What Drugs Should Not be Taken with CBD?

This article has been reviewed and approved for accuracy by Dr. Craig Brandman, a cardiologist with more than 20 years of experience and a passion for helping consumers make informed health decisions.

What medications are you taking? We’ve all been asked this by a doctor at some point, but have you ever wondered why? Well, when you’re prescribed new medication, your doctor should make sure it won’t interact with anything else you’re taking. Drug interactions are a simple way to describe the complex effects and side effects of taking two or more medications simultaneously. 

Drug-to-drug and drug-to-supplement interactions may not be news. However, given that CBD oil is still relatively new to the market, there isn’t widespread information available on its interactions with prescription medications. If you’re one of the 131 million Americans using prescription drugs, you’re right to be curious — and even concerned — about the potential adverse side effects of trying it with your meds. 

Let’s look at some common medications and how CBD might impact them. We also recommend that you get expert advice from your physician if you are concerned about any potential drug interactions.

Cannabinoids and the Cytochrome P450 system

When it comes to CBD interactions, there’s one little-known system at the center of it all. Enter the Cytochrome system and specifically the CYP450 enzymes — a family of proteins that help your body metabolize cannabinoids such as CBD. One enzyme in particular, CYP3A4, is responsible for breaking down CBD.  

But that’s not the only function of these incredibly active enzymes. CYP enzymes are thought to be responsible for the biotransformation of 70-80% of all clinical drugs. CBD drug interactions can occur when enzymes are prevented from adequately metabolizing prescription drugs by introducing other substances that interfere with CYP3A4. 

It’s less of a concern, but this goes both ways. Taking prescription drugs and CBD simultaneously can also reduce the effects of CBD.

CBD and the grapefruit warning

You’ve probably come across it before — a sticker warning against eating grapefruit while using prescription drugs. If this is the first you’ve heard about it, it may sound a little strange, but grapefruit can block the action of the enzyme CYP3A4, causing more of the drug to enter your blood instead of being fully metabolized. While that’s not exactly what CBD does, it’s not a far stretch. 

So, if you’re not supposed to eat grapefruits with your medication, is it wise to be cautious about mixing them with CBD? The short answer is: It’s always good to get a professional opinion before taking any products that could react with your existing medication. It’s wise to consult with your doctor before you start taking medications and CBD together.

CBD interactions with medications

What medications does CBD oil interact with? While it’s true that CBD interacts with most prescription drugs, don’t let the fear of uncertainty rule out CBD altogether. Since the degree of potential CBD hemp oil drug interactions can vary, it’s always a good idea to get professional medical advice. Let’s take a look at how CBD interacts with common prescription drugs.

CBD and Adderall interactions

You’ve no doubt heard about Adderall, whether through your own use or via the media. Adderall is a stimulant prescribed to treat symptoms of ADHD and it can produce side effects when combined with CBD. This is because Adderall is metabolized by an enzyme called CYP2D6, which CBD has been proven to inhibit. As we touched on earlier, when prescription drugs aren’t properly metabolized, more medicine will enter the bloodstream. Given that Adderall already has a bioavailability of around 75%, taking it with CBD could increase its side effects or reduce efficacy. 

CBD and metformin interactions 

Metformin is a prescription drug commonly used by people with Type 2 diabetes to help control blood sugar levels. While the liver does not metabolize metformin, CBD and metformin are both inhibitors of the liver enzyme CYP3A4, which may affect how both metabolize. If you’re planning on using both CBD and metformin at the same time, you should seek the guidance of a medical professional.

CBD and antidepressant interactions

Between 2015 and 2018, 13.2% of Americans over 18 reported taking antidepressants. Given the prevalence of this drug, it’s essential to understand any CBD interactions. Much like Adderall, many antidepressants are metabolized by the enzyme CYP2D6, of which CBD is a potent inhibitor. The risks come in the form of exacerbated side effects of both antidepressants and CBD, particularly drowsiness and nausea. 

CBD oil and blood pressure medication interactions

There’s a whole world of pharmaceuticals for lowering blood pressure — each with different metabolic pathways. It’s difficult to speak in broad terms, but if you’re taking valsartan or other beta-blockers, it’s worth considering how CBD can interact. 

