CBD and Drug Interactions



By now you've probably heard about all of the benefits of adding CBD to your supplement regimen.

But did you know that CBD can interact with other drugs you are taking? 

CBD can have both a positive and a negative interaction with other drugs.

It’s very important that you understand the effects CBD has on other medications so that you can decrease the chance of experiencing any problems.

If you want the “cliffsnotes” version of CBD drug interactions, go here: CBD Drug Interactions: Easy Guide

If you want a more in depth look, keep reading. We suggest you check out both.

Drugs and Your Liver

Illustration Of Drugs And Human Liver

Have you ever noticed that it can take up to an hour to feel the effect of a medication you took?

This is because the drug needs to be processed by your liver.

Our liver has special enzymes called the cytochrome P450, which have the function of breaking drugs down into smaller bits called metabolites. 

In this smaller form, our cells can then absorb them better or eliminate them properly.

According to the American Academy of Family Physicians, these liver enzymes are responsible for breaking down about 90% of the drugs we’re taking.

Some of these drugs[ii] include NSAIDs, beta blockers, angiotensin II blockers, antiarrhythmics, calcium channel blockers, anti-cholesterol drugs, proton pump inhibitors, antibiotics, HIV antivirals, anti-epileptics, anti-diabetics, antipsychotics, antidepressants, anti-anxiety medications, antihistamines, and anesthetics.

That's a lot of commonly used drugs.

So if you’re taking CBD or planning to include CBD in your medication regimen, there's a high chance that CBD is going to affect other drugs you’re currently taking. 

This is why we advise you to always speak with your doctor before taking CBD.

CBD and the Cytochrome P450 Enzymes

Just like many other drugs, CBD is broken down by the cytochrome P450 enzymes.

CBD also has a special effect on the P450 enzymes: when CBD attaches to the enzymes, it inhibits them and prevents them from breaking down other drugs.

This effect can be both advantageous and problematic for the CBD user.

The Disadvantages of Using CBD with Other Drugs

CBD's action on the P450 enzymes causes other medications you may be taking to stay in your blood for longer than normal.

Here's how it works

CBD inhibits the P450 enzymes and stops them from doing their normal job of breaking down your other medications. 

Since these medications are not getting broken down, they stick around and hang out in your system. 

Basically, CBD can make other drugs overstay their welcome in your body.

This can be problematic for the CBD user. Take for example an anticoagulant drug called warfarin. 

This drug makes the blood thinner so blood clots won’t form, block the blood vessels, and cause a stroke or heart attack.

We researched a study where a patient was hospitalized and diagnosed with gastrointestinal bleeding. 

After about a week in the hospital, he was sent home only to return a couple of weeks later for persistent bleeding of the nose and easy bruising. 

Of course his doctors had to investigate if the patient was doing anything to contribute to these problems. 

They discovered that the patient had been smoking cannabis. 

Man Lights A Joint

So what does this show?

While we don't know the exact cannabinoid profile of the cannabis the patient was using, the cannabis may have increased the anticoagulant effect of warfarin in thinning his blood, which thus led to his bleeding problems!

Consider another example: a group of children who were taking antiepileptic drugs like clobazam and norclobazam were also given CBD. 

While CBD significantly helped reduce the number of seizures they were having, blood tests also revealed a higher concentration of the antiepileptic drugs in the children’s blood!

But why is this a negative effect if the seizures were reduced?

Because the more the antiepileptic drugs stay in the system, the more side effects they will produce like restless sleep, lethargy, tremors, appetite loss, urinary problems, loss of motor control, and irritability.

Long-term users of antiepileptic drugs are at a higher risk for developing liver disease, and if their levels always stay up, then it could lead to irreversible liver damage!

The same goes for strong painkillers like codeine and oxycodone. 

While CBD helps them stay longer in the system and prolong their pain-killing effects, it also increases the risk of developing adverse side effects from these drugs like constipation, drowsiness, vomiting, nausea, and even liver disease.

CBD can increase the efficacy of many commonly used medications. 

While this can obviously be a good thing, it can also be a problem because it leads to a higher concentration of the medication in the blood. 

A higher concentration of the medication will increase the chances of adverse side effects from a drug as well as potentially be harmful to your liver.

But not all interactions between CBD and other drugs are bad. CBD can beneficially interact with other drug as well.

The Advantages of Using CBD with Other Drugs

CBD And Other Drugs

CBD can enhance another drug’s effects so well that the user can decrease the dosage of the other drug.

One example of this is with epilepsy medication. 

