Cannabis can interact with many common medications through shared liver enzymes and transporters
A review of potential drug interactions found that cannabinoids can affect and be affected by the same liver enzymes and membrane transporters used by many prescription medications, warranting close monitoring in patients using both.
Quick Facts
What This Study Found
Researchers reviewed the known and potential pharmacokinetic and pharmacodynamic interactions between cannabinoids and other medications. The review identified several key interaction pathways.
Cannabinoids are metabolized by cytochrome P450 enzymes (particularly CYP3A4, CYP2C9, and CYP2C19) and UDP-glucuronosyltransferases, the same enzyme systems that process many common medications. Both THC and CBD can inhibit or induce these enzymes, potentially raising or lowering blood levels of co-administered drugs.
Additionally, cannabinoids interact with membrane transporters including P-glycoprotein, breast cancer resistance proteins, and multidrug resistance proteins. These transporters affect how drugs are absorbed and distributed throughout the body.
The review noted that while cannabinoids are generally well tolerated, bidirectional interactions should be expected, meaning cannabinoids can change how other drugs work, and other drugs can change how cannabinoids work. This is particularly important for elderly patients, people with chronic diseases, and those with kidney or liver conditions.
Key Numbers
Key CYP enzymes involved: CYP3A4, CYP2C9, CYP2C19. Key transporters: P-glycoprotein, breast cancer resistance proteins, multidrug resistance proteins. Key metabolic pathways: cytochrome P450 system, UDP-glucuronosyltransferases. Populations at highest risk: elderly, chronic disease patients, liver/kidney impairment.
How They Did This
This was a narrative review of published literature on cannabinoid pharmacokinetics, pharmacodynamics, and documented or potential drug interactions, with attention to the enzyme systems and transporters involved.
Why This Research Matters
As cannabis use expands legally and more patients combine it with prescription medications, understanding drug interactions becomes critical for safety. Many patients do not tell their doctors about cannabis use, and many doctors do not ask. This creates a blind spot where interactions could cause unexpected changes in drug efficacy or toxicity.
The Bigger Picture
Drug interaction potential is one of the most practically important aspects of cannabis pharmacology. As medical cannabis gains legal status and self-medication with commercial cannabis products grows, the healthcare system needs better tools and awareness to identify and manage these interactions, particularly for the growing population of older adults using cannabis.
What This Study Doesn't Tell Us
Many potential interactions identified in this review are theoretical, based on shared enzyme pathways rather than documented clinical events. In vitro enzyme inhibition data may not translate directly to clinically meaningful interactions at typical cannabis doses. The review does not quantify the likelihood or severity of specific interactions.
Questions This Raises
- ?Which specific drug-cannabis interactions are clinically significant at typical use levels?
- ?Should cannabis users on multiple medications undergo therapeutic drug monitoring?
- ?How should pharmacists counsel patients about cannabis-medication interactions?
Trust & Context
- Key Stat:
- Cannabinoids share metabolic pathways (CYP3A4, CYP2C9) with many common drugs
- Evidence Grade:
- This is a narrative review synthesizing pharmacokinetic and pharmacodynamic data, providing moderate-level guidance based on known metabolic pathways.
- Study Age:
- Published in 2018. Drug interaction research for cannabis has continued to evolve with more clinical data.
- Original Title:
- Medicinal Cannabis-Potential Drug Interactions.
- Published In:
- Medicines (Basel, Switzerland), 6(1) (2018)
- Authors:
- Alsherbiny, Muhammad A, Li, Chun Guang
- Database ID:
- RTHC-01573
Evidence Hierarchy
Summarizes existing research on a topic.
What do these levels mean? →Frequently Asked Questions
Can cannabis change how my medications work?
Yes, potentially. Cannabis compounds are processed by the same liver enzymes (like CYP3A4) that metabolize many prescription drugs. This means cannabis could raise or lower blood levels of other medications. The risk is highest for people taking multiple medications, elderly patients, and those with liver or kidney conditions.
Should I tell my doctor I use cannabis?
This review strongly supports disclosing cannabis use to healthcare providers, particularly if you take prescription medications. The bidirectional nature of the interactions means both your cannabis effects and your medication effects could be altered.
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Cite This Study
https://rethinkthc.com/research/RTHC-01573APA
Alsherbiny, Muhammad A; Li, Chun Guang. (2018). Medicinal Cannabis-Potential Drug Interactions.. Medicines (Basel, Switzerland), 6(1). https://doi.org/10.3390/medicines6010003
MLA
Alsherbiny, Muhammad A, et al. "Medicinal Cannabis-Potential Drug Interactions.." Medicines (Basel, 2018. https://doi.org/10.3390/medicines6010003
RethinkTHC
RethinkTHC Research Database. "Medicinal Cannabis-Potential Drug Interactions." RTHC-01573. Retrieved from https://rethinkthc.com/research/alsherbiny-2018-medicinal-cannabispotential-drug-interactions
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.