Are There Risks of Cannabis Interacting With Other Medications?

As more people turn to cannabis for relief, whether it’s to ease anxiety, manage chronic pain, or simply sleep better, one important question keeps coming up: “If I’m taking other medications, is cannabis safe?”

It’s a crucial question. And one that deserves a thoughtful answer.

Because while cannabis is one of nature’s most remarkable healers, it’s not completely without risk, especially when it comes to how it might interact with pharmaceutical drugs.

Today, we want to walk you through what we know about cannabis and medication interactions so you can make informed, confident choices about your health.

Cannabis: a complex, natural medicine

First things first: cannabis isn’t a one-size-fits-all medicine. 

It contains hundreds of active compounds – cannabinoids like THC and CBD, terpenes, flavonoids – all working together to interact with your body’s endocannabinoid system (ECS).

This complexity is part of what makes cannabis so powerful. But it also means it can affect other processes in your body, including how you metabolise certain medications.

The key player here? The cytochrome P450 enzyme system, a group of enzymes in your liver that break down many of the drugs you take.

Both THC and CBD can temporarily interfere with these enzymes. Meaning they can either slow down or speed up the metabolism of other medications, leading to higher or lower levels of those drugs in your system than intended.

In some cases, this could amplify side effects. In others, it could reduce a medication’s effectiveness.

Which medications are most likely to interact with cannabis?

While research is still ongoing, we have some good insights into the main categories of drugs where caution is wise:

• Blood thinners (like warfarin): Cannabis, particularly CBD, can increase blood levels of these drugs, potentially raising the risk of bleeding.
  
• Sedatives (like benzodiazepines, opioids, and some antihistamines): Combining these with cannabis can enhance drowsiness or sedation, sometimes dangerously.
  
• Antidepressants and antipsychotics: Cannabis may either heighten or lessen the effects, depending on the drug and dose.
  
• Antiepileptics: CBD can influence the blood levels of some epilepsy medications, like clobazam.
  
• Immunosuppressants: For those who’ve had organ transplants or have autoimmune conditions, cannabis could theoretically affect medication levels.
  
• Heart medications (like calcium channel blockers and beta-blockers): There’s some evidence that cannabis could alter how these are processed, too.

This doesn’t mean if you’re on these medications you can’t use cannabis, but it does mean a personalised, cautious approach is necessary.

Factors that influence cannabis-drug interactions

Not everyone will experience interactions in the same way. Several factors play a role, including:

• Your dose of cannabis (higher doses = higher likelihood of interactions)
  
• How you consume it (inhaled vs. edible vs. topical — each has different absorption rates)
  
• Your individual metabolism and genetics
  
• Your liver function
  
• Which cannabinoid profile you’re using (CBD and THC are the main ones impacting P450 enzymes, but others could have effects too)
  

This highlights a point we always come back to: Self-awareness and gradual experimentation are key.

What does the science say?

A growing number of studies, especially those looking at CBD, have confirmed its ability to affect drug metabolism.

For example, a study published in Epilepsia found that high doses of CBD increased blood levels of clobazam (an anti-epileptic drug), requiring dosage adjustments. Other clinical studies have seen changes in warfarin levels when CBD was introduced.

That said, the vast majority of cannabis-drug interactions reported so far are minor, and often manageable with slight adjustments and good monitoring.

It’s also worth noting: real-world data from medical cannabis patients shows that most use cannabis alongside other medications without major issues, provided there’s open communication with healthcare providers.

How to safely use cannabis if you’re taking other medications

Here’s the best-practice guidance we give anyone considering cannabis while on meds:

1. Start low, go slow: Especially if you’re on medications that could be affected, begin with the smallest effective dose of cannabis and increase gradually if needed.
   
2. Track everything: Keep a simple journal noting your cannabis dose, timing, how you feel, and any medication side effects. Patterns will quickly become clear.
   
3. Communicate with your healthcare provider: Ideally, work with a doctor who understands cannabis therapeutics. At the very least, be upfront with your GP or prescribing doctor.
   
4. Focus on balance, not extremes: High-dose THC products, while sometimes necessary, carry more risk for interactions. Balanced THC:CBD formulas or CBD-rich products may offer therapeutic benefits with lower risk.
   
5. Prioritise lifestyle foundations: Remember, cannabis is a tool, not a crutch. It works best when combined with lifestyle measures like nutrition, exercise, sunlight, sleep, and stress management.
   

A quick word on recreational use

Even if you’re not using cannabis “medicinally”, if you’re mixing it with alcohol, opioids, or prescription sedatives recreationally, the risk of sedation, impaired thinking, and accidents increases.

Respect the plant. Respect your body.

Conclusion

At the end of the day, cannabis offers incredible potential to support healing, but, like any powerful tool, it deserves to be used wisely.

If you want to stay informed, empowered, and at the cutting edge of cannabis and natural health research, join our community.

👉 Sign up to our newsletter below, and get honest, science-backed insights delivered straight to your inbox.