Cannabis & pharmaceutical drug interactions overview

On the ways cannabis & prescription medications can interact.

Cannabis & Pharmaceutical Drug Interactions: Potential Risks & Hazards To Be Aware Of

High There

By High There

August 27, 2021

As medical marijuana prescriptions are becoming more and more common across the United States, gaps in our knowledge about cannabis, often due to years of prohibition, begin to show themselves.

Though cannabis research is an ever-growing field, little data and information has been gathered prior to the last decade about the interaction of cannabis and other prescription medications. 

Cannabis use itself is rarely harmful and has never resulted in a proven fatality, but cannabis use in combination with other substances or medications could result in as-of-yet-unknown issues.

In today’s article we’ll be talking about cannabis & pharmaceutical drug interactions; how cannabinoids may alter the effects of other prescription medications, or be altered in turn by taking other substances alongside them, and whether or not these interactions are always a harmful thing. Let’s dive in.

White pills against a blue background
By Halacious via Unsplash

Cannabis & Other Pharmaceuticals

Cannabis use has been prevalent through-out a large swatch of human history, but recent (in the larger scale) prohibition of marijuana use has led to a lack of verified, peer-reviewed data on the topic as a whole. 

Though researchers in other countries have carried forward with attempts at understanding cannabis on a deeper, more scientific level, the United States has long flagged behind in cannabis studies. Or at least until more modern times.

As cannabis legalization has spread, both across the US and the rest of the world, the last 10 to 15 years have seen a boom of newly available research, much of it revolving around the use of cannabis as a medicinal treatment. Chronic illnesses, neurodegenerative diseases, nausea and mental health – All ailments that have shown promising results from being treated with cannabinoids.

But, for many, other forms of medications may be required to help address their specific health needs, and

drugs are somewhat scarce.

What Is A “Drug Interaction”?

When two substances that can affect the body are taken at the same time, chemical reactions between these components can change and alter the effects of each.

If you’ve ever taken a prescription medication, odds are your medicine bottle includes a small warning label on the side that lists instructions for those taking said medication, such as “do not operate heavy machinery” or “do not drink alcohol”.

Alcohol in particular is an excellent example, as drinking while taking virtually any prescription medication will have some level of effect – Either making the sensation of drunkenness more heightened, or blocking the medication from fully accessing the body’s liver/metabolic system. For some pharmaceutical drugs, alcohol abuse while medicated can lead to organ failure, brain damage, and even death.

Thankfully cannabis use is, on the whole, seen as more benign & generally safer than alcohol, and carries less risk of violent or lethal interaction with most pharmaceutical substances. However, that doesn’t mean that marijuana cannot interact with other drugs.

A hand holding pills
By Ksenia Yakovleva via Unsplash

Metabolism & Pharmacological Action

When our bodies intake substances – Food, water, chemicals, and anything in between – it is processed by some part of our metabolic system. 

In particular, many pharmaceutical drugs are processed by the same metabolic pathways inside the liver as cannabinoids, ultimately broken down by genetically-produced enzymes of the Cytochrome P450 system (or “CYPs”). Our unique genetic makeup can affect exactly what types of CYP enzymes are present in our bodies, and how effective they are, but those levels of effectiveness can also be altered.


, such as overall health & nutrition, circulation strength in the liver, age, and other biological differences, finding a change in either enzyme induction or inhibition brought about by the intake of mind & body-altering chemicals (prescription or otherwise) is also common. 

It is when the induction/inhibition of the body’s metabolic enzymes are altered by a foreign substance, then altering the effectiveness of a secondary substance, that we reach the concept of a “drug interaction”.

How do Drug Interactions Work?

There are two recognized fashions of drug interaction: “pharmacodynamic” and “pharmacokinetic”.

Pharmacodynamic interactions usually occur when an individual takes two substances designed to interact with the body in the same fashion, IE: two separate drugs each designed to affect the same, specific neurological receptors in the brain. Typically this can be avoided by knowing what you’re taking – Your medical health professional should be well aware of these interactions, and will avoid prescribing medication that can have negative combined effects.

