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Drugs That Don’t Mix with Cannabis, Part II: Prescription Drugs

In part one of this article, I covered the interactions that cannabis can have with other recreational drugs. These interactions range from mild and fairly benign to potentially life-threatening. Of course, that’s partially a result of the high level of risk that is inherent in using many of the harder drugs. 

Cannabis can also interact with prescription pharmaceutical drugs, whether those drugs are taken recreationally or taken as intended to treat a mental or physical illness. For this reason, it’s always a good idea to tell your doctor about your cannabis use. In the past, this information was protected by doctor-patient confidentiality, so it was safe to admit to it. Now that cannabis is legal, there’s no reason not to disclose cannabis use. If you are taking any prescription drugs, your doctor should be able to tell you how cannabis might interact with them. In the meantime, though, here’s what you should know:

Sedatives And Benzodiazepines 

Benzodiazepines are a class of drug that includes Valium, Ativan, Xanax, Klonopin, and more. These drugs are powerful sedatives that are often used to treat anxiety. They are sometimes used recreationally, but mixing them with cannabis might not be a great idea. This is because CBD is known to inhibit the liver’s cytochrome P450 enzymes, which help break down and metabolize these drugs. When they are inhibited, the level of the non-cannabis drug in the blood may increase, leading to an unwanted increase in the drug’s effects.

Users of LSD, other psychedelics, or even cannabis sometimes keep a few doses of a benzodiazepine on hand for when they trip. This is because the benzodiazepines reduce the hallucinogenic aspects of these trips and highs, and can be used to bring the user out of a bad trip if needed. However, this doesn’t work for everyone, and is dangerous if the user takes too much. 


In the US states that have legalized cannabis, the argument that cannabis could be used to treat pain in conjunction with opioids, allowing medical patients to reduce their doses of opioid treatments (or get off of them entirely) was an important point in the debate. Obviously, since doctors will sometimes prescribe cannabis and opioid medications simultaneously for pain, it isn’t the most dangerous mix – however, cannabis isn’t completely without risk, and opioids are obviously very dangerous. 

You should not, under any circumstances, be taking prescription opioids recreationally. However, if you have been prescribed opioids, talk to your doctor about continuing cannabis use (or beginning it). The goal should be to use both cannabis and your opioid medication concurrently to treat pain, so that you can use less opioids and less cannabis, gaining the pain-relief benefits you need while avoiding some of the more significant side effects. Do not exceed your dose, as an opioid overdose can be fatal. 


Most people know that it’s a bad idea to mix uppers and downers. The idea that they’ll “cancel each other out” isn’t a complete myth, but it’s close. Rather than actually cancelling the side effects, the combination is more likely to simply mask the effects of one drug or the other, causing the user to underestimate the amount of drugs they’ve taken and overshoot, possibly overdosing. And, even if that doesn’t happen, the combination puts a lot of strain on the heart, and can lead to heart failure. 

Of course, mixing cannabis and Adderall is on a whole different order of magnitude than doing a speedball (heroin + cocaine). Users who try this combo do it in hopes that one drug will counter the less pleasant side effects of the other, so that they can stay alert and focused while still enjoying the cannabis high. For some, cannabis also helps mute the anxiety that sometimes accompanies Adderall use. However, both drugs increase the user’s heart rate, which could add up to a racing, uncomfortably fast heartbeat. And since cannabis, like Adderall, sometimes causes anxiety, combining the two could make that side effect worse instead of better. It’s probably best avoided.

Antidepressants (SSRIs and SSNRIs)

Mixing cannabis with antidepressants won’t necessarily harm you, but cannabis may decrease the effectiveness of the antidepressant. Unfortunately, this theory has yet to be proven, but doctors have noticed that cannabis users often require larger doses of antidepressants in order to get the desired effects. This is likely because cannabis speeds up the body’s process of metabolizing the SSRIs, which means that they are removed from the body more quickly. So, it may be best to avoid cannabis if you are taking antidepressants, or at least talk to your doctor about it so that that you can adjust your dosage accordingly. On top of that, some users find that cannabis use worsens their depression or anxiety. If that’s you, you should avoid cannabis altogether.

Drugs That Lower Blood Pressure

THC activates both CB1 and CB2 receptors, which creates a cardiovascular stress response that reduces blood flow in the coronary arteries and increases the amount of oxygen that the heart consumes. This rarely causes significant problems, but it means that cannabis can sometimes confound the effects of blood pressure medication. 

Additive Effects

In many cases, cannabis doesn’t interact with other drugs in the sense that it modifies the other drug’s effects. Instead, the effects and side effects of cannabis simply “stack” on top of the effects of the other drug. For example, cannabis (especially indica-heavy strains) can cause significant drowsiness. If cannabis is combined with something else that causes drowsiness, like diphenhydramine (Benadryl), the effect is compounded. If you mix cannabis with any drugs that carry the same side effects as cannabis, you’ll likely see those side effects increase. 

In this article, I covered some of the main classes of pharmaceutical drugs. However, it is by no means a complete list. If you are currently taking any medications, make sure your doctor is aware of your cannabis use so that he or she can advise you more accurately.

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