CBD And Blood Thinners: Can You Take Them Together?

About half a million people in the UK take blood thinners to reduce the risk of blood clots that can cause life-threatening medical issues like heart attacks and strokes. The number of Americans on blood thinners is more than eight million; that number has increased substantially in recent years.

CBD use has grown rapidly in the last five years as well. In the last year alone, more than six million Britons have tried CBD products, and one-third of US adults have reportedly tried those products or used them regularly.

CBD isn’t intoxicating, and reputable sources including the World Health Organization (WHO) been widely quoted as saying that the substance doesn’t trigger serious side effects or pose serious public health risks. That information could easily make patients who take blood thinners feel comfortable trying or using CBD products without a second thought.

They should think again.

People taking blood thinners, as you’d probably guess, run an increased risk of experiencing bleeding problems or emergencies. And some — but not all — blood thinners make that risk even worse for those who are also using CBD.

Common anticoagulants like warfarin, apixaban (Eliquis), and rivaroxaban (Xarelto) are metabolised in the liver by the same enzymes that break down CBD. That could overburden the enzymes, resulting in too much blood thinner reaching the bloodstream and a greatly increased bleeding risk.

CBD has also been shown to slow or block the performance of those enzymes, potentially making the situation even worse.

Potentially dangerous interactions, however, haven’t been seen with other, less-common prescription anticoagulants like heparin, dabigatran (Pradaxa), or edoxaban (Lixinia), which aren’t metabolised by the same liver enzymes. And antiplatelet meds, another category of blood thinners, are less likely to trigger added risks when combined with CBD.

The bottom line: patients taking blood thinners should speak with their doctor or another healthcare professional before trying or using any CBD product. They may be advised to switch medications or change doses, or to avoid CBD use completely, to prevent potentially dangerous consequences.

Want to know more? Read on as we look more deeply into CBD, blood thinners, and their effects.

CBD and the Body

The first step in this discussion is understanding what CBD is and where it comes from.

All About CBD

CBD is the common acronym for cannabidiol, a plant compound found in cannabis and hemp. It’s one of more than 100 similar compounds known collectively as cannabinoids. The best-known cannabinoid, of course, is psychoactive THC (tetrahydrocannabinol). CBD and THC have similar chemical structures, but the major difference is that CBD isn’t intoxicating in any way.

Cannabidiol is extracted from hemp and not cannabis because hemp plants contain large amounts of the substance and very little THC. The level of CBD in cannabis plants is quite low, so it would be much less efficient for producers to source cannabidiol from them.

Additionally, the CBD extraction process brings other cannabidiols along for the ride. The small amount of THC in cannabidiol extracted from hemp can’t make users high. If CBD were to be taken from cannabis, however, the products manufactured with it would be psychoactive.

Cannabinoids aren’t just similar in chemical structure to each other; they’re also very similar to neurotransmitters produced inside the body called endocannabinoids. The neurotransmitters serve as messengers in a full-body network known as the endocannabinoid system (ECS), shuttling between receptors that govern an enormous number of important bodily functions.

That’s how CBD and THC deliver their effects once consumed, smoked, or vaped. The cannabinoids’ similarity to endocannabinoids allows them to interact with the ECS receptors, which regulate functions like thought, memory, appetite, sleep, pain, immunity, and inflammation.

Cannabidiol and THC deliver somewhat different effects and apparent medical benefits because of the small structural differences between them, but they each do their work by influencing different sets of ECS receptors.

They don’t take a straight-line path to those ECS receptors, though. They make either one or two stops first.

(We’ll focus on CBD from here on, since research on possible interactions between THC and blood thinners is inconclusive. It appears that THC may have, at most, a slight effect on the performance of most anticoagulants, perhaps because of the cannabidiol it contains. Only the combination of THC use with the blood thinner warfarin may be significantly problematic.)

What Happens When CBD Is Ingested

People can select from a number of CBD products, which are used in different ways.

CBD oil is either dropped under the tongue or added to food or beverages. CBD capsules contain CBD oil and are swallowed, as are CBD edible products. CBD vapes, of course, are inhaled. CBD topical products are usually blocked by the skin from entering the bloodstream, so we won’t be discussing those here.

CBD oil dropped under the tongue (sublingually) and vaped CBD are the two most efficient administration methods because the cannabidiol is immediately absorbed by either the tissues located under the tongue or by the tissues in the lungs. The CBD quickly enters the bloodstream and moves to the liver for metabolisation.

CBD products that must be swallowed, however, must take a detour. They move through the GI tract to the stomach for digestion, a process that can take between 30 minutes and two hours before the cannabidiol is absorbed in the small intestine and sent to the liver. (Not only is CBD slower acting when swallowed, but much of the cannabidiol is lost during digestion.)

No matter how it enters the body, though, CBD ends up in the same place: the liver. That’s where it’s broken down into some metabolites that deliver cannabidiol’s effects, and other metabolites that are excreted by the body. And that’s where possible interactions with blood thinners can trigger big problems.

Let’s put this discussion on hold for a moment. We’ll get back to it after a brief look at blood thinners.

The Use and Importance of Blood Thinners

Blood thinners are taken to prevent the formation of dangerous blood clots.

What Are Blood Clots?

Blood clots often form in the body. That’s normally a very good thing since clots are a natural part of the body’s healing process. They stop the bleeding caused by minor cuts, bruises, and injuries, and allow blood vessels to heal. The process is automatic; the body activates platelets in the blood, they clump together, and they then dissolve after healing has occurred.

