Most Common CBD Drug Interactions and Side Effects

CBD Drug Interactions

It’s perfectly natural to be concerned about possible CBD drug interactions and their side effects.

Seeing how 46% of Americans have taken one or more prescription drugs in the past 30 days and that 22.2 million have said they have used cannabis at least once in the last month, there’s bound to be some overlap between the two.

That’s why reading up on all the essential information regarding how CBD and other medications interact in the human body should be a number one priority when consuming weed.

What Is CBD?

Before we get into marijuana drug interactions, let’s talk a little about CBD.

CBD (cannabidiol) is a phytocannabinoid found in cannabis along with 113 other cannabinoids.

When people say that CBD is everywhere, they mean it. CBD can be found in consumer products like cosmetics, drinks, even food. Other uses for CBD oil include relief for countless medical conditions, like migraines, autism, mental disorders, and MS, to name but a few.

Another factor that contributes to the popularity of CBD is the fact that, unlike THC, it is non-psychoactive. Meaning, there is no such thing as a CBD high.

How Can CBD Oil Interact with Medications?

CBD can inhibit the activity of cytochrome P450 — a family of liver enzymes that metabolize toxins and certain medication (CBD included) that enter the human body. CBD can temporarily block the regular function of these enzymes, causing some drugs in the system to be broken down more slowly, thereby increasing the amount (and potency) of these medications in the system, as well as the risks of possible side-effects and medication interactions.

In certain cases of drug interactions with cannabis, there can be some serious complications, like bleeding and hemorrhages, and even respiratory system issues.

In other instances, CBD can also speed up the performance of some of the enzymes in this group, which in turn speeds up the metabolism of certain drugs. What does this mean? The levels of these drugs in the system are lower and, thus, they are less effective.

Cannabidiol is not the only one blocking CYP450. Grapefruit and grapefruit juice also exhibit the same effects as drug interactions with marijuana do. In fact, CBD is just as powerful as bergapten — the most potent inhibitor of liver enzymes found in grapefruit. The main difference between the two is that grapefruit warnings are listed on most medications, unlike CBD. So, if you see that a particular medication should not be used with grapefruit, it’s a safe bet that you shouldn’t use it with CBD either.

Other substances like watercress and St. John’s Wort might produce a similar effect when combined with certain drugs.

What Drugs Should Not Be Taken with CBD?

The list can get quite extensive as almost 60% of the drugs on the market are broken down in the body through the liver, i.e., through CYP450. Nevertheless, the most common medication that should not be used in unison with CBD (pure or full-spectrum) include:

  • Anti-epileptic and anti-seizure drugs
  • Statins
  • Blood thinners
  • Antidepressants
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Muscle relaxants
  • Sedatives (benzodiazepines)
  • Beta and calcium channel blockers
  • Chemotherapy medication

Consulting a professional on what medications interact with CBD oil is crucial before consuming any of these drugs and cannabidiol. This list does not include all the drugs that interact with cannabidiol. Nor does it mean that a combination of any of these types of medication will cause issues when taken with CBD.

The severity of the reaction also depends on the amount of time the drugs have been in your system as well as some pre-existing medical conditions or allergies.

CBD Drug Interactions List

Anti-Epileptic or Anti-Seizure Drugs and CBD

Drugs used to treat epilepsy and seizures mixed with cannabidiol can lead to severe consequences as a result of these medications interacting with marijuana.


This is particularly true of clobazam, which can have serious interactions with CBD. Clobazam (Onfi) is used in combination with other medicines to control seizures. Particularly the ones caused by Lennox-Gastaut syndrome, a rare form of epilepsy among children.

This drug is metabolized by the liver enzymes that CBD blocks and can result in major drug interactions with CBD oil. Simply put, when used together, the effects and side effects of clobazam increase, which could lead to many adverse effects, such as dizziness, constipation, drowsiness, breathing problems, and even depression and suicidal thoughts.


Valproate is the other of the two drugs that are known to cause major interactions with CBD. In addition to epilepsy, valproic acid is also used to treat some mental conditions and migraines.

Valproic acid could cause serious, even life-threatening liver damage, usually within the first six months of therapy. This medication also has some serious CBD hemp oil drug interactions. The combined use of this medication and cannabinoid oil could increase the risk of liver damage.


Another anti-seizure drug that is known to interact with CBD is eslicarbazepine (Aptiom), although less severe than the previous two. It can be used alone or with other drugs to treat focal seizures (seizures that affect only one hemisphere of the brain) in adults and children by reducing the number of attacks.

