How Does Cannabis Interact With Other Drugs?

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How Does Cannabis Interact With Other Drugs?

Post by notsofasteddie »

How Does Cannabis Interact With Other Drugs?

Jeremy Kossen


Virtually all chemical compounds, from over-the-counter drugs and prescription pharmaceuticals to illicit substances, interact with other compounds. There are, for example, 82 identified drug interactions with caffeine (of which 25 are classified as moderately severe to severe). Even seemingly benign substances, like grapefruit, are known to interact with many prescription drugs. When it comes to cannabis, most potential interactions that have been identified are relatively mild. And, in fact, some drugs seem to work together with cannabis favorably.

RELATED STORY Does Cannabis Interact with Antidepressants?

But, before we dive deep on some of the most common drugs people combine with cannabis, it’s important to understand the difference between an “additive” and “synergistic” effect. Additive simply means the interaction between two chemicals equals the sum of their parts (e.g. 1+1 = 2). Synergistic means that when two chemicals interact, the effect is greater than the sum of their parts (e.g. 1+1 = 3. Sounds like “alternative math!”). Likewise, keep in mind that THC/CBD ratios and different strain profiles (with variable cannabinoid and terpene profiles) can influence effects.

Note: in some cases, cannabis may actually increase the effectiveness or potency of other drugs. But, even if the interaction is potentially beneficial, close monitoring by a medical professional, along with regular blood work, is important as a patient may need adjust their dosing accordingly.

Drugs That Affect Blood Sugar Levels

close up of hands making injection by insulin pen

Interestingly, there is evidence to suggest cannabis may decrease insulin resistance, improve the metabolic process, and improve blood sugar control. However, most evidence comes from large epidemiological studies that analyze general patterns, including the causes and effects of various health conditions within specific populations. (Several studies found that cannabis users had lower rates of obesity and diabetes when compared to non-users.) However, far fewer studies look specifically at how THC, CBD, or other cannabinoids interact with other drugs that have known effects on blood sugar (like insulin).

Although we don’t have conclusive evidence, it’s possible cannabis may work together with other drugs favorably. But, by the same token, there could be a risk that cannabis combined with other drugs could lower glucose levels too much. Clearly, patients should continually monitor the effects (under medical supervision) to mitigate potential risks and adjust medication appropriately.

Drugs That Lower Blood Pressure

Measuring blood pressure

One of the major features of THC is that it simultaneously activates the CB1 and CB2 cannabinoid receptors. Activating both receptors induces a cardiovascular stress response that can elevate cardiac oxygen consumption while reducing blood flow in coronary arteries. While reports of adverse events are relatively rare, patients who are taking blood pressure medication should be aware that cannabis may compound effects.

RELATED STORY Cannabis and Its Impact on High Blood Pressure

Drugs That Increase Risk of Bleeding


Both THC and CBD may increase the effect of drugs used for blood thinning (e.g. warfarin or heparin), or drugs known to carry their own risk of blood thinning (e.g. ibuprofen, naproxen, etc.). How? By possibly slowing down the metabolism of these drugs. To a lesser extent, THC may displace warfarin from protein binding sites.



Most studies suggest there is a bidirectional modulatory relationship between the body’s natural opioid system and the body’s natural cannabinoid system (the endocannabinoid system). However, characterizing the specific mechanisms by which they interact proves challenging. Nonetheless, the pain-relieving properties of cannabis are well-established. And, many medical professionals have come forward to suggest cannabis (as an alternative pain medication) could play a role in stemming the overuse of prescription (and illicit) opioids.

RELATED STORY How Cannabis Could Turn the Opioid Epidemic Around

There’s no question. From an abuse potential and toxicity perspective, cannabis as a substitute to narcotic pain medications would be a far better first-line drug for management of chronic pain.

However, what about as an adjunct to opioid therapy? How does cannabis measure up? Could cannabis reduce a patient’s reliance on opioids, or would combining the two elevate risk of concurrent dependency or abuse?

Examining the subjective effects of vaporized cannabis in conjunction with opioids, Dr. Donald Abrams, an oncologist from UC, San Francisco, and his team published a small study in 2011. They found no significant change in opioid blood level concentrations after exposure to cannabis. Moreover, patients reported a 27% decrease in pain following cannabis administration.

Abrams concluded that cannabis can, in fact, safely augment the pain-relieving effects of opioids. His team also found that combining opioids and cannabis may allow for treating patients with lower opioid doses while reducing risk of dependency and fewer side effects. Several other studies, which we’ll explore further in an upcoming series, support the findings from Abrams’ study.

RELATED STORY What Are the Best Cannabis Strains for Pain?



