Day: October 2, 2023

Last updated: September 2026. The short answer In healthy people taking normal amounts, there is no good evidence that CBD oil causes bleeding or stops blood from clotting properly. The real concern is medication: CBD can change how the body breaks down some blood thinners, especially warfarin, which can make them stronger than intended. If you take any blood-thinning medicine, speak to your doctor or pharmacist before taking CBD, and don’t start or stop CBD without telling them. How blood clotting works (in brief) When you cut yourself, small blood cells called platelets clump together at the injury, and proteins in the blood called clotting factors form a mesh that seals the wound. People at risk of dangerous clots, for example after a stroke, with atrial fibrillation or after a deep vein thrombosis, are often prescribed medicines that slow this process down. The balance matters: too little clotting means bleeding, too much means clots. Does CBD oil thin the blood? CBD is not a blood thinner, and it is not sold or used as one. Some lab and animal studies have looked at whether cannabinoids affect how platelets clump together, with mixed results. There is no convincing evidence that the amounts of CBD in food supplements, typically 10 to 50mg a day, have a meaningful effect on clotting in healthy people. CBD and blood thinners: the real issue The main risk comes from how the body processes CBD. CBD is broken down in the liver by a family of enzymes called CYP450. Many medicines, including several blood thinners, are processed by the same enzymes. CBD can slow some of these enzymes down, which can mean more of the medicine stays in your blood for longer. Warfarin Warfarin is the best-documented example. Doctors have reported cases where patients on warfarin started CBD and their INR (the blood test that measures how long blood takes to clot) went up, meaning their blood was clotting more slowly than intended. In one published case, a patient’s warfarin dose had to be lowered by about 30% after starting a prescription CBD medicine (Grayson et al., 2018). Those cases involved high medical doses of CBD, but it is the reason warfarin users need to be careful. Newer blood thinners (DOACs) Medicines such as apixaban (Eliquis) and rivaroxaban (Xarelto) are also partly processed by CYP450 enzymes. There is much less data on CBD with these medicines, so the cautious approach is to treat them the same way: check with your doctor or pharmacist first. Antiplatelet medicines Clopidogrel (Plavix) needs to be activated by a liver enzyme that CBD can also affect, so in theory CBD could change how well it works. Low-dose aspirin is processed differently, but anything that affects bleeding is worth mentioning to your GP. If you take a blood thinner and want to try CBD Other supplements that can affect bleeding CBD is not the only supplement to think about. Fish oil, high-dose vitamin E, ginkgo, garlic supplements and turmeric can all affect bleeding, especially alongside blood thinners. If you take several supplements, tell your doctor about all of them. Our guide to CBD and turmeric covers that combination in more detail. CBD before surgery or dental work As a precaution, stop taking CBD and other supplements that may affect bleeding at least two weeks before planned surgery, and tell your surgeon or dentist what you take. What to bring when you talk to your GP or pharmacist A five-minute conversation is all it usually takes. To make it quick and useful, bring: Ask whether CBD is suitable alongside your medicines, and whether you need any extra blood tests if you go ahead. Your pharmacist can check interactions on the spot, and they are often the easiest person to ask. Signs of bleeding to watch for Anyone taking a blood thinner should know the signs of bleeding, whether or not they use CBD. Contact your GP or pharmacist promptly if you notice: If you have severe bleeding, a serious fall or a head injury while taking a blood thinner, seek emergency help straight away. CBD creams and blood thinners CBD creams and balms work on the skin where you apply them, and only a small amount of CBD is thought to reach the bloodstream. That makes an interaction much less likely than with oils, gummies or capsules. Even so, if you take a blood thinner, mention any CBD product to your pharmacist, including creams. Our CBD creams list the CBD content on every product. Food and drink that can affect warfarin If you take warfarin, CBD is only one of several things that can change your INR. Your clinic will usually also mention: The common thread is consistency. Sudden changes, such as starting a new supplement or changing your diet, are what make INR harder to control, so tell your clinic about any change. Frequently asked questions Does CBD oil affect blood clotting? In healthy people taking normal supplement amounts, there is no good evidence that it does. The concern is with blood-thinning medicines, especially warfarin, where CBD can raise the level of the medicine in your blood. Can I take CBD with warfarin? Only with your doctor’s agreement. CBD can raise INR in people taking warfarin. If your doctor is happy for you to try it, they may check your INR more often at first. Can I take CBD with apixaban or rivaroxaban? There is little research, and an interaction is possible because these medicines share liver enzymes with CBD. Check with your doctor or pharmacist first. Does CBD raise or lower blood pressure? Some small studies found a single dose of CBD slightly lowered blood pressure, especially under stress. If you take blood pressure medication or have low blood pressure, speak to your doctor first. Is CBD safe for people with heart conditions? Many people with heart conditions take several medicines, so the interaction risk is higher. Always ask your cardiologist, GP or pharmacist before starting CBD. Can I take CBD