In some people, however, blood cells have a greater tendency to stick together and form problematic blood clots known as VTEs (venous thromboembolisms). There are several types of serious VTEs and other blood clots:

• A DVT (deep vein thrombosis) is a clot that forms in a blood vessel, usually in the legs.
• A pulmonary embolism (PE) is caused by a thrombosis that’s moved through the blood vessels to the lungs, often leading to cardiac arrest or other serious heart or lung issues.
• A cerebral embolism is caused by a thrombosis that’s moved to the brain to block blood and oxygen flow, usually causing stroke.
• A coronary thrombosis is a clot that has formed in the heart’s arteries, often leading to heart attack.

These clots are serious medical issues and require medical attention. Clots that travel from the legs or form elsewhere in the body are likely to be much more dangerous and potentially life-threatening.

Blood clots can be caused by many issues, including heart or peripheral artery disease, surgery or physical trauma, prolonged bed rest, cancer, some types of medications, and immune disorders. Other risk factors include a family history of clots, pregnancy, obesity, and smoking.

Treating Blood Clots

Patients with DVTs and those at risk of developing blood clots are almost always given blood-thinning medications as part of their treatment regime. There are two classes of drugs used: anticoagulants and antiplatelets. In reality, neither actually thins the blood, but both lower the chances that clots will develop. However, they also make patients more likely to bleed.

Those who have had heart surgery, heart attacks, or strokes are usually prescribed antiplatelet drugs that prevent blood platelets from binding together unnaturally. Aspirin is, by far, the most commonly used antiplatelet drug; others include clopidogrel (Plavix) and dipyridamole (Persantine).

Anticoagulants, which slow down the formation of clots by interfering with the body’s normal clotting process, are prescribed more often. They’re taken by many patients with heart disease or congenital heart defects, abnormal heart rhythms like atrial fibrillation (AFib), blood vessel diseases, and those who’ve undergone heart valve replacement.

Anticoagulants are also commonly prescribed after many surgeries when patients must remain stationary, for those who have a history of clots or clotting disorders, and some types of cancer. Some patients only take these blood thinners while they remain at risk for developing clots, while many others likely to experience blood clots are put on a lifetime regime of anticoagulants.

Some of the blood thinners prescribed as anticoagulants are old-school meds like warfarin and heparin, but newer drugs like Eliquis and Xarelto have become first-line alternatives because they’re easier to administer and have lower chances of causing uncontrolled bleeding.

Most anticoagulants are taken orally, although some can be administered with injections or infusions. No matter how they’re taken, though, they end up in the same place that CBD does: in the liver for metabolisation.

CBD, Blood Thinners, and the Liver

As we’ve mentioned, blood thinners and CBD are each broken down in the liver before being released into the bloodstream to do their work. Many medications and substances, including CBD and some anticoagulants, are metabolised by the same liver enzymes in the so-called CYP family.

That can cause a problem if cannabidiol and one of those blood thinners are taken at the same time. The enzymes may be overloaded with work and some of the anticoagulant may not be broken down efficiently, meaning some of the drug could remain in the body longer than expected — and cause an increased risk of substantial bleeding.

There’s a second, even bigger issue involving liver enzymes. CBD is also believed to inhibit the activity of CYP enzymes, slowing or even blocking the enzymes’ activity. That would result in even higher levels of some blood-thinning medications remaining in the system and an even higher bleeding risk.

Both of those problems make it potentially dangerous for some patients to use both cannabidiol and one of the anticoagulants metabolised by the CYP enzymes.

There are two more potential concerns to be aware of.

Some research implies that CBD may widen blood vessels, helping to lower blood pressure but also letting blood flow more quickly. Other research suggests that cannabidiol may slow the body’s production of a protein (thromboxane A2) important for blood clotting; that would make blood flow more freely as well. Both issues could increase the risk of heavy bleeding.

The latter two issues aren’t as concerning as the liver enzyme conflicts we’ve discussed, since they’re more theoretical than proven medical issues. But all of this information leads to one important recommendation.

Anyone taking blood thinners should definitely discuss the use of cannabidiol with their doctor before giving any CBD product a try. In the best case, it’s a precaution worth taking; in the worst case, it could be a life-saving conversation.

Which interactions raise a red flag? Let’s close with that important information.

CBD and Blood Thinners: Problematic Interactions

People taking antiplatelet medications like aspirin, clopidogrel (brand name: Plavix), or dipyridamole (Persantine) are at the least risk of a clash between their blood thinner and CBD. Some issues are still possible, but they’re considered the least likely to occur.

A few blood thinning medications aren’t metabolised by the CYP enzymes, so there’s much less of a chance that patients will be negatively affected to any large extent if they add CBD to their regime. The med that’s been a go-to anticoagulant for decades, heparin, is among them, as are edoxaban (brand name: Lixinia) and dabigatran (Pradaxa).

The biggest risk of uncontrollable bleeding comes when taking newer blood thinners like apixaban (brand name: Eliquis), rivaroxaban (Xarelto), and another old standby, warfarin (Coumadin or Jantoven). Patients taking those medications should avoid using CBD products until they’ve cleared the concurrent use of cannabidiol and anticoagulants with their doctor.

For those thinking of using CBD products while on the blood thinners mentioned in the first two paragraphs above, it’s still best to seek medical advice beforehand. Many potential interactions can be avoided by switching to a different prescription medication, or lessened by changing doses.

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