Have you ever wondered, or even feared, if taking CBD along with your usual prescription drugs can cause any undesirable effects? Have you experienced any such effect recently?
And do you think these reactions were due to taking CBD, which is a cannabis-derivative, along with pharmaceutical drugs, which are predominantly chemically constructed medications?
Well, cannabidiol (CBD), or any cannabinoid for that matter, react with our body in a very different manner than an average pharmaceutical drug. In fact, it follows quite a different pathway compared to conventional medications, making it a largely safe substance, both independently and with most other medicines.
So much so, the World Health Organisation (WHO) had in November 2017 declared that CBD has a “good safety profile”, adding that there were “no public health-related problems associated with the use of pure CBD”.
Nonetheless, CBD does sometimes require some of the same agents as your prescription drugs to break down within the body and disperse into your bloodstream in order to reach its target. You must bear in mind, that CBD, although a plant extract, is after all a chemical compound.
This is why it is necessary to know which drugs can and will interact with CBD, and when you should stay away from either CBD or these drugs.
Which drugs shouldn’t be taken with CBD?
Admittedly, and backed by scientific research, CBD is indeed a safe substance, having many therapeutic benefits. However, certain drugs do interact with CBD – and CBD users should be aware of these for their safety.
Moreover, these interactions vary depending on the purity and quality of the CBD extract, as well as its delivery method. But, how that happens will be discussed later. For now, let’s first look at all the medications that can possibly interact with CBD.
As per a Drug Interaction Table [1], created by the Indiana University Department of Medicine, drugs that may generally interact with CBD due to its impact on a specific liver enzyme include:
- Steroids
- HMG CoA reductase inhibitors
- Calcium channel blockers
- Antihistamines
- Prokinetics
- HIV antivirals
- Immune modulators
- Benzodiazepines
- Antiarrhythmics
- Antibiotics
- Anesthetics
- Antipsychotics
- Antidepressants
- Anti-epileptics
- Beta-blockers
- PPIs
- NSAIDs
- Angiotensin II blockers
- Oral hypoglycemic agents
- Sulfonylureas
Not only is this list not exhaustive, this list only includes some categories of medications that need a certain liver enzyme to break down in the way CBD does when ingested.
Again, there are certain medications that interact with CBD in a completely different way. Let’s discuss some of these categories in more details:
Heart & cardiovascular medications
CBD can potentially interact with many heart medications, like statins (cholesterol-reducing medications) and beta-blockers (or β-blockers, used to treat abnormal heart rhythms and often administered after heart attacks.
In the case of beta-blockers, the reason for its interaction is that CBD has been found to possess blood-pressure reducing properties. This interferes with the work of β-blockers on our body.
CBD, when ingested or inhaled, keeps some of the body’s systems busy to help it reach the bloodstream, thus obstructing the cholesterol medications from doing their job. This leads to these medications being stored in the body for a longer period that can prove dangerous to the patient.
Some examples of heart medications that can interact with CBD are:
- Pitavastatin (Pravachol)
- Ticagrelor (Brilinta)
- Atorvastatin (Lipitor)
- Nifedipine (Adalat, Procardia)
- Celiprolol (Celicard)
- Quinidine
- Talinoloa
- Clopidogrel (Plavix)
- Carvedilol (Coreg)
- Amiodarone (Cordarone)
- Valsartan (Diovan)
Blood pressure medications (calcium channel blockers)
Like we mentioned earlier, medications used to treat blood pressure and abnormal heart rhythms, like calcium channel blockers and blood thinners, like warfarin, can be profoundly impacted by CBD’s presence in your system.
Even if some medications that don’t have these as their intended effects, but are listed as having these as possible side effects, like in the case of painkiller ibuprofen, there is a chance that they can have the same adverse effects on the body on interaction with CBD or other such plant cannabinoids.
This was proven in a study, published in the journal Epilepsy & Behavior Case Reports in 2017 [2] by some researchers at the University of Alabama at Birmingham, United States.
By reducing the body’s capacity to break down blood thinners, CBD ultimately intensifies their effects and durability, as they remain in the body for a much longer period. In effect, this process leads to the risk of bleeding.
Similar medications that may interact with CBD are:
- Verapamil (Calan, Isoptin, Verelan)
- Diltiazem (Cardizem)
- Isradipine (DynaCirc)
- Torsemide (Demadex)
- Felodipine (Plendil)
- Amlodipine (Norvasc)
Sedatives & antidepressants
Although not all antidepressants interact with CBD, the effects of benzodiazepines (or ‘benzos’) that are often used for treating anxiety, depression, insomnia, panic attacks, and nausea, may be enhanced or even intensified due to the presence of CBD in the system.
