CBD may interact with certain medications.

Can CBD Interfere with Your Medications?

By Jenny Menzel, H.C.  

Just under 50% of Americans regularly take at least one prescription drug, according to the Centers for Disease Control and Prevention (CDC), making the topic of safely combining cannabidiol (CBD) with medications paramount. After ingesting CBD, the cannabis compound interacts with receptors throughout our endocannabinoid system; an intricate network of cannabinoid receptors inside our body that help regulate our immunity, mood, and metabolism.

Although gentle in nature, CBD is a potent cannabinoid capable of affecting our bodies, and anything we put into it. As science continues to uncover positive effects cannabinoids have on our health, early research discovered a potential negative impact CBD may have by interfering with certain medications. In this article we will look at the CBD properties causing this interference, as well as specific medications that are contraindicated with cannabidiol. 

What You Should Know Before Mixing CBD With Medications

CBD Inhibits Liver Enzymes

Cytochrome P450 (CYP450) is a family of liver enzymes that metabolize certain medications, breaking them down for its intended use and for elimination from the body. Because CBD inhibits CYP450, medications that require these enzymes may not metabolize properly, making the medicine pass through the body too quickly or not quickly enough. This interference not only can render the medication ineffective, resulting in undertreatment of the condition the medication was prescribed for — it can turn the medicine toxic by building up in the body from improper elimination, setting the stage for a chance of increased side effects. 

Rule of Thumb: If you’ve ever been advised to not drink grapefruit juice with a medication, you should probably avoid combining that medication with CBD. Like CBD, grapefruit juice is a known CYP3A4 inhibitor — one of over 50 CYP450 enzymes. In fact, "the grapefruit effect" is a phrase commonly used to describe the well-documented contraindication between grapefruit juice and CYP450 substrates (drugs or compounds metabolized by CYP450). While CBD hasn’t been as extensively studied as grapefruit juice, recent research shows CBD to be the most potent CYP inhibitor of all phytocannabinoids.

Check with your doctor before combining CBD with any medication. Until more studies on CBD are conducted that suggest otherwise, it’s a safe bet to avoid using CBD with any CYP450 substrates.

Medications that Don’t Mix Well with CBD

If you take medications, consult with your doctor before adding CBD.

Because chemistry is complex, the severity of drug interactions vary. This is why checking with your practitioner before adding CBD to your regimen is of utmost importance. Below are drugs contraindicated with CYP450 inhibitors due to a higher risk of interference. Use this brief list as a starting point to determine if merging your medication with CBD is okay.

1. Blood Thinners. CBD is deemed generally safe, with some studies noting its heart-healthy ability to reduce blood pressure. Nonetheless, its enzyme-inhibiting quality may cause some blood thinning drugs to build up in the liver, increasing the risk for unwanted side effects. Data reviewed in Basic & Clinical Pharmacology & Toxicology found an increase in subjects’ INR values (the time it takes your blood to clot) when Warfarin was combined with cannabinoids, inspiring warning against using the two together. Other blood thinners that may require similar caution when using CBD are Apixaban, Rivaroxaban, and Heparin. 

2. Anticonvulsants. Used to treat epileptic seizures, anticonvulsant drugs like Clobazam, Rufinamide, Topiramate, Zonisamide, and Eslicarbazepine were found to have significant contraindication with CBD. More evidence may be needed to draw firm conclusions, and until then, it is best to consult with a doctor before taking CBD while on anti-seizure medications — in spite of its positive reputation as a natural anticonvulsant.

3. Pain medications. Sedating like opiates and Gabapentin prescribed for pain conditions require CYP1A2 enzymes to metabolize. Though studies show CBD inhibits CYP1A2, combining CBD with drugs with sedative qualities have yet to be documented as dangerous duos. But that doesn’t mean drug interactions don’t occur. CBD acts as a sedative in high doses, and when combined with a drug that also induces sedation, it's more likely to pack on an additional sedative quality, make you feel drowsy, and less alert. 

The Bottom Line

Body chemistry is complex, making the interactions our body has with engineered pharmaceuticals (and anything we ingest) difficult to understand. Even though science has shown CBD to have many health benefits, the organic compound is not exempt from negatively impacting the body when combined with other substances. The list of contraindicated medicines provided in this article is far from exhaustive, and a trusted doctor with knowledge of your personal medical history should be consulted before adding CBD to your daily routine — especially if you are taking any medications.

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Jenny Menzel, H.C., is a Certified Health Coach and branding specialist for various alternative healthcare practices, and volunteers her design skills to the annual grassroots campaign, the Lyme Disease Challenge. Jenny was diagnosed with Lyme in 2010 after 8 years of undiagnosed chronic pain and fatigue, and continues to improve by employing multiple alternative therapies, including Āyurveda, Chinese Medicine and Bee Venom Therapy.

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