Some blood pressure medications rely on the cytochrome P450 enzyme system to metabolize, for which CBD is a known inhibitor. This means that the pathway can potentially be “slowed down” by CBD, causing the drug to remain in your system for more extended periods, and increasing the likelihood of adverse side effects such as insomnia or sleep disturbance

CBD oil and alcohol interactions 

CBD in cocktails and CBD in beer are the latest craze, but is mixing CBD and alcohol actually a good idea? Well, the verdict’s still out. One study found that CBD lowered blood alcohol levels in participants when compared with just drinking alcohol alone. Others have suggested that CBD and alcohol intensify the effects of each, in particular drowsiness. There’s still much research to be conducted here, so use your best judgment when combining the two.

Other CBD oil drug interactions

The good folks over at Penn State College of Medicine researched CBD drug interactions by studying how four prescription CBD and THC medications (dronabinol, nabilone, CBD, and nabiximols) impacted Narrow Therapeutic Index (NTI) drugs. In Layman’s terms, they looked at CBD interactions with drugs that have only slight differences between therapeutic and toxic doses. They discovered 139 medications that could be affected by CBD and 57 NTI medications to be closely monitored when taken with CBD, whether medicinal or recreational. They are:

  • acenocoumarol (VKA)
  • everolimus
  • alfentanil
  • fentanyl
  • aminophylline
  • fluindione (VKA)
  • amiodarone
  • fosphenytoin
  • amitriptyline
  • imipramine
  • amphotericin
  • levothyroxine
  • argatroban
  • lofepramine
  • busulfan
  • melitracen
  • carbamazepine
  • meperidine
  • clindamycin
  • mephenytoin
  • clomipramine
  • mycophenolic acid
  • clonidine
  • nortriptyline
  • clorindione (VKA)
  • paclitaxel
  • cyclobenzaprine
  • phenobarbital
  • cyclosporine
  • phenprocoumon
  • dabigatran etexilate
  • phenytoin
  • desipramine
  • pimozide
  • dicoumarol (VKA)
  • propofol
  • digitoxin
  • quinidine
  • dihydroergotamine
  • sirolimus
  • diphenadione (VKA)
  • tacrolimus
  • dofetilide
  • temsirolimus
  • dosulepin
  • theophylline
  • doxepin
  • thiopental
  • ergotamine
  • tianeptine
  • esketamine
  • trimipramine
  • ethinyl estradiol (oral contraceptives)
  • valproic acid
  • ethosuximide
  • warfarin
  • ethyl biscoumacetate (VKA)

Does it matter how you take CBD?

The method, quantity, and even the time of day you take CBD can dramatically affect its interactions with medications. CBD oils and tinctures absorb much faster, with a higher concentration peak than topical CBD products. For example, our Full Spectrum Hemp Elixir CBD oil has increased bioavailability that helps you feel the effects in less than 30 seconds. This product could cause more significant drug interactions than our Full Spectrum Sports Gel. In some cases, simply spacing out medication and CBD ingestion will minimize interaction, but in others, the build-up of CBD in your system over time could have adverse effects.

Are CBD effects altered by prescription drugs?

Does CBD interact with medications? Yes. Do medications interact with CBD? Also, yes. In most cases where a medication’s efficacy is compromised, CBD’s effectiveness is also adjusted. That’s because when two compounds are “competing” to be metabolized, enzymes are essentially overworked. So, if you’re noticing a reduction in the effects of your CBD drops, your other medications could be the cause.

Consult with your doctor

This has been CBD drug interactions 101, and while we know our CBD, we aren’t a peer-reviewed medical journal. Even when looking at these studies, the challenge is they are designed in vivo, without the modulatory, omnidirectional nature of CBD to account for. CBD has been shown to interact with enzymes in the endocannabinoid system with the overall homeostasis of an individual’s body in mind. While we wait for more studies into the modulatory nature of the endocannabinoid system, it’s best to err on the side of caution. 

The drugs we’ve mentioned are only a selection of medications available on the market, and not all of the ones listed will result in negative or serious CBD interactions, so it’s always best to consult your doctor before taking CBD. In some cases, your doctor may ask to monitor the therapeutic effects and adverse reactions of mixing medications and supplements to determine if and how you can safely combine them.

The next step in your CBD oil journey

Caution is natural with unfamiliar territory, especially if you’re already regularly taking a NTI drug. Once you’ve spoken with a doctor and got the all-clear, you should be able to start (or continue) taking CBD oil responsibly. Our Full Spectrum Hemp Elixir is 100% organic and made without synthetically modified compounds. Our patented water-soluble technology makes our product one of the most bioavailable and quickly absorbed CBD oils on the market, meaning you’ll get to feel the full effects sooner. Check out our full range of CBD products today.