For some people, combining CBD with their daily epilepsy medication allows them to decrease the dose of their epilepsy medication. 

This is a big deal. By taking a smaller dose of the epilepsy meds, the patient is liberated from the adverse side effects they were experiencing from the higher dose they were using before they added in the CBD.

Go here to read Alex's story about how he uses CBD to decrease his epilepsy medication dose

Under the supervision of a doctor, adding CBD to your daily regimen has the potential of being an excellent add-on therapy for many medical conditions. 

Notice how in Alex's story he got his doctor's approval before adding CBD to his daily medication regimen.

CBD-rich products could potentially be considered as an add-on therapy for patients going through chemotherapy. 

CBD and THC (especially when used together) are both very good at relieving nausea, vomiting, and the loss of appetite experienced from chemotherapy. 

CBD has anticancer effects of its own and enhances the effects of chemotherapy drugs since it also prompts cancer cell death.

Like chemotherapy, CBD has demonstrated the ability to kill different types of cancer cells including breast, colon, leukemia, lung, prostate, and brain cancer cells. 

But unlike chemotherapy, CBD doesn’t harm healthy cells (chemo can harm good and bad cells at the same time). 

Instead, CBD, as a potent antioxidant, protects non-cancerous, healthy cells while killing off cancerous cells.

Using CBD with Other Medications

CBD Oil And Different Medications

In numerous studies, CBD has been demonstrated to be a safe and effective drug.

It has the potential to improve numerous medical conditions from acne to epilepsy and chronic pain, with very few side effects, if any at all.

While side effects are not common, they can happen. 

Some side effects you may experience with CBD are lightheadedness, dry mouth, upset stomach, diarrhea, and sedation.

If you do get some mild but unpleasant side effects with CBD, try decreasing the dose. 

Oftentimes, negative side effects from CBD are from taking too high of a dose. 

Start with a low CBD dosage first, assess its effects, and either increase or decrease the dose until you find a dose that can effectively control your symptoms.

If you're just starting out and you don't know how much CBD to take, a typical start off point is 5 – 10 mg, one or two times per day.

But before you add CBD to your treatment regimen, consult with your doctor first. 

He’s familiar with your medical condition and the medications you’re taking. 

He can order blood tests to monitor the levels of your medications in your blood and adjust their dosages to avoid complications.

Do the “grapefruit test” with your doctor. 

Thanks to Martin Lee of Project CBD for inspiring the creation of the “grapefruit test”. The “grapefruit test” is when you ask your doctor if any of the medications you are taking are affected by eating grapefruits. 

The way our body metabolizes grapefruits can affect many commonly used drugs. CBD acts in the same way as a grapefruit, only even stronger.

If your doctor says yes to the grapefruit test, you know you need to discuss your CBD usage with him as well. 

If your doctor knows nothing about CBD, educate him about it. Show him our site.

While the interaction of CBD with other drugs is a real concern, we haven't come across many cases of serious complications experienced by people using CBD. Still, we want you to be cautious.

Work with your doctor or a pharmacist you trust. 

Be compliant with their recommendations, especially when it comes to regular laboratory checkups, and report any side effects you may develop.

Your doctor may decide to monitor your blood work more closely if you tell him you want to take CBD. 

Alternatively, he may just recommend you don't take your CBD too closely to the time of day you take your other medication.

When used safely, CBD may help you reduce your prescription medication dosages and ultimately their side effects as well.

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  • George says:

    According to the MicroMedex Drug App, which I had on my phone when working as an EMT, CBD oil and Sildenafil (generic for viagra) may cause a myocardial infarction. See

  • Thank you for sharing this, George. It’s important to always be cautious, especially for the elderly.

  • Arellia says:

    How does CBD affect the system like grapefruit and still be acceptable for chemo patients? My daughter is in chemo, and we were told to avoid grapefruit (not a problem for a 5yo?). But, I see CBD mentioned as a compliment to chemo mentioned all over the internet. Can you explain?

  • Hey Arellia. Thanks for your great question. I will do my best to help. The point you bring up is important — CBD can have an interaction with certain drugs in much the same way as grapefruit. This is why it’s necessary to check with a physician before using CBD. A physician or pharmacist will be able to tell you if CBD should be avoided completely or taken at a different time than other drugs. Many people use CBD and cannabis products as a complimentary therapy to their already existing medication. This can work well but to ensure safety, it’s important to check with a doctor or medical professional first. I hope this answers your question 🙂

  • Lori says:

    Are we talking CBD from Marijuna or Hemp. It would make a difference with amount of THC.