Not only does CBD tend to slow down their activity, leading to these medications remaining in the bloodstream for a longer period, but cannabinoids, like CBD and THC themselves, also have certain sedative-like properties [3].
This is especially true for benzodiazepines, such as alprazolam (Xanax) and diazepam (Valium).
Although this may not seem fatal, their interaction may lead to certain complications. So far, research on the extent of their potential additive effects leaves much to be desired.
Another anti-anxiety medication Buspirone (BuSpar) that is used to treat generalized anxiety disorder and often prescribed alongside other antidepressants is also not advisable to take with CBD. This medication, like many other drugs, requires the same liver enzyme that is engaged by CBD to break down in the stomach. Yet another antidepressant that has a high probability of interacting with CBD is Clomipramine (Anafranil).
Some common benzodiazepines that may interact with CBD:
- Alprazolam (Xanax)
- Diazepam (Valium)
- Triazolam (Halcion)
- Pitavastatin (Pravachol
- Quazepam (Doral)
- Midazolam (Versed)
- Triazolam (Halcion)
Antibiotics
A group of antibiotics, known as fluoroquinolones, which are often used to treat respiratory and urinary tract infections, has a high risk of interacting with CBD. They include:
- Ciprofloxacin (Cipro)
- Levofloxacin (Levaquin)
- Gemifloxacin(Factive)
- Norfloxacin (Noroxin)
- Moxifloxacin(Avelox)
- Ofloxacin (Floxin)
Epilepsy & anti-seizure medications
Most studies have generally shown that there is either no effect or there is a positive reaction on patients when they clubbed CBD with anti-seizures medications. However, certain participants have been seen to experience negative side effects, like diarrhea, vomiting, fatigue and increased body temperature, when the medication in question was Carbamazepine (Tegretol). [4]
Meanwhile, inhibiting the body’s ability to metabolize anti-epileptic drugs like Clobazam (a benzodiazepine-derivative, sold under names like Frisium, Urbanol, and Onfi) can also lead to more aggressive seizures, due to high blood concentrations of clobazam and norclobazam (a clobazam derivative).
Chemotherapy
CBD has also been found to interact with several chemotherapy drugs. Like in case of most other drugs, CBD inhibits the body’s ability to process these drugs, often leading to a toxic buildup in the bloodstream.
Some common chemotherapy drugs that strongly interact with CBD are:
- Etoposide (VePesid, Eposin, Etopophos)
- Methotrexate
- Paclitaxel (Taxol)
Although CBD does alleviate pain associated with cancer and THC inhibits growth and multiplication of cancer cells, if it is taken along with chemotherapy treatment, the type and dosage of the cancer medication used must be adjusted keeping CBD into account.
Some more medications that may interact with CBD are…
- Lovastatin (Mevacor) [Cholesterol treatment]
- Ketoconazole (Nizoral) & Itraconazole (Sporanox) [Antifungal medications]
- Troglitazone and Methylprednisolone [Anti-inflammatory drug]
- Fexofenadine (Allegra) & Terfenadine (Seldane) [Anti-histamines]
- Simvastatin (Zocor) [Cholesterol and lipid-lowering medication]
- Artemether (Artenam, Paluther) & Halofantrine [Malaria medications]
- Viagra (Sildenafil)
About CBD, Cytochrome P-450 System & interactions
CBD, like any other chemical compound, does interact with other chemicals that the body may be exposed to. While it has many therapeutic effects, its risk of adversely interacting with your current medication puts you at all kinds of risks.
We had earlier mentioned, on several occasions, in this article that liver enzymes needed to metabolize most drugs are also engaged by CBD to break down. This is usually the case when you ingest CBD in the form of capsules or edibles (which is one of the most convenient ways to take any drug). Unless and until your digestive system metabolizes the substance, it cannot reach your bloodstream.
The liver enzyme, or rather the group of enzymes, in question, which is, in fact, responsible for metabolizing all drugs and toxins introduced into the body, is known as Cytochrome P450 (CYP450). Since CBD also requires this enzyme to break down, CYP450’s ability to process other drugs slows down.
This may lead to a range of undesirable effects, depending on the drugs’ intended effects (and side effects).
