Cannabis Can Interfere with Your Medication, Leading to Potential Harm

Key Takeaways:

  • Cannabis, including substances like THC and CBD, can interfere with the metabolism of other medications, as they are processed by similar groups of enzymes in the body.
  • Potential risks include amplification of certain prescription drugs or causing others to pass through the system so quickly that they become ineffective.
  • Some medications that could be affected by cannabis usage include blood-thinners like warfarin, breast cancer medications like tamoxifen, and over-the-counter painkillers like acetaminophen and ibuprofen.
  • Recent lab studies reveal that all three major cannabis compounds, but especially CBD, impede key enzymes in the liver and kidney that are responsible for drug and toxin clearance.
  • Clinical trials are needed to establish the full magnitude of cannabis’s effects on other drugs, and it’s crucial for individuals to discuss their cannabis product usage with their healthcare providers.

It’s not uncommon for people to use marijuana or cannabidiol (CBD) as pain relief or a sleep aid. However, recent research suggests this habit could adversely interact with your other medical treatments.

This is because the body uses the same groups of enzymes to process these substances, the researchers explained. The active components in cannabis — THC, CBD, and cannabinol (CBN) — are broken down by at least two groups of enzymes that also help process and eliminate most commonly used prescription drugs, according to the researchers.

Potential Risks

This means that cannabis could potentially amplify the effects of some prescription drugs, or prompt others to pass through your system so quickly they become ineffective. These findings were presented by lead researcher Philip Lazarus, who teaches pharmaceutical sciences at Washington State University in Spokane.

Significant Inhibitions

“We saw some significant inhibitions,” Lazarus mentioned, referring to the impact of cannabis components on these enzymes. “The concentrations we see in the lab are likely an indicator that there is at least some hindrance of these enzymes in real-time.”

Some of the drugs that might be impacted by cannabis usage include blood-thinner warfarin, breast cancer medication tamoxifen, and painkillers such as acetaminophen (Tylenol) and ibuprofen (Motrin).

Lab Reports and Revelations

In two lab studies recently published in the journal Drug Metabolism and Disposition, Lazarus acted as senior author. The first study focused on a group of enzymes called cytochrome P450s (CYPs) while the second looked into the enzyme group called UDP-glucuronosyltransferases (UGTs). CYPs are involved in breaking down THC and CBD at the first stage, whereas UGTs participate in the later stages.

Implications for Metabolism

THC and CBD remain in your body for about half an hour before these enzymes break them down. However, the resulting chemicals from the process can remain in your body for up to two weeks, the researchers stated. The researchers conducted a lab study examining how the active components in cannabis could disrupt these enzymes’ ability to metabolize other medications.

The Findings

The researchers discovered that THC metabolites inhibited key enzymes, including those playing important roles in liver processes. All three cannabis compounds, but especially CBD, impeded the primary UGT enzymes in the liver. CBD was also found to obstruct enzymes responsible for most UGT activity in the kidney, which assists in toxin and drug clearance.

Interactions are Real

“It’s a good reminder that these interactions are real,” said Ed Bednarczyk, a clinical associate professor of pharmacy practice at the University presented a first-time demonstration of the potential effects of cannabis on UGT enzymes. This study also provides new insights into the way cannabis impacts CYP enzymes.

Ongoing Debate

Paul Armentano, a prominent advocate for the reform of cannabis laws, recognizes that the long-standing knowledge of potential drug interactions with cannabis suggests a need for further exploration.

While recreational or medicinal consumption of cannabis compounds has been a common practice for centuries, Armentano points to the potential lack of empirical evidence documenting significant contraindications in this increasingly widespread demographic. Despite potential enzyme inhibitions, Lazarus acknowledges that occasional cannabis use likely doesn’t impact daily metabolism substantially.

Cautionary Tales

Challenges arise when mixing regular cannabis use with other drugs. One noteworthy example is the potent blood thinner, warfarin. Previous case studies have indicated potentially lethal risks when combining warfarin with CBD.

The hormones of tamoxifen, a therapy drug used for treating breast cancer, presents another risk. Tamoxifen needs to be converted into a chemical called endoxifen by the body for it to work. If cannabis interferes with this process, it could lead to inefficient treatment for the patient.

A third concern is the potential interaction between cannabis and over-the-counter pain relievers. “It would probably lead to toxicity because you’re slowing down its metabolism, which means you’re not excreting the stuff and you have more of it sitting in your body,” Lazarus cautioned.

Future Steps

Lazarus noted that clinical trials will be essential to establish the real-world effects of cannabis on other drugs. Until then, it’s crucial for individuals to discuss their cannabis product usage with their healthcare providers to ensure they’re not putting their health at risk.

More Information

The Mayo Clinic provides additional insights on possible drug interactions with cannabis.


Greetings from the trails and tracks! I'm Tim, but most folks know me as TJ. I've spent the last 5 years diving deep into the world of content writing, with a particular penchant for nutrition and the intricate science behind it. Every bite we take, every nutrient we consume, tells a unique story – and I'm here to unravel it for you.Beyond my keyboard, you'll often find me on a winding hiking trail or pushing my limits on a long-distance run. These pursuits not only keep me fit but constantly remind me of the vital role nutrition plays in fueling our passions and adventures.Through my writings, I aim to bridge the gap between complex nutritional science and everyday eating habits. Whether you're looking for the latest research updates, practical diet tips, or stories from the running track, I'm committed to serving you content that's as engaging as it is enlightening.So, lace up your shoes, grab a healthy snack, and join me in this exploration of food, science, and the great outdoors. Together, we'll journey towards better health and incredible experiences!
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