  • Hey Lori. Thanks for your inquiry. The information is regarding CBD in general, whether as isolate, derived from hemp, or derived from marijuana.

  • Melinda says:

    Love the information on this site. I have done a ton of research on CBD oil – my husband just started using it for insomnia and it has been a life changer for him. for myself though – I really want to use CBD oil for my MS (which would be amazing). my concern is that I take Rebif (interferon 1a) by injection 3x/wk. Since rebif is metabolized by the liver (my liver enzymes went way up for about 1/2 year)…how will the CBD oil effect it – make it stay in the system longer???? I don’t take any other meds and I know the CBD oil would help with my symptoms so much…..just weighing out the options. thanks.

  • Hello Melinda. Thanks for your kind feedback and question. I am happy to hear about your husband’s success. Please check with a doctor as CBD can interfere with the metabolism of other drugs. Thank you.

  • T. Hall says:

    my husband takes the following medications:amlodipine, atorvastatin, donepezil, memantine, tamsulosin, glipizide, benazepril, myrbetriq, aspirin 81 mg, and vitamin.
    Do you see any medication that may have an adverse affect?
    I bought some CBD soft gel 15mg capsules, but have been afraid to start them for fear of an adverse interaction with his other medicines. He has alzeheimers (3years) and is a type 2 diabetic with 46 units of insulin each night. His doctor is never in encouraging about any supplements. Please give me your opinion.

  • Hello thank you for your question. I cannot provide an opinion because I am not a doctor. Please seek out a different doctor who will be able to provide you the advice you need. Thanks.

  • Linda says:

    I take Some for muscle spasms. When I took CBD oil, I went into withdrawals. I waited it out for a few hours, took more oil and withdrawals worsened. Why is this happening? I want OFF prescriptions and use CBD oil only.

  • Hi Linda. We don’t have the medical background required to answer your question. Please speak to a doctor about this.

  • Deanna Doss says:

    Can you take cbd oil along with an antibiotic or blood pressure pill,I also takeheart burn pills and inhalers for copd

  • Hey Deanna. Thanks for your question. I’m not able to answer that as I don’t know exactly what you’re taking and I’m not a doctor. The person to speak with is your doctor or pharmacist. Please consult with them before taking CBD.

  • Frank says:

    Nowhere in the article does it mention this. Just FYI

  • Thanks Frank. What were you referring to exactly in the article? We love hearing feedback from our site visitors and users 🙂

  • Peter Brodie says:

    Interesting – but of no interest to me personally. I don’t take prescription drugs; not even warfarin, of which I was advised, “Everyone over fifty should be on it.”

    As it turned out, a carotid artery ultrasound scan showed that I had no plaque deposition at all. Hmmm….. Something to do with my dietary choices maybe? Possibly my refusal to believe what the food and pharmaceutical industries misled the medical practitioners with? Maybe something to do with abstaining from dairy produce? Or avoiding heating polyunsaturated fats, such as rape seed oil and sunflower seed oil? Or avoiding buying foods with damaged fats?

    There’s so much hype out there which comes not from people who actually understand food metabolism in humans, but from those who have financial interest in others getting ill, and those who swallow their misinformation whole and then pass it on barely digested.

  • Peter Brodie says:

    72 and not a drug in sight. Eating grapefruit, broccoli and kale – you know, healthy foods. Clear arteries, short and long sight both great without vision assistance, hearing excellent without hearing aids. Refused long-term warfarin, refused flu jabs – but benefitting from CBD and THC … Shortly to benefit from THCA when my own plants mature.?☺

  • Leticia says:

    Hello I’m taking CABOMETYX for kidney cancer. My question is Can I take CBD while I’m taking CBOMETYX

  • Interesting indeed! Thanks for sharing your thoughts with us, Peter 🙂

  • Wow! Very nice. Good, clean living goes a long way. Thanks for sharing this and enjoy those beautiful cannabis plants. Make sure to come back with photos for us all when they’re ready! 🙂

  • Hello Leticia. Thanks for your question. This is something we cannot advise you on. Please do check with your doctor, the prescribing physician of the medicine you are taking, and anyone else involved in your care. It’s important to know that taking the CBD will not make anything worse or have a negative contribution. Let us know if you have more questions and we will do our best to help.

  • Anoop R says:

    Hi, kindly advise if sodium valporate drug reacts with CBD oil. If yes is it advisable to continue CBD. What time duration should be maintained between cbd and sodium valporate

  • Hello Anoop. Thanks for your question! Since we cannot answer medical question of this nature, please ask your doctor this question. Thanks!


