How to counsel patients on CBD use with blood thinners

CBD use is growing in the U.S., so it’s important to know how to counsel patients on certain meds, like blood thinners

The use of cannabidiol (CBD), whether in oils, gummies, or creams, is rapidly growing in the United States. In 2022 alone, the consumer market size for CBD reached around $16 billion and is expected to nearly quadruple by 2032. 

Although studies are ongoing, many people find that CBD helps with general ailments, such as minor pain and trouble sleeping. CBD may have several benefits for health, but that doesn’t mean it’s entirely safe to use, especially if patients have other medical conditions or are taking other medications. Taking CBD and blood thinners, in particular, could lead to serious drug interactions and adverse effects. 

When it comes to herbal supplements and alternative oral treatments, pharmacists can be a guiding voice for patients who have concerns about CBD with blood thinners. Continue reading to learn more about how CBD affects blood thinners and how to counsel patients who may be taking both. 

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The effects of CBD on the blood

Cannabidiol is a cannabinoid found in Cannabis sativa, along with other cannabinoids such as tetrahydrocannabinol (THC) and cannabinol (CBN). However, CBD does not have the psychoactive effects that THC has—and instead may have holistic health benefits for pain, anxiety, and sleep, among others. 

Regarding its effects on the blood, CBD does not have any significant effects on blood clotting. Instead, CBD has been found to act on the blood vessels, causing vasodilation or widening of the blood vessels. While this effect may improve blood flow, it does not affect the underlying causes or risks associated with blood clots.  

Blood clots are generally formed due to a complex process involving platelets and clotting factors in the blood. The main concern with blood clots is that they can obstruct blood flow, leading to problems like deep vein thrombosis (DVT), pulmonary embolism, or stroke. Treatment for blood clots often involves the use of anticoagulants or blood thinners to prevent the formation of new clots and help the body break down existing clots.

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RELATED: Are CBD products safe for people taking prescription medications? 

Can you take CBD with blood thinners?

It is not generally safe to take CBD and blood thinners, as CBD can affect the metabolism of some blood thinners through its effects on CYP enzymes. Specifically, CBD can act as a CYP inhibitor, which can slow or block the metabolism of a CYP-metabolized blood thinner, leading to increased drug levels and an increased risk of bleeding. Although CBD is metabolized by several enzymes of the CYP450 liver enzyme system, it also acts as a strong inhibitor of those enzymes. 

Many patients might be unaware of this drug interaction and find themselves in a potentially dangerous situation. For example, patients who take blood thinners like warfarin for atrial fibrillation may also be taking CBD to relieve anxiety or pain. However, this combination could lead to an increased risk of bleeding events. 

Case study of CBD interactions with a common blood thinner

One case study found that CBD linearly increased the INR value in a patient on warfarin treatment. The CBD dosage was gradually increased for the first three visits while the patient maintained a dosage of 7.5 mg of warfarin daily. 

The increased dosage of CBD with warfarin led to a dangerous increase in INR and an increased risk of bleeding. Luckily for the patient, the drug interaction did not lead to bleeding complications because the healthcare provider had quickly adjusted the warfarin dosage upon noticing the change in INR. 

Blood thinners to avoid or use with caution with CBD

Blood thinners that are metabolized by the liver’s CYP enzymes can interact with CBD and cause an increased risk of bleeding events. These include oral anticoagulants apixaban, rivaroxaban, and warfarin. 

However, not all blood thinners are metabolized by the CYP450 enzymes of the liver, nor do they change the activity of these enzymes. These include dabigatran, edoxaban, and heparin. Taking CBD with these blood thinners is unlikely to lead to a drug interaction that causes an increased bleeding risk. 

Precautions to take when using CBD with blood thinners

Patients should be aware of the dangers of combining CBD with a blood thinner. If you notice that a patient is taking blood thinners and mentions that they’re also taking CBD, you may want to counsel them on the potential drug interaction. Pharmacists can use their clinical judgment and expertise to measure the severity of a potential interaction and refer the patient to a healthcare provider. 

Consulting a healthcare provider

Before starting CBD while on blood thinner medications, patients should always consult their healthcare provider. They can evaluate any potential risks and help decide whether adding CBD to the patient’s treatment regimen might be appropriate. 

It’s always a good idea to understand why the patient may be interested in taking CBD in the first place. If they’re taking CBD for anxiety or sleep because their antidepressant or sleep medication isn’t working for them, the patient should consult their healthcare provider for a potential adjustment in therapy.

It’s also important to ask patients about other medical conditions and medications they’re taking, including over-the-counter drugs, supplements, and even medical marijuana, as these can all potentially interact with blood thinners and influence the treatment plan. Older patients may have a higher risk of interactions, as liver function may deteriorate over time. 

Monitoring the dosage and frequency

If patients insist on taking CBD and blood thinners, monitoring or adjusting the dosage of CBD or blood thinner may be required. 

The patient should be started on the lowest CBD dose, which may be gradually increased over time while monitoring changes in therapeutic response. The CBD dosage can be personalized according to the patient’s needs without changing the efficacy of the blood thinner or increasing the risk of adverse effects. 

Patients should also be aware of the timing and frequency of their CBD dose. You can suggest they avoid taking CBD at the same time as their blood  thinner. However, the timing of the dosage may also depend on the half-life and pharmacokinetics of the medication they’re taking with CBD. 

Understanding the dosage form and quality 

The dosage form of CBD can make a difference in determining the risk of an interaction. For example, a topical form of CBD is not absorbed into the bloodstream as much as an oral CBD tincture, for example, which means less risk of a drug interaction with blood thinners. 

In addition to understanding the dosage form, patients should use a reliable and reputable CBD product. Because CBD products are only regulated as dietary supplements, the purity and dosage of the compound in the products on the market can vary. However, Epidiolex is an FDA-approved prescription CBD drug that is standardized to treat seizures associated with Lennox-Gastaut syndrome. 

Bottom line

While the use of CBD can be beneficial for many patients, there is still a possibility of drug interactions and adverse effects, especially when combined with blood thinners. CBD can inhibit the metabolism of different blood thinners, including warfarin and dabigatran, leading to an increased risk of bleeding. However, not all blood thinners may have the same level of risk. 

Many patients might not be aware of the dangers of CBD products because they may identify CBD as a holistic, natural product that doesn’t carry the risk of harm of prescription drugs. However, pharmacists can counsel patients by educating them on the proper CBD dosage form and recommending patients always consult their healthcare provider before starting a new medication or supplement.  


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