How Does Cannabis Interact with Other Drugs?

We all know what being sick feels like. It often comes with having to take different medications, so that’s when we may ask ourselves: how does cannabis interact with other drugs?

A seemingly harmless grapefruit can cause problems with your anti-anxiety medication, for example, so you can imagine what happens when more complex compounds interact.

So, before you start taking any drugs and smoking a bunch of pot, you should first do your homework and double-check the indications for what you’re planning to take.

Let’s say you have a condition that you’re already treating with medical cannabis, but now you have to take another drug for a completely different condition.

The experiences of numerous patients tell us that the majority of interactions between cannabis and other medications are relatively mild.

Some people even suggest that their medication works better with cannabis, but we’ll get to that later on.

Unfortunately, because of the restrictive laws and general lack of research on the subject, we really don’t know a lot when it comes to cannabis’ interactions with other drugs. Hopefully, this will change in the years to come.

Until then, we have to rely on sporadic studies and personal accounts of individuals willing to share their experiences.

Freebie: Download a free dosage guide that will show you the exact step-by-step process Dr. Dustin Sulak used to successfully treat more than 18,000 patients with cannabis.

Types of substance interactions

Before we get to the specifics, we should give you an overview of the main types of chemical reactions between two medications or substances.

The additive effect is the sum of effects of all substances involved in a reaction, no larger than if the substances were used separately. This type of interaction usually occurs between medications that are very similar in structure.

On the other side of the coin, a synergistic effect can put you in a dangerous situation. This effect happens when “the sum of the effects is more than each chemical individually”.

For example, mixing alcohol with sedatives can increase the tranquilizing effects of both substances, which would not happen if they were used separately. This can lead to respiratory depression, resulting in death.

The antagonistic effect occurs when the substances involved in the interaction produce no effects or decrease the desired effects of one or all substances that were involved in that interaction.

Cannabis and medications

As previously mentioned, there’s basically no research on the interactions of drugs with cannabis, but the anecdotal evidence and patients’ testimonies tell us that mixing weed with medications usually doesn’t have any negative impact, or that it causes a mild interaction.

For example, a few years ago I had a wisdom tooth infection and because of that, I had to take some antibiotics.

My dentist told me not to drink any alcohol while I was taking them but added that I was free to smoke weed as much as I want since cannabis has no interactions with this type of medication.

Marijuana and sedatives interaction

Sedatives or tranquilizers are a class of medications that induce sedation by reducing excitement and irritability. But sedation is a pretty broad term, and therefore cannabis can interact in different ways with different sedatives.

In general, it seems that combining cannabis and sedatives results in an additive effect.

That basically means that there shouldn’t be any side effects when consuming these substances together. The effects of cannabis and sedatives will just add up, as the sedatives, the cannabinoid THC and some terpenes all have potent sedative properties.

Though this combination is not dangerous, as is mixing alcohol with sedatives, you can expect additional drowsiness and sedation from mixing these two. We definitely don’t recommend it.

Marijuana and antidepressants interaction

Newer versions of antidepressant drugs have been improved not to carry such high risks of contraindications and interactions with other medications and substances.

Unfortunately, the research for this correlation is also very scarce. There are only a few reported cases of adverse effects caused by mixing cannabis and antidepressant drugs. (1)

However, until we know more about this type of interaction, you should probably steer clear of weed during your antidepressant therapy, just to be safe.

You can read more about cannabis and antidepressant medications in our in-depth article below.

Marijuana and antipsychotics interaction

The relationship between psychotic disorders and cannabis is very complex. The fierce debate whether cannabis triggers mental disorders such as schizophrenia has been raging for decades.

Although marijuana definitely helps with conditions such as PTSD, anxiety and depression, patients with psychotic disorders are recommended to stay away from this plant.

But what about antipsychotic medications and weed? As it turns out, cannabis interacts with all substances that get broken down by P450 enzymes in the liver, and those enzymes are also found in some antipsychotic medications.

Since cannabis (more precisely CBD) interacts with those enzymes, when it gets into the system it prevents the antipsychotic drugs from being broken down.

In that case, antipsychotic medications are being prevented from working, which is definitely a bad thing. Mixing cannabis with these types of drugs can also result in severe sedation, diminished motor skills, impaired driving skills, and confusion.

Drugs for lowering blood pressure and cannabis

The most abundant cannabinoid THC binds to both CB1 and CB2 receptors. Activating these receptors sometimes triggers a stress response which makes us use more oxygen in our cardiovascular system while reducing blood flow in coronary arteries.

Although high THC strains elevate blood pressure and can even induce heart palpitations (irregular heartbeats) in novice users, after a brief initial period, blood pressure will definitely start dropping.

When it comes to the interaction of cannabis and blood pressure medications, once again there’s no scientific evidence of any adverse effects.

However, we strongly advise you to use those two in combination with caution, precisely because of the lack of research, and because using blood pressure medications alone carry certain risks.

Drugs regulating the levels of sugar in the blood and cannabis

The research on cannabis and diabetes is suggesting that cannabis decreases insulin resistance, improves metabolic processes, and also improves blood sugar control. You can read more about it in our article below.

Official research dealing with combining drugs that regulate blood sugar levels (like insulin) and cannabis sadly doesn’t exist yet, but many diabetes patients are using cannabis alongside sugar-regulating medications without any harmful effects.

CBD interactions with other drugs

CBD is a non-intoxicating cannabis compound with fewer side effects than its psychoactive chemical relative THC. Medicating with high CBD strains or CBD oil doesn’t induce that “high effect”, which is why numerous medical users decide to go with this cannabinoid.

However, CBD should be avoided if you are taking drugs that are broken down by the cytochrome P450 enzyme system.

CBD Oil Review indicates which medications should be avoided, so check with your doctor first before taking them with CBD.

To conclude…

Even though there’s no scientific consensus, it seems that cannabis functions well with some medications, while interfering with the functioning of other drugs.

Until science picks up the pace, we all need to take responsibility into our own hands, and closely monitor the effects of these substances combined.


  1. Kaminer Y, Goldberg P, Connor DF; Psychotropic Medications and Substances of Abuse Interactions in Youth; Substance Abuse; July 2011; 31(1):53-57
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Experienced journalist with a decade-long experience of researching cannabis. She has been featured in many prominent outlets, such as The Growth Op, National Post and The Province.

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