Eslicarbazepine can lead to moderate drug interactions with CBD. Cannabidiol use could slow down the metabolism of eslicarbazepine in the body and thus increase the potency of the drug in the system, but only by a small degree.

Topiramate and Zonisamide

CBD also has a similar effect on topiramate (Topamax) and zonisamide, which are used to treat epilepsy. The former is also said to increase some CBD oil effects, like stress reduction. It could also enhance some CBD oil side effects, such as drowsiness and sleepiness.

CBD and Statins

Statins are drugs that reduce cholesterol levels in the body and in that way help reduce the risk of heart attacks and strokes.

Atorvastatin and simvastatin are some of the most commonly prescribed cholesterol-lowering medications. Used in combination with a proper diet, atorvastatin lowers bad cholesterol and fats in the body and “improves” HDL, or good cholesterol in the blood.

Statins are known to interact with CBD. Frequent use of both can lead to serious cannabis drug interactions. In atorvastatin interactions with CBD, CBD oil use can increase the serum concentration of atorvastatin and simvastatin, which results in them staying in the system for longer and causing dangerous accumulation. Unlike these two drugs, other statins like pravastatin and rosuvastatin are not proven to be affected by cannabidiol.

Blood Thinners and CBD

One drug on the blood thinners list that interacts with cannabidiol is warfarin, used to treat existing blood clots and prevent new ones from forming.

Warfarin is metabolized by the CYP2C9 enzyme, the same one that CBD is said to block. According to the CBD drug interactions list, the combination of these two drugs is particularly harmful as it can lead to severe bleeding and thrombosis.

Other blood thinners such as rivaroxaban and apixaban increase the likelihood of side effects, while some medications like heparin and edoxaban have not shown any significant interaction with CBD.

Antidepressants and CBD

Antidepressants are prescribed for a variety of psychiatric and psychological disorders from OCD and  ADHD, to stress and anxiety. The effectiveness of some antidepressants, like SSRIs (Prozac and Zoloft) and SNRIs (Effexor and Pristiq) could be reduced due to CBD oil drug interactions.

Others like MAOIs (Nardil and Marplan) and TCAs (Amitriptyline and Anafranil) could result in more serious damage and should not be taken together with CBD. In addition to increasing the sedative effect of cannabidiol, they could also cause hypertension and tachycardia, as well as enhance the side effects of CBD oil.

Buspirone is an anti-anxiety medication, commonly prescribed with antidepressants, used to treat generalized anxiety disorder. This drug also comes with warnings of severe CBD drug interactions.

The good news is that CBD and antidepressants have many of the same beneficial effects. In fact, CBD oil benefits patients suffering from sleep issues and anxiety and could one day replace the use of antidepressants altogether as cannabidiol has less side effects than these medications.


The use of nonsteroidal anti-inflammatory drugs (NSAIDs) can also be affected by CBD consumption. These drugs are processed by the liver, so there are possible drug interactions with CBD hemp oil.


Diclofenac is primarily used to treat pain and inflammation. Because it reduces the substances in the body that cause inflammation, it can also be beneficial for spondylitis, acute migraines, headaches, as well as menstrual cramps. Diclofenac interactions with cannabidiol can lead to liver issues, as well as bleeding complications, especially after frequent use.


Naproxen, on the other hand, is prescribed to treat headaches, tendonitis, toothaches, as well as joint stiffness caused by arthritis and gout. Naproxen is also used in some cold medicine, which calls for caution due to existing weed drug interactions when combining CBD and flu drugs that contain naproxen. Unlike diclofenac, naproxen is more commonly used to treat chronic conditions as it does not work fast enough for acute pain.

Also, CBD and naproxen interactions can result in prolonged effects of the medication. In this case, some of the side effects include nausea, heartburn, and reduced blood pressure.


Ibuprofen (Advil) is one of the most commonly used OTC medications for pain relief. It is an NSAID that reduces inflammation and pain levels in the body.

When it comes to CBD and ibuprofen interaction, things get a little tricky. Ibuprofen is mostly metabolized by the kidneys, so it shouldn’t pose a risk when taken with CBD. Also, it is not one of the medications known to have adverse effects when combined with grapefruit, so it’s safe to assume that the same goes for CBD.

Is ibuprofen a blood thinner? Yes, it may not be as potent as aspirin, but it can still affect blood clotting time, especially if it has been in your system for a while.

Now, you may be thinking: can I take ibuprofen with CBD oil without experiencing any side effects? The answer is “yes,” as long as the doses are right and spaced out properly, as indicated on the medicine’s bottle. In that case, there shouldn’t be any major interactions between CBD and Advil.

