cannabis) - [Are there differences in cannabis pharmacokinetics between adolescents and adults?](#Are_there_differences_in_cannabis_pharmacokinetics_between_adolescents_and_adults) - [What dosages were used in this study and how do they relate to clinical practice?](#What_dosages_were_used_in_this_study_and_how_do_they_relate_to_clinical_practice) - [How quickly does vaporized cannabis reach peak blood levels?](#How_quickly_does_vaporized_cannabis_reach_peak_blood_levels) - [Why is this pharmacokinetic research clinically important for cannabis medicine?](#Why_is_this_pharmacokinetic_research_clinically_important_for_cannabis_medicine) - [Related](#Related) ## FAQ #### Does CBD affect how THC is absorbed and processed in the body when vaping cannabis? Based on this controlled study, CBD co-administration does not significantly alter THC plasma concentrations when cannabis is vaporized and inhaled. This finding suggests that CBD does not meaningfully interfere with THC absorption or metabolism through inhalation routes. #### Are there differences in cannabis pharmacokinetics between adolescents and adults? This study specifically examined cannabinoid plasma pharmacokinetics in both adolescents (16-17 years) and adults (26-29 years) to understand age-related differences. The research provides important data on how age may moderate cannabis processing, though specific results would require reviewing the complete study findings. #### What dosages were used in this study and how do they relate to clinical practice? The study used weight-adjusted dosing of 8mg THC alone or combined with 24mg CBD per 75kg body weight via vaporization. These controlled dosages provide clinically relevant pharmacokinetic data for [medical cannabis](https://cedclinic.com/therapeutic-benefits-of-thc/) prescribing and [patient counseling](https://cedclinic.com/stroke-risk-assessment-substance-use/) regarding vaporized cannabis products. #### How quickly does vaporized cannabis reach peak blood levels? Blood samples were collected at 20, 30, and 160 minutes post-inhalation to track cannabinoid absorption patterns. This timeframe captures the rapid onset characteristic of inhaled cannabis, providing clinicians with evidence-based timing for peak plasma concentrations and duration of measurable levels. #### Why is this pharmacokinetic research clinically important for cannabis medicine? Understanding how CBD affects THC pharmacokinetics is crucial for optimizing [medical cannabis](https://cedclinic.com/therapeutic-benefits-of-thc/) formulations and predicting [drug interactions](https://cedclinic.com/cannabis-liver-interactions-study-insights/). This randomized, double-blind, placebo-controlled study provides high-quality evidence to guide [clinical decision-making](https://cedclinic.com/cannabinoids-mental-health-systematic-review-evidence-insights/) regarding cannabis product selection and dosing strategies. [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Physician-Led, Whole-Person Care A doctor who takes the time to truly understand you. Personal care that starts with listening and is guided by experience and ingenuity. Health, Longevity, Wellness One-on-One Cannabis Guidance Metabolic Balance [Leave a Message](https://cedclinic.com/contact/) [Metabolic Care](https://cedclinic.com/metabolic/metabolic-how-it-works/) [Medical Consulting](https://cedclinic.com/book/) [Cannabis Care](https://cedclinic.com/book/) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) ### Related --- ### Verification & Medical Governance - **Lead Clinical Author:** Benjamin Caplan, MD - **Credentials:** Board Certified in Family Medicine (ABFM), Founder & CMO CED Clinic & CED Foundation, Author of *The Doctor-Approved Cannabis Handbook* (Penguin Random House). - **Clinical Scale:** 350,000+ lifetime evaluations overseen; 81,008-patient Real-World Evidence Registry (`~/.ced_rwe_vault.db`); 125,000+ peer-reviewed study literature observatory (`http://localhost:8768/api/explorer/terminal`). - **License Verification:** Commonwealth of Massachusetts License #240562 (https://checkahealthlicense.mass.gov/). - **NPI Registry:** 1962722637 (https://npiregistry.cms.hhs.gov/provider-view/1962722637). - **Ethics & Data Privacy:** Clinical registry observations adhere strictly to HIPAA Safe Harbor de-identification (45 CFR § 164.514(b)) and criteria for secondary research exemption under 45 CFR § 46.104(d)(4).