Delta-8-THC Can Cause Significant Drug Interactions by Inhibiting Liver Enzymes
Delta-8-THC and its active metabolite significantly inhibit CYP2C9 and CYP3A4 liver enzymes, potentially causing clinically relevant drug interactions — especially with oral consumption.
Quick Facts
What This Study Found
Delta-8-THC competitively inhibited CYP2C9-mediated warfarin metabolism and non-competitively inhibited CYP2C9 and CYP3A4 metabolism of other substrates. Static modeling predicted clinically relevant interactions, particularly with oral delta-8-THC. The inactive metabolite (11-nor-delta-8-THC-9-carboxylic acid) showed no inhibition.
Key Numbers
Significant inhibition of CYP2C9 and CYP3A4. Competitive inhibition of CYP2C9-warfarin. Non-competitive inhibition of CYP2C9-diclofenac and CYP3A4-midazolam. 11-nor-delta-8-THC-9-carboxylic acid: no inhibition.
How They Did This
In vitro enzyme inhibition study using recombinant P450-overexpressing microsomes and pooled human liver microsomes, with Lineweaver-Burk kinetic analysis and static drug interaction modeling.
Why This Research Matters
Delta-8-THC is widely available in states where delta-9-THC is restricted, but its drug interaction potential was unknown. This study reveals significant risks for people taking common medications metabolized by CYP2C9 (like warfarin) and CYP3A4.
The Bigger Picture
The delta-8-THC market has exploded in regulatory grey areas. This is the first study to characterize its drug interaction potential, revealing risks that consumers and healthcare providers need to know about.
What This Study Doesn't Tell Us
In vitro study — actual clinical drug interactions depend on achievable tissue concentrations. Static modeling may over- or underpredict real-world interactions. Individual variation in enzyme activity not captured.
Questions This Raises
- ?Should delta-8-THC products carry drug interaction warnings?
- ?Are people on blood thinners (warfarin) at particular risk from delta-8-THC use?
Trust & Context
- Key Stat:
- Evidence Grade:
- Rigorous in vitro pharmacology with appropriate kinetic analysis and modeling — strong mechanistic evidence though clinical validation needed.
- Study Age:
- First-ever characterization of delta-8-THC drug interaction potential, addressing a critical safety gap in the rapidly growing delta-8 market.
- Original Title:
- Inhibitory effects of Δ8-tetrahydrocannabinol on major hepatic cytochrome P450 enzymes and implications for drug disposition.
- Published In:
- Drug metabolism and disposition: the biological fate of chemicals, 53(9), 100122 (2025)
- Authors:
- Zhao, Mengqi(2), Coates, Shelby(2), Bardhi, Keti(2), Lazarus, Philip
- Database ID:
- RTHC-08039
Evidence Hierarchy
Frequently Asked Questions
Can delta-8-THC interact with medications?
Yes — this study shows it significantly inhibits two major liver enzymes (CYP2C9 and CYP3A4) that metabolize many common drugs, including warfarin, diclofenac, and midazolam.
Is oral delta-8-THC riskier for drug interactions than smoking?
Yes — the modeling predicted higher interaction risk with oral consumption because it results in higher liver concentrations of delta-8-THC than inhaled forms.
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Cite This Study
https://rethinkthc.com/research/RTHC-08039APA
Zhao, Mengqi; Coates, Shelby; Bardhi, Keti; Lazarus, Philip. (2025). Inhibitory effects of Δ8-tetrahydrocannabinol on major hepatic cytochrome P450 enzymes and implications for drug disposition.. Drug metabolism and disposition: the biological fate of chemicals, 53(9), 100122. https://doi.org/10.1016/j.dmd.2025.100122
MLA
Zhao, Mengqi, et al. "Inhibitory effects of Δ8-tetrahydrocannabinol on major hepatic cytochrome P450 enzymes and implications for drug disposition.." Drug metabolism and disposition: the biological fate of chemicals, 2025. https://doi.org/10.1016/j.dmd.2025.100122
RethinkTHC
RethinkTHC Research Database. "Inhibitory effects of Δ8-tetrahydrocannabinol on major hepat..." RTHC-08039. Retrieved from https://rethinkthc.com/research/zhao-2025-inhibitory-effects-of-8tetrahydrocannabinol
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.