# Cannabinoid Drug Interactions: Clinical Evidence Review > **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637) > **Publisher:** CED Clinic (https://cedclinic.com) > **Canonical URL:** https://cedclinic.com/cannabinoid-drug-interactions/ > **Published:** 2026-04-25T14:02:03-04:00 | **Last Modified / Clinically Audited:** 2026-09-28T10:57:46-04:00 > **Clinical Summary:** Explore clinical evidence on cannabinoid drug interactions, focusing on safety and effects with medications metabolized by cytochrome P450 enzymes. --- #### Clinical Takeaway CBD commonly inhibits cytochrome P450 enzymes at high doses, potentially increasing levels of medications metabolized through CYP3A4, CYP2C19, and CYP2C9, though clinical significance varies by individual patient factors and CBD dosing. In cancer patients on multiple medications, monitoring for altered drug efficacy or toxicity is warranted when combining CBD with certain opioids, anticoagulants, and antiarrhythmics. Current evidence suggests dose-dependent interactions are possible but serious adverse events remain uncommon in controlled clinical settings. ### #19 Drug Interactions in People on Cannabidiol: Is There Cause for Concern? **Citation:** Downs Georgia et al. *[Drug Interactions](https://cedclinic.com/cannabis-liver-interactions-study-insights/) in People on Cannabidiol: Is There Cause for Concern?* Cannabis and [cannabinoid research](https://cedclinic.com/cannabinoids-in-reward-processing-pain-perception/). 2026. PMID: 39539239. **Study type:** Journal Article, Randomized Controlled Trial  |  **Topic area:** Cannabidiol  |  **CED Score:** 10 Design: 5 Journal: 1 N: 0 Recency: 3 Pop: 2 Human: 1 Risk: -2 **Quality Gate Alerts:** - Preclinical only **Abstract:** INTRODUCTION: Cannabidiol (CBD) exhibits multiple therapeutic properties, but its use in advanced cancer patients raises concerns about potential drug-drug interactions (DDIs) due to polypharmacy. This study aims to look for evidence of DDIs between concomitant medications and CBD oil in a randomized placebo-controlled trial of CBD oil for symptom control (MedCan-1 parent study). MATERIALS AND METHODS: Surrogate measures were used to identify possible drug interactions: (1) the maximum mL of oil self-selected by patients in CBD or placebo groups in relation to opioids, specific drug groups, or individual agents; (2) the occurrence of any new or worse adverse effect in relation to the study arm and the concomitant medication classes/medications of interest. RESULTS: The dose of CBD self-selected by participants was not related to opioid use or medications, including benzodiazepines and antipsychotics. The likelihood of developing an adverse effect while on study or when taking specific medications was not increased by CBD. Participants on paracetamol tolerated a higher dose of CBD. DISCUSSION: Concerns regarding the development of clinically significant drug interactions when taking CBD in the context of anti-cancer and other concomitant medications at least in the short term may be unfounded.  |  [View on PubMed ↗](https://pubmed.ncbi.nlm.nih.gov/39539239/)[DOI ↗](https://doi.org/10.1089/can.2024.0041) [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. 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[Read More](https://cedclinic.com/cannabinoid-drug-interactions-clinical-evidence/) [Medical Marijuana Helps People Stop Using Opioids, Sleeping Aids And Other Prescription …](https://cedclinic.com/medical-cannabis-prescription-patterns-reduce-opioid-use/) Explore how [medical marijuana](https://cedclinic.com/cannabis-cardiovascular-risk-impact/) may reduce reliance on opioids and other prescription drugs, highlighting clinical outcomes. [Learn More](https://cedclinic.com/medical-cannabis-prescription-patterns-reduce-opioid-use/) [German Medical Cannabis Patients Report Reduced Prescription Drug Use, Survey Finds](https://cedclinic.com/german-medical-cannabis-patients-prescription-reduction-survey/) Survey findings from German [medical cannabis](https://cedclinic.com/therapeutic-benefits-of-thc/) patients showing decreased prescription drug use and implications for drug interactions. [Discover Insights](https://cedclinic.com/german-medical-cannabis-patients-prescription-reduction-survey/) Have thoughts on this? 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