How Cannabis Interacts With Other Drugs

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Categories : Medical cannabis

How Cannabis Interacts With Other Drugs

Knowing how cannabis interacts with other drugs is important for your wellbeing. Find out what happens when you combine cannabis with common prescription drugs and recreational substances.


Most drugs, whether prescribed pharmaceuticals or recreational substances, interact with each other to some degree. Pharmaceuticals have warnings in their product disclosure statements about how they interact with other substances. These substances can be other medications or things as innocuous as coffee or grapefruits.

Cannabis is a recreational and medical substance, interacting in a number of ways with other drugs. The reactions are generally mild, and in a number of instances, cannabis actually works together with other drugs. Sometimes, it can be the complete opposite. Rather than leaving things up to chance and ending up in the bathroom driving the porcelain bus or worse, this guide will outline how cannabis reacts with a number of common drugs.

Cannabis can have additive effects and synergistic effects when combined with other substances. An additive effect is one where the result of the combination equals the sum of their parts, 1+1=2. A synergistic effect is one where the combination is greater than the sum of their parts, 1+1=3 or more. Cannabis can increase the effectiveness of many pharmaceuticals, so close monitoring by a medical professional is advised.

Disclaimer: None of the following should be perceived as medical advice. As always, contact your health provider with any questions.


Studies have shown that marijuana users are less likely to be obese, even considering the munchies. Marijuana has the effect of making the body more efficient at carbohydrate metabolism. Tokers also have a lower risk of diabetes and lower body mass indexes than non-users. These effects are important when medication is being used to lower blood sugar levels.

The risk here is lowering blood glucose levels too much in combination with other drugs like insulin. However, evidence is inconclusive as studies have been broad epidemiological surveys that analyse general patterns within populations. Furthermore, there are few investigations into the specific interactions that THC, CBD, and terpenes contained in cannabis may have with drugs used to control blood sugar. To mitigate risks, patients using cannabis need to continually monitor their blood work in consultation with a medical professional.


The effects of hypertension or high blood pressure medication can be amplified by cannabis. Cannabinoids directly and indirectly affect the CB1 and CB2 receptors of the endocannabinoid system. This has the effect of increasing cardiac oxygen consumption while simultaneously reducing blood flow in coronary arteries. Reports of adverse effects are rare, but those taking blood pressure medication need to be aware that cannabis may compound effects.


Cannabinoids can increase the effects of drugs used for blood thinning, such as warfarin. Similar effects may be caused by drugs known for blood thinning such as ibuprofen. THC and CBD may also slow down the metabolism of these drugs, with THC displacing warfarin from protein binding sites.


Sedatives influence GABA receptors in the brain to produce a calming effect. Similarly, cannabinoids and certain terpenes have a sedative effect. Paradoxically, THC and CBD also have energising and wake-inducing effects. Much of the behaviour of cannabinoids depends on their strength, dosage, and combinations with terpenes. Cannabis can have an additive effect when combined with other sedatives. However, cannabis does not elevate blood levels or potentiate the other effects of sedative drugs.

The combination can be risky depending on the sedative and cannabis strengths. Strong indica strains are renowned for their analgesic and sedative powers. It is best to exercise caution and not mix marijuana and sedatives—just to be on the safe side.


Probably the most socially acceptable drug of them all, ironically alcohol can be fatal when mixed with other drugs. Mixing alcohol and opioids or central nervous system depressants like benzodiazepines or sleep medications is extremely dangerous. Yet many people mix alcohol and cannabis. Is this practice safe?

That depends on your point of view. Alcohol does raise THC levels in the blood, but THC does not raise alcohol levels. Research does indicate that people consume less alcohol when using cannabis. A 1985 study by NIDA examined consumption patterns in three different environments: when both alcohol and cannabis were available, when only alcohol was available, and when only cannabis was available.

• 87% of subjects consumed significantly less alcohol when both were available compared to alcohol only being available.

• 75% of subjects consumed slightly more cannabis when both were available compared to only cannabis being available.

These results compare to many people’s experiences. When both are available, more cannabis is consumed, but much less alcohol. The real danger lies in what you do when you are drinking and smoking together. Driving is far more dangerous when using cannabis and alcohol together.

Similarly, people are more likely to indulge in high-risk activities and can get severely hurt simply by doing something stupid. Also, cannabis prevents nausea and vomiting. The body is then less likely to purge toxins from the system after overindulging. This leads to a greater risk of alcohol toxicity.

How Cannabis Interacts With Other Drugs


Cytochrome P450 is an essential enzyme known to play a significant role in drug interactions within the body. Not just with cannabis, but with all drugs. Considerable clinical evidence suggests that CBD is safe and non-addictive. In many cases, it is anti-addictive and increasingly used as a supplement when trying to kick a number of harmful addictions. Sometimes, it can act synergistically with other medications either beneficially or adversely.

CBD and cytochrome P450 interact most noticeably with anti-seizure and anti-epileptic medications. A 2015 study noted that CBD increased the blood concentrations of the anticonvulsant clobazam in children. At the same time, it elevated the concentrations of the clobazam metabolite norclobazam. Clobazam can have unwanted side effects, so potentiating the medication with CBD suggests the need for smaller doses. The research found that there was a 50% reduction in seizures in all but four of the test subjects. Researchers concluded that CBD taken as a supplement to clobazam “is a safe and effective treatment for refractory epilepsy”.


The pain-relieving effects of cannabis are well-reported. Many health professionals consider it an alternative to opioid pain medication and a way to stem the tide of opioid addiction. From a toxicity and abuse standpoint, cannabis is much preferred as a frontline treatment for chronic pain.

As an adjunct to opioid therapy, cannabis has great potential. In a small 2011 study conducted by Dr Donald Abrams and his team at UC San Francisco, it was found that cannabis did not elevate opioid levels in the blood of test subjects. However, they did find that subjects reported a 27% decrease in pain levels when administered cannabis.

The conclusion was that cannabis can safely increase the effectiveness of opioid medications. This has the added benefit of treating patients with lower doses of opioids, both decreasing the risk of dependency and alleviating side effects.


Generally speaking, cannabis is safe, well-tolerated, and carries little risk when used in combination with many common drugs. However, it is not a single compound. Cannabis is a combination of dozens of cannabinoids including THC, CBD, CBN, and a vast array of terpenes, flavonoids, and more.

The combinations vary from strain to strain, and can provide an array of physiological benefits in themselves. Without further in-depth studies, drawing conclusions about the interactions with other drugs is imprecise. One thing is for sure; cannabis by itself is a therapeutic treasure chest whose benefits are only now just starting to be truly appreciated.