Less predictable – and more commonly seen – are the pharmacokinetic interactions, wherein one drug alters a basic biological function of the body that a secondary drug then interacts with. Particularly for substances with more variable dosage amounts (IE: the aforementioned alcohol) these interactions can be unpredictable, as amount taken, form taken in, and individual metabolic systems can all come into play.

Do Cannabinoids Interact With Other Drugs?

Research has shown that the varying forms of cannabinoids available in marijuana – THC, CBD, and many others – can have interactions with varying pharmaceutical medicines. A

evaluated existing studies done on five prescription-strength CBD & D9 THC medications, including Sativex and Marinol.

In their research, the Penn State team looked at how each of these medications affected varying cytochrome enzymes, noting that each altered the body’s ability to metabolize specific compounds – Compounds that may then cause an increase in effects for other drugs taken that interact with these same inhibited enzymes.

Ultimately the team came up with a (non-exhaustive) list of 57 known medications that can have potentially lethal interactions with cannabinoids; commonly recognizable names include clobazam (a seizure medication), fentanyl (a synthetic opioid) and warfarin (a blood thinner). (


All of these drugs listed are known as “NTI”, or “narrow therapeutic index” medications – Defined as “drugs with small differences between therapeutic & toxic doses”, this means any interaction with other drugs can lead to disastrous consequences.

Assorted pills on a pink background
By Anna Shvets via Pexels

Are All Cannabinoid Interactions Bad?

Absolutely not. While we’ve mostly addressed the topic of cannabis interactions with other prescription medications, cannabinoids interact with a wide variety of other substances when used, many of which can help change & alter the effect.

As mentioned before, the cannabis plant is composed of a number of different chemical compounds – Most commonly we associate various cannabinoids with marijuana, but other chemicals, such as scent-and-taste-laden terpenes, also fill out the plant’s composition.

One common interaction between cannabinoids themselves is with Delta 9 tetrahydrocannabinol and cannabidiol/CBD.

showed a strong counteraction of the psychotropic effects of D9 THC from CBD – In fact CBD may be one of the few methods of calming down from an intense high that is truly effective, though dosage amounts needed may vary from individual to individual.

Likewise it is commonly believed that the terpenes themselves have a significant effect on cannabis, with varying types and ratios of terpene compounds providing more sedative, calming, or energetic properties depending on what terpenes are present and in what amounts. 


has caused some , and may come down more to the presence and ratio of varying cannabinoids instead, anecdotal evidence for some fashion of experience alteration based on the individual chemical makeups of different cannabis types has long been seen as commonly accepted knowledge, and is a common part of many modern medical marijuana treatment programs.

How Can I Avoid Bad Interactions With Medical Marijuana?

First and foremost, speak with your health care provider about your cannabis use, either recreational or medical – Particularly recreational, as your doctor will likely already be aware of your cannabis use & medication routine if you are prescribed marijuana as a medical treatment. Your doctor will know what medicines are likely to interact with cannabis, and can help make sure you steer clear of any unwanted effects.

Likewise, avoid taking unknown & prescribed medications (this is generally sound advice regardless of whether or not you use cannabis). Without knowing precisely what you’re taking (and again, as best dictated by your physician) any number of detrimental interactions could occur – Interactions that can be difficult to diagnose and treat. If you don’t know what you took, neither does your doctor.

And bear in mind that common, legal substances such as alcohol or tobacco can also interact with medications, both cannabinoids and otherwise. Both alcohol and tobacco use are notable for harsh interactions with specific NTIs and other medications, and should be avoided if directed by your healthcare specialist.

If still unsure about the safety of combining your prescription medication with cannabis use, there are several websites that may be able to help. Though no replacement for the advice of a licensed medical professional, the following websites have thorough, respected databases on drug interactions the home consumer can use to seek information on any medication they may be taking.

Wrapping Up

We hope today’s article has helped shed a little light on cannabis as a medical treatment, and maybe even quelled a few fears. 

Though cannabis use isn’t without it’s potential perils, for most individuals their consumption is likely to remain safe. So long as you are capable of being honest with your personal medical advisor about your cannabis use you should be advised by them when about to start any medication that could have negative interactions. Stay safe, and as always, happy smoking!

This article has been reviewed by

, medical advisor to the High There staff & editorial team.

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