Grapefruit & CBD: Similarities in Interactions
Anyone who would have looked up drug interactions and CBD would have come across a comparison between this cannabinoid and grapefruit or grapefruit juice. It may seem uncanny to you, but the fact is that they both work in a similar fashion.
Grapefruit or its juice inhibit the CYP450 enzymes from processing the pharmaceutical drugs first. This is why any drug whose effects are inhibited by grapefruit is often unwise to take along with CBD.
Some of the common drugs that interact with grapefruit [5] and its extracts are:
- alprazolam
- amiodarone
- atorvastatin
- carbamazepine
- cilostazol
- clarithromycin
- colchicine
- dronedarone
- erythromycin
- felodipine
- fentanyl
TIP: In case you’re wondering if CBD will interact with your current medication, look for the warning that tells you to avoid grapefruit on the medicine package. This is an indication that CBD could also interfere with your prescription drugs.
CBD’s delivery method determines its risk of interaction
We have established that CBD, when administered through the digestive system, i.e. ingested and reaches your stomach, can interact with certain drugs that require CYP450 to break down.
Then, does it mean that using CBD in any other form is safer with no risk of interaction?
CBD oils and tinctures that are administered sublingually are mostly absorbed directly into the bloodstream. The remaining amount that’s swallowed goes through the digestive system, thereby leaving scope for interaction with your current medication.
Besides, they may also interact with medications, used as sedatives or anti-depressants, and those that affect your blood pressure or blood viscosity.
Inhalable CBD bypasses the digestive route and enters the bloodstream through the alveoli of the lungs. In this process, however, CBD interacts with CYP1 enzymes, a group of enzymes that fall under the CYP450 family, leading us to believe that there is still a possibility of a drug interaction.
Since the topical application of CBD takes the substance from the site of administration directly to the affected site it has the least risk of interacting with other drugs. It addresses the localized issues (skin, joint, etc.) right away on the tissue-level, without having to go through any other organ or the bloodstream, thus removing any risk of interacting with any other drug.
However, it cannot be said with certainty that the cannabinoid will not enter the bloodstream at all, as the surface of the body is covered by innumerous blood vessels. The concentration of the substance and its volume may play a role in how much, if any, enters the blood vessels.
While the topical method of delivery may be the safest, ingestion (oral consumption) of CBD is the riskiest method, as far as drug interaction is concerned.
Our Takeaway: Consult your doctor
CBD certainly has many health benefits, ranging from relieving stress to helping manage depression and anxiety, from alleviating acute pain to treating chronic pain, even those associated with cancer and chemotherapy, from combatting insomnia to dealing with attention deficit, and even helping calm seizures associated with epilepsy.
However, CBD is only a new drug to most of us. People, who are currently on other drugs, need to keep taking them. Not only are we used to their effects and how they may adversely affect us (side effects), we are also advised by our doctors to be consistent with our dosage. For a layman, it is not wise to change or quit their prescription drug on a whim or some research done elsewhere.
Besides, we have also pointed out in this article the several ways the use of CBD can interfere with our current medication, leading to some undesirable effects, sometimes even accompanied by some dangerous consequences.
Given all these factors, we would advise our readers as well as all CBD users to first consult a doctor, preferably someone with prior experience in treating with cannabinoids, before deciding to pick up their first bottle or cartridge of CBD oil.
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Research citations:
- Drug Interactions Flockhart Table ™; Indiana University School of Medicine; Department of Medicine Clinical Pharmacology; https://drug-interactions.medicine.iu.edu/Main-Table.aspx
- An interaction between warfarin and cannabidiol, a case report;
Epilepsy & Behavior Case Reports; Oct 12, 2017; Leslie Grayson, Brannon Vines, Kate Nichol, Jerzy P Szaflarski, and for the UAB CBD Program; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5789126/
- Cannabidiol in Anxiety and Sleep: A Large Case Series; Permanente Journal; Jan 7, 2019; Scott Shannon, MD, Nicole Lewis, ND, Heather Lee, PA-C, and Shannon Hughes, PhD; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6326553/
- Cannabidiol–antiepileptic drug comparisons and interactions in experimentally induced seizures in rats; Journal of Pharmacology and Experimental Therapeutics; April 1977; Consroe P, Wolkin A; https://www.ncbi.nlm.nih.gov/pubmed/850145
- Drug Interactions with Grapefruit Juice; Medically reviewed by L. Anderson, PharmD Last updated on Feb 13, 2018; https://www.drugs.com/article/grapefruit-drug-interactions.html
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