Bear in mind, though, that Advil is a medication people usually take more than once a day. You might want to avoid possible side effects from frequent use of ibuprofen and cannabidiol.

Muscle Relaxants and CBD

Muscle relaxants, such as cyclobenzaprine and tizanidine, can also cause medical marijuana drug interactions.

Cyclobenzaprine (Flexeril) is used as a short-term treatment for muscle spasms, whereas tizanidine (Zanaflex) is used to treat muscle spasms caused by multiple sclerosis or spinal cord injuries. Both block nerve impulses, or pain sensations, sent to the brain.

According to the drug interaction checker, cyclobenzaprine interactions with CBD are classified as moderate. A Flexeril-CBD oil combo could increase the side effects of the medication, such as dizziness, confusion, and a lack of concentration. The same is true of cannabidiol and tizanidine interactions.

Sedatives and CBD

Moderate cannabis and drug interactions are possible when mixing sedatives and CBD oil.

Sedatives can include benzodiazepines, such as alprazolam (Xanax), lorazepam (Ativan), diazepam (Valium), morphine, and others, as well as sleep aids like zolpidem (Ambien).

Sedatives are drugs that slow down brain activity and help a person relax. They are usually prescribed for anxiety and sleep disorders.

Like these drugs, THC and CBD also have a sedative effect on the body. The exact relationship between cannabinoids and sedatives, as well as potential CBD drug interactions are not known, however, higher doses of CBD and benzodiazepines could cause an additive effect, i.e., cannabinoids might increase the effects of the sedatives.

Beta Blockers and Calcium Channel Blockers and CBD

Beta-blockers (Inderal, Sectral) and calcium channel blockers (Norvasc, Cardizem) are used to treat angina, blood pressure, tachycardia, and migraines. Interactions between CBD oil and beta and calcium channel blockers could result in lower blood pressure that might cause the user to feel weak, lethargic, and dizzy. In rare cases, marijuana and drug interactions could lead to users fainting or even going into shock.

CBD and Chemotherapy Medication 

One of the benefits of cannabidiol is the use of CBD oil for cancer, particularly in combating the side effects of cancer treatment, such as nausea, vomiting, and weight loss.

CBD can prolong the time it takes to process certain chemotherapy drugs, such as etoposide and methotrexate and could lead to toxic accumulation in the body as a result of cannabis drug interactions.

Opioids and CBD

Opioids are narcotics used to relieve pain. Some of the most commonly used pain-killers include fentanyl, oxycodone, morphine, and codeine. While it was believed that opioids and CBD increased feelings of drowsiness when combined, new research shows that CBD and opioids use can actually enhance the effects of CBD oil. Also, cannabidiol could be used instead of opioids because of lower-risk CBD oil side effects.

Drugs That Decrease the Benefits of CBD Oil

Although there are little or no drug interactions between CBD oil and antibiotics, rifampin (Rifadin, Rimactane) is known to decrease the effect of CBD on the body. Carbamazepine (Tegretol), an anticonvulsant, and prednisone, a corticosteroid, have the same effect on cannabidiol.

CBD and Other Herbs and Supplements

When using certain sleep-inducing herbs, like calamus, poppy, sage, or supplements, such as  L-tryptophan and melatonin, with cannabis, a person could feel even more sedated or sleepy. This is not necessarily an adverse effect if you are going for it. However, it can impair day-to-day activities and cause discomfort and inconvenience.

How to Lower CBD Drug Interactions?

The severity of drug interactions with cannabidiol can vary. First and foremost, it depends on the manner in which CBD is taken. It goes without saying that when used orally, CBD is most likely to interact with other medications. If it is applied topically, for instance, a CBD cream or body lotion, chances of interactions are lower.

Another important factor is the right CBD oil dosage. Make sure to always use the dosage indicated on the medicine’s bottle and the recommended amount of CBD to avoid any possible drug interactions with marijuana.

And remember, when in doubt, consult a professional. That’s what they are for anyway.

Bottom Line

Like everything else in life, you have to take the bad with the good. The same goes for CBD. Although it can be extremely helpful, it doesn’t come without risks. The best thing to do is exercise caution and carefully read up on all the CBD drug interactions and possible side effects to avoid any potential complications.


How long does CBD stay in your system?

It varies.  Usually it is three to five days, however, it depends on how it is consumed and what kind of CBD oil you are using. In terms of combining CBD with other drugs, some users recommend a two-hour waiting period as the safest way to avoid adverse reactions. Still, this method has not been tested or proven yet.

Does CBD interact with medications?

