Despite being discovered in 1942, Cannabidiol (CBD) is still relatively new to the clinical scene. Many of CBD’s features (anti-inflammatory, anxiolytic, analgesic) show great clinical promise. But scientists still aren’t fully sure how this unique compound affects us in the long run. And we here at The Greenest always use caution when it comes to incorporating CBD into your diet or lifestyle. While we’re big proponents of CBD, it’s not for everyone. Those with certain medical conditions or on certain diets should steer clear of CBD. So let’s break down when you should steer clear of using CBD. Here’s our list of when you should not mix CBD with certain medications and foods. This isn’t a completely exhaustive list. Mostly because the science and clinical research keeps evolving. But you can use this as a helpful guide to know when CBD may or may not be right for you.
One area of particular concern are potential drug interactions. CBD is metabolized by the CYP family of enzymes. These enzymes are also responsible for metabolizing many conventional drugs we consume.
Here are the most significant CBD drug and food interactions we know of today. Don’t Mix CBD with these medications and foods:
1. Cytochrome (CYP450) family of enzymes
As mentioned prior, this group of enzymes is responsible for metabolizing or breaking down a wide range of drugs that enter our system. CBD can impact the activity of CYP450 enzymes. In the short run, CBD can inhibit activity of CYP enzymes, a phenomenon which can result in increased drug serum levels, when consumed at higher doses. In the long run, CBD may induce or increase production of CYP enzymes, resulting in more rapid metabolism and degradation of several drugs.
Thus, it’s recommended that you check with a medical provider before combining CBD with drugs metabolized by CYP450. Some drugs that have CYP450 interactions include:
- “SSRIs, tricyclic antidepressants, antipsychotics, beta-blockers and opioids (including codeine and oxycodone).
- macrolides, calcium channel blockers, benzodiazepines, cyclosporine, sildenafil (and other PDE5 inhibitors),
- antihistamines, haloperidol, antiretrovirals, and some statins (atorvastatin and simvastatin, but not pravastatin or rosuvastatin).”
The opposite can also be true. Some CYP450 drugs will affect the way in which CBD is metabolized. Drugs such as ketoconazole, itraconazole, ritonavir, and clarithromycin may inhibit CBD’s breakdown in the body, leading to an excess build up of CBD. Other drugs including phenobarbital, rifampicin, carbamazepine, and phenytoin speed up CBD’s metabolism, reducing its overall bioavailability.
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2. Blood thinners
Perhaps the most serious common drug interaction with CBD occurs in patients taking Warfarin. Research uncovered at Harvard Medical School warns patients that CBD’s inhibition of CYP450 can increase levels of blood thinners such as Warfarin. Excess serum concentrations of Warfarin and other blood thinners can be dangerous. We advise patients to avoid concomitant use.
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3. Grapefruit juice
Though not a drug in and of itself, grapefruit juice is another substance you may not want to combine with CBD or most medications. Why’s that? Grapefruit juice can also act on CYP enzymes. It has also been estimated to affect the metabolism of numerous medications. The effect can also be cumulative as grapefruit juice has a duration of 24 hours in the body.
One of the first approved medical uses of CBD was for the treatment of severe epilepsy in conditions such as Dravet syndrome and Lennox-Gastaut syndrome. It might surprise some to learn, then, that CBD administration can affect anticonvulsant drugs. Taking CBD with Clobazam, a benzodiazepine used to treat seizures, resulted in increased serum levels of Clobazam thanks to CYP inhibition.
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CBD may impact other drugs used to treat epilepsy. These include:
Do not take these drugs with CBD. Co-administration with CBD has been shown to “significantly change” many of these drugs in the body. Researchers have also discovered that patients who took Valproate, an anticonvulsant, were at increased risk of having elevated liver function enzymes.
As such, extreme caution should be used when combining CBD with other epileptic or anticonvulsant drugs. In short, don’t Mix CBD with these medications.
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Ketamine is a dissociative anaesthetic. It is commonly used to sedate patients before surgery. It’s known to produce euphoria coupled with a lack of response to stimuli, known as a dissociative state. It also has analgesic (painkilling) properties, which is perhaps why it’s been in clinical use since the 1960’s.
Many people view Ketamine as a party or club drug. However ketamine can also cause cognitive distortions such as extreme agitation and confusion known as psychomimetic states. Researchers are still unsure as to how ketamine interacts with other substances, noting that, “…the safety profile of ketamine appears to be altered when used in a polydrug manner.” Whether this applied to CBD and THC or just to one compound remains to be determined.
6. Drugs that act on metabolic enzymes
Research has suggested CBD can exhibit inhibitory effects on the UGTs. These enzymes are all about metabolism. They are responsible for the elimination of potentially toxic agents such as xenobiotics and other endogenous substances. Many of the drugs that act on these UGTs are very commonplace and include acetaminophen and ibuprofen.
“Even basic, everyday over-the-counter medications are implicated. Medicines such as over-the-counter naproxen and ibuprofen, could lead to significant side effects — such as bleeding. We’ve seen this with both medical and consumer use of CBD,” researchers conclude.
CBD’s has had inhibitory effects with UGT1A9 and UGT2B7. As such researchers “recommend[s] dosing changes in the presence of CBD” for the following drugs:
- Valproic acid
Researchers advise caution when administering these with CBD:
“CBD should be used with caution in patients stabilized on or newly initiating these medications and side effects related specifically to the substrate’s toxicities should be monitored given UGT inhibition will decrease their excretion and increase bioavailability.”
Don’t freak out about combining CBD with aspirin. But we suggest exercising caution since we don’t fully understand the long term effects.
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7. Don’t Mix CBD with Medications and Foods – The Miscellaneous Category
We can’t say with confidence which drugs will definitively interact with CBD. That’s because all drugs haven’t been clinically tested. We always need more research. For the time being we can examine the Indiana University Department of Medicine’s list of pharmaceutical drugs and medications that may be contraindicated for use with CBD. A few of the drugs on that list include:
- Steroids and corticosteroids
- HMG CoA reductase inhibitors (statins)
- Calcium channel blockers
- Prokinetics (motility drugs)
- HIV antivirals
- Angiotension II Blockers
- Oral Hypoglycemic Agents
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In Conclusion – Don’t Mix CBD with These Medications and Foods
There’s a lot we don’t know about CBD. Luckily, science is doing more research all the time. Consult your doctor before starting any CBD regimen. That’s a good rule to go by if you are on many medication or not. But use this list of medications and foods that we currently know don’t mix well with CBD as a guide. If you are using any of these (or if you just can’t quit grapefruit), then reconsider CBD usage. And if you have any questions or hesitancy, ask your doctor. They will be able to give you all the help you need.
Janelle Lassalle is a writer and content creator that specializes in cannabis. She’s also an insanely passionate advocate and expert in all things CBD. You can find her work featured in a variety of publications such as Healthline, The Huffington Post, Leafly, Forbes, and High Times. Check out her portfolio, or follow her on Instagram @jenkhari.