    Any comments or reports on interference with blood thinners? I have an artificial heart valve and take a blood thinner daily for life. Thanks

  • Hi Janice. Thanks for your question. Please speak with your doctor about this. Blood thinners are indeed something you need to be especially careful about when it comes to a drug interaction. Please also speak with your pharmacist.

    For an additional resource, Project CBD has recently released a comprehensive report entirely on CBD and drug interactions. You can find that on Project CBD’s website and download the report for free. It’s a good resource.

  • Elias says:

    Can i take cbd and temaflu?

  • Hi Elias. Thanks for your question. We do not have the medical background to answer that question. Please speak to your doctor and pharmacist about this. Thanks for understanding.

  • Caroline says:

    Hi, I have been taking CBD capsules for several weeks and they have really helped with the pain from a frozen shoulder. I’m now considering stopping to see if the pain will come back. Can I just stop ‘cold turkey’ or will it cause withdrawal symptoms? Should I stop gradually?

  • Hi Caroline. Thanks for your great question. We are happy to hear you found relief from your shoulder pain with using CBD. We have never heard of anyone having any withdrawal issues with CBD. As far as we know, there is no issues with stopping abruptly. Please keep in mind we are not doctors or medical researchers.

  • susan pritchard says:

    I am taking heart meds- my cardiologist said he had no issue with me taking CBD for my fibromyalgia. But he knows nothing about CBD, nor does my go. If I leave 4 hours between each dose of CBD and my other meds, is this ok?
    THEY include aspirin, beta blockers, blood thinner and anti cholesterol

  • Hi Susan. Thanks for your question. We cannot advise because we do not have the medical background to know the answer to your question. We cannot provide any medical advice. CBD has been known to interact with blood thinners. Please be careful and seek out the help of a medical professional who can help you answer this question and possibly monitor you (and your blood levels of medications) while you use CBD along with the other medications.

  • Cy says:

    I am taking Cialis 5MG daily for my Enlarged Prostrate and the side benefit of taking it daily it helps with ED. I also take Melatonin 15Mg (I have read that to achieve results with Melatonin I may have to go over 20Mg of Melatonin) and Sumatriptan for Cluster Headaches.

    I have been told that taking CBD will help with my Cluster Headaches. I have read that it goes well with Melatonin and helps there and is OK with Sumatriptan (Imitrex) for my Cluster Headache.

    I also read that CBD may increase levels of Cialis (tadalafil). But I can not find exactly what that means. It seems that it can be of value for the cluster headaches but may be detrimental for my enlarged prostrate.

    I am 73 and I know that age plays a role. I am very active, I workout 3 – 5 days a week at the gym for up to 3 hours each session. Usually 45 minutes of Cardio with usually 1.5 hours of weight training. I have been doing this for over 2 years. I have also gone vegan and have lost over 50 pounds during this period.

    My question is: How save is taking CBD oil and in what doses? and Secondly,
    What is meant by: CBD may increase levels of Cialis (tadalafil).?

    Thank you

  • Hi Cy. Thanks for your question. Please speak with your doctor or medical care provider about this. Thank you for understanding.

  • Alexander C. Bierfeldt Jr says:

    My daughter is taking CBD/THC oil. She has a brain tumor. We are currently taking an anti nausea medication. ( phenergan) can she take this Med with CBD oil?

  • Hi Alexander. We are very sorry to hear about your daughter’s condition. We cannot answer this question as we have no medical background. Please discuss this with a medical professional. It would be best to speak to a medical professional with experience with cannabis and CBD products. Thank you for understanding. We wish you all the best.

  • Kay Fisher says:

    Great information I’ve been reading about colloidal silver, do you need to use it with feminized hemp seeds at any stage? And, can you buy cannabis seeds in any state, like hemp seeds?

  • Hi Kay. Sorry, not familiar with colloidal silver. Care to explain in detail what that is?

  • Brittany says:

    If you are using CBD as a topical spray, does the grapefruit test still apply?

  • Hey Brittany. Thanks for the question. No, as a topical product, you don’t need to worry about CBD drug interactions. We always recommend still checking with your doctor.

  • Vicki Kirby says:

    I have a question, I’m on blood thinners for over twenty years, why would someone stop taking warfarin? I have a heart valve and a stroke with poor comprehension!

  • Vicki please speak with your doctor. This website is not a source of medical advice or information. Thank you for understanding.

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