Mixing alcohol with virtually any drug is generally not a good idea. In fact, mixing it with some drugs (particularly opioids and central nervous system depressants like benzodiazepines, barbiturates, and sleep meds) can prove fatal. But, what about alcohol and cannabis? There’s no doubt: cannabis and alcohol is a popular combination. But what does the research say? Is mixing these two substances okay?

Overall, drawing a conclusion based on available research is subject to interpretation and personal biases. The same studies can be interpreted positively or negatively, depending on your perspective. On the one hand, studies have provided compelling evidence that alcohol increases blood THC levels (although no evidence suggests the converse–that THC increases blood alcohol levels). On the other hand, some research suggests people consume less alcohol when they use cannabis.

These two findings aren’t mutually exclusive. In fact, they make sense. If THC reacts to alcohol by potentiating the desired effects on mood, then one would need less alcohol.

After digging back to 1985, I did find one study published by the National Institute on Drug Abuse (NIDA), Alcohol and Marijuana: Concordance of Use by Men and Women, that examined consumption pattern differences in three different environments (only alcohol is available, only cannabis is available, both are available).

Here’s what they found:
•14 out 16 subjects drank significantly less alcohol when both alcohol and cannabis were available (compared to when only alcohol was available)

•12 of the 16 subjects consumed slightly more cannabis when both were available (compared to when only cannabis was available)

Basically, when people have access to both substances, their consumption patterns change: they smoke a little bit more, but they drink a lot less! It was a small study, so we can’t necessarily generalize the findings; however, they do seem consistent with most people’s experiences.

That being said, one still needs to be cautious. For one, alcohol and cannabis together pose even greater dangers driving than when using either one independently. Second, if someone has had too much to drink–to the point they need to vomit to expel the toxins–know that cannabis inhibits nausea and vomiting. By preventing yourself from vomiting, you’re putting yourself at greater risk of suffering from alcohol toxicity.



Many sedatives–such as alcohol, benzodiazepines (Ativan, Valium, etc.), some antidepressants, barbiturates such as phenobarbital, and narcotics such as codeine–influence GABA neurotransmitters in the central nervous system, producing a calming effect. Likewise, cannabinoids like CBD and THC as well as terpenes like myrcene and linalool, can produce sedative effects. (Although, each of these compounds produce effects differently, and sometimes paradoxically. For example, higher doses of THC can actually be stimulating and increase anxiety, while CBD can be both calming or wake-inducing.)

When combined with sedatives, cannabis produces an additive effect. Cannabis doesn’t seem to elevate blood levels or potentiate the sedative actions of other sedatives (as would be the case if it were synergistic effect). Therefore, while it’s not as risky as mixing alcohol with sedatives (which can prove deadly), the combination is still risky. Users should exercise extreme caution, or better yet, avoid the combination altogether.

CBD and Cytochrome P450

Neuron cell network

Cytochrome P450 isn’t a drug. It’s a class of essential enzymes known to play a significant role in drug interactions–not just with cannabis, but many drugs. Although evidence suggests CBD is largely safe, well-tolerated, and non-addictive (even anti-addictive), in some patients it can interact synergistically (beneficially or adversely) with other medications. How so?

Most notably, the interplay between CBD and cytochrome P450 seems be most prominent when it comes to epilepsy and anti-seizure medications. One small study published in 2015 found that CBD elevated blood concentrations of clobazam (an anticonvulsant) in children while elevating norclobazam (an active metabolite of clobazam).

The good news is the remedy seems fairly straightforward: reduce the dose of clobazam, which reduces side effects. Moreover, the study found that all but four of the subjects (out of 13) had a 50%+ reduction in seizures. The researchers concluded CBD (in combination with clobazam) is a “safe and effective treatment of refractory epilepsy.”

There are a few other potential interactions that we’ll go into more depth in an upcoming series. But in short, CBD inhibits breakdown of warfarin (a blood thinner), thereby increasing its duration of action and effect. Patients taking CBD-rich products should pay close attention to changes in blood levels and adjust dosage accordingly as instructed by their doctor. Also, patients who are undergoing chemotherapy and taking CBD should be aware that the same dose of chemotherapy may produce higher blood concentrations.

In Summary

For most patients, cannabis is relatively safe, well-tolerated, and carries fewer risks of adverse drug interactions than many other commonly prescribed drugs. Nonetheless, cannabis is not a single drug; it’s a complex plant comprised of numerous compounds from cannabinoids to terpenes. Influenced by these cannabinoid and terpene profiles, potential interactions, both good and bad, can vary from strain to strain. Drawing broad conclusions on how this “pharmacological treasure chest” interacts with other drugs is inevitably imprecise.

Nonetheless, given its therapeutic versatility, one of the most compelling arguments for cannabis is that it can actually reduce the need to combine multiple medications that have a high risk potential of producing adverse interactions. Dr. Donald Abrams, chief of hematology-oncology at San Francisco General Hospital and a professor of clinical medicine at the University of California, San Francisco, echoes this important but often overlooked point: “Why would I write six different prescriptions, all of which may interact with each other, when I could just recommend one medicine?”