Like all other medications, CBD is also known to interact with certain drugs. Sadly, there isn’t one rule that fits all cases. Not every drug produces the same effects or reacts the same way when in contact with other drugs. That being said, users must be careful when combining medication, especially with drugs of which the full impact is not yet known.

What drugs should not be taken with CBD in the UK?

Although they might have different brand names, the active components are the same and the way CBD interacts with them is the same everywhere in the world.

It is best to consult your physician before taking any kind of medication, especially if you are thinking of using several drugs at the same time. Another good idea is to ensure that you buy your CBD from reputable sources that offer certified quality and third-party testing.

What medications does CBD interfere with?

CBD is known to block the work of cytochrome P450, a group of liver enzymes that are responsible for metabolizing nearly 60% of all medications, both prescribed and OTC. This is particularly true of drugs that have similar health effects as CBD, such as antiepileptic drugs, NSAIDs, and sedatives.

Is marijuana a depressant?

Even though it is known to produce similar effects, marijuana is not classified as a depressant. Depressants affect GABA receptors in the brain, while marijuana impacts dopamine levels in the body.

Does CBD oil interact with co-codamol?

Co-codamol is a combination of paracetamol and codeine. It is commonly prescribed to relieve pain caused by headaches, muscle aches, migraines, and toothaches.

It is usually taken along with other painkillers, such as ibuprofen and aspirin. So far, there haven’t been any indications of interactions between CBD and paracetamol. This doesn’t mean that they cannot interact. Hence, if you are experiencing any issues, you should consult a medical professional. Codeine, on the other hand, is an opioid, which also might have some minor interactions with cannabidiol.

Does CBD have any drug interactions with cannabis-based pet products?

CBD pet products, such as oils and treats, are well-tolerated by pets and are not known to cause any serious issues. However, just like with humans, sometimes cannabidiol can interact with certain medications. Always read the label on pet products before you give your cat or dog any kind of medication. Try to buy your CBD products from a reputable seller and check the CBD content in the products themselves. The most important thing when it comes to CBD oil for dogs drug interactions is to ensure that the dosage is right as smaller doses have less potent effects.

6 thoughts on “Most Common CBD Drug Interactions and Side Effects

  1. I am taking paroxetine, pregablin, and atorvastatin, I have heard how good the cbd cream is, and was thinking if using it for my joint pain, is it safe to.


    1. Hello Pauline! Here is a piece of advice from our Dusan Goljic, Pharm.D.:
      It is perfectly safe to take your cream alongside these medications. The cream acts topically, which means that it has very low absorption levels, thus cannot interact with any medications in the bloodstream.
      However, in order to absolutely eliminate this possibility from the equation, it is of prime importance to use your cream on the limited joint area in thin layers, as stated on the label.
      If you develop any local unease, it is likely to skin sensitivity.
      If you have any other remarks, please consult your healthcare professional.

  2. HELP!
    I am receiving conflictig advice on the use of CBD oil, some say there is no interaction with my current medication, others say yes there is and others to leave a 4 hour gap between any medication and CBD oil.
    Who is correct?
    I am taking:
    Bumetanide 1mg tablets – take one each morning
    Fluticasone 400microgram/unit dose nasal drops – 1-2 times daily
    Simvastatin 40mg tablets – take one at night
    Citalopram 20mg tablets – Take one daily

    1. Hello Roy! I suppose all the advice came from doctors who prescribed these medications. Here is what Dusan Goljic, Pharm.D., our very own professional, has to say:
      There is a low probability of interaction between your medication and CBD oil. However, it is best not to take all of them concomitantly, due to the possibility of increased elimination of the CBD oil.
      Therefore, the best practice is to take your dose of CBD oil during midday. Approximately 4 hours after bumetanide and citalopram.
      We hope we’ve been of some help to you.

  3. Would it be safe to take CBD for knee pain when I am taking the following meds:
    Simvastatin 40MG
    Levothyroxin 88mgg
    Triamt/HCTZ 37.5 25mg
    Pantoprazole 20mg
    Lisinopril 10 mg
    Thank you for helping me.

    1. Dear Velma,
      When we consider the basic pharmacology, there is low interaction probability with oral CBD products.

      However, due to the intense dosing schedule that you’re already on, we would not recommend complicating it further with systemic (oral) products.
      If you’re reaching for that kind of product, you’ll need to consult your physician.

      Considering that, we would recommend that you skip the oral CBD product and use a topical one, in the form of emulsion or creme, with a high CBD content. In that case, the interactions are truly minimized, or possibly non-existent.

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