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Re: How Does Cannabis Interact With Other Drugs?

Post by Fat_old_dwarf »

Interesting. It's something you don't hear much about, at least from those with figures to back up their findings. It explains why, when soapbar became ubiquitous in my neck of the woods, why I would have a morning drink with my wake and bake, because otherwise it didn't work. (And at that point I gave up cannabis for years, because I'm not much of a drinker, let alone one who drinks in the morning. I thought I'd developed permanent tolerance. Only years later did I find out what the stuff was.)

Also, it sheds some light on the eternal tobacco arguments. Nicotine has the least effect on its own of any drug I know, but it potentiates (never say that word) others. I don't like mixing cannabis with tobacco, but I often have a roll-up afterwards, and I don't think the difference it makes is all in my head. Though I agree it's minimal considering the damage tobacco does.
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Re: How Does Cannabis Interact With Other Drugs?

Post by Jesscass »


Personally I know that soapbar is still big with at least smack heads and/or homeless people(latter one especially as a 'booster' combined with alcohol and for synergy effect not only along this group of course, as popular as ridiculous classic mix of stimulants with alcohol ; of course again among other things)for some reasons also mentioned in this article.
I know I'm anal again but think it's a bit exaggerated as even the worst gear at least got me slightly high even with a high tolerance(noticeable at least)so same with shitbar or other crappy gear but I hear that a lot ; same with people funnily thinking drinking alcohol in the morning is fucked up but lighting up in the morning seems to be more okay , oh those hierarchies again :lol: (For the record: each to their own believe it or not but if one is doing any of those drugs on a regular when starting one's day this is at least equallly problematic that's my point.).
Also I know soapbar is going to prisons and sold there(like so much else of course)at horrible prices as usual there ; no one should go to prison for drugs but dealers of soapbar and border afghan should :lol: !

Nicotine: fortunately I figured out before ever trying this how pointless mostly this drug is. As far as I'm informed especially THC pontentiates Nicotine but at the same time Nicotine ambivalently surpresses THC, this is documented, too. Noticed this a lot personally when uneducated but regulary consuming people used to mixing smoke pure wiet for the first time as they think nothing happens as cannabinoids seem to need some time to enter bloodstream ; ammonia which seems to be a regular tobacco additive ensures Nicotine as THC entering the bloostream a lot faster in both cases, go figure.
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Re: How Does Cannabis Interact With Other Drugs?

Post by Fat_old_dwarf »

Jesscass wrote: Sat 25th Mar 2017 09:50 pmsame with people funnily thinking drinking alcohol in the morning is fucked up but lighting up in the morning seems to be more okay , oh those hierarchies again :lol: (For the record: each to their own believe it or not but if one is doing any of those drugs on a regular when starting one's day this is at least equallly problematic that's my point.).
You do seem to have some compelling need to fall out with everyone, don't you? It's not so much the disagreement as that 'I'm the only one who can think logically' tone.

Drugs are different. People are different. For myself -- I've done numerous day trips to Amsterdam, arriving as early as 4AM and leaving late in the evening. I couldn't imagine doing that if I were drinking -- I'd be feeling tired and slugged by 10 at the latest, not enjoying anything and struggling to stay awake. But then, there are drinkers who could manage it, and smokers who couldn't.

By your logic, I could say 'same with people funnily thinking shooting up heroin after work is fucked up but smoking a joint seems to be more okay'. If it's fine to smoke cannabis, why isn't it the same with heroin? Well, you see, they're different drugs.
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Re: How Does Cannabis Interact With Other Drugs?

Post by tot ziens »

By relatively safe you should consider Cannabis has been used medically and recreationally for 7,000 years and hasn't killed a single person. Last year 88,000 people died of alcohol poisoning in the United States alone. Cannabis is non toxic to human beings has no LD50.
As far as addiction, it's not physically addictive but it does make me grumpy and act like a dick for a week or so when I take a break from it. 👍😄
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Re: How Does Cannabis Interact With Other Drugs?

Post by Fishzhil »

No doubt, there’s a lot of buzz surrounding the potential benefits of medical marijuana. But we have a lot of research with no answer on how cannabis might interact with prescribed or over-the-counter medications a person may also be taking. Some years ago, they said that CBD might reduce the effectiveness of other medications, including antidepressants like Cymbalta or duloxetine.
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Re: How Does Cannabis Interact With Other Drugs?

Post by FawnWitmer »

It depends on what other drugs you are taking and how its use can interact with other drugs. But yes the chances of interact are very high in some cases where you are fighting against the severe diseases. That's why I prefer CBD topicals as compared to their oral use.
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