CBD oil and Sintrom: does CBD affect blood clotting?
CBD oil has taken the wellness world by storm, but is it suitable for everyone? Does it have any contraindications? These are some of the questions users may have. Today we look at whether CBD combines well with anticoagulant medicines, in particular Sintrom (acenocoumarol) and warfarin. Can CBD affect blood clotting and the effect of these medicines? We answer these questions based on what is known from current scientific research.
Note: this is an informational article and is not intended to prevent, diagnose or treat any disease. Its content may complement, but never replace, the diagnosis or treatment of any disease or symptom. Cannactiva products are not medicines and are intended for external use. Consult your doctor before using CBD.
Can CBD affect blood clotting?
Yes, cannabidiol or CBD can influence blood clotting. According to preclinical studies, cannabidiol affects platelet aggregation. Although its effects have not been shown to be contraindicated when it is used on its own or by healthy people, caution should be taken when taking CBD orally in the case of illness, or if other medicines are being taken.
CBD oil and anticoagulant medicines
What are anticoagulants?
Anticoagulants are medicines that “thin” the blood; that is, they prevent the blood from clotting too quickly, ensuring a smooth flow through our veins and arteries.
They are given to prevent blood clots (thrombi) and serious complications such as heart attacks or strokes. However, their action requires careful monitoring to avoid bleeding.
How do anticoagulants work and how are they metabolised?
Anticoagulants are metabolised in the liver and act by targeting specific blood proteins involved in the clotting process.
Sintrom, whose active ingredient is acenocoumarol, is a widely used anticoagulant today that acts as a vitamin K antagonist. Vitamin K is a key element in the coagulation cascade.
Like Sintrom, warfarin is also an anticoagulant that interferes with vitamin K.
There are other anticoagulants on the market that do not depend on this vitamin, including heparin, enoxaparin (Lovenox), dabigatran (Pradaxa) and rivaroxaban (Xarelto).
CBD and its influence on the effect of anticoagulant medicines
CBD is metabolised in the liver and may influence the function of certain liver enzymes. This is crucial because these same enzymes also metabolise many other drugs, including anticoagulants.
When CBD inhibits these liver enzymes, it can raise the levels of other medicines in the bloodstream. This is a concern with medicines that have a narrow therapeutic index, where too much or too little can be problematic.
Anticoagulant medicines and CBD oil: possible interactions
Possible effects of CBD on blood clotting
Coagulation is the process by which blood forms clots to stop bleeding. It involves a series of chemical reactions that lead to the formation of a solid mass (a clot) from liquid blood. This process involves vitamin K and takes place through platelet aggregation, the formation of fibrin strands with the help of thrombin, and the activation of other proteins in the blood. Coagulation is crucial for wound healing and for preventing excessive bleeding.
Preclinical studies have shown that cannabinoids can influence coagulation. CBD does not affect thrombin activity as much as cannabinol (CBN) and tetrahydrocannabinol (THC) do. However, CBD can disrupt platelet aggregation (1).
Scientific studies in humans on CBD and blood clotting
Scientific studies have looked at the effects of CBD on coagulation in preclinical models. In these, CBD has been observed to interfere with platelet aggregation (1).
There are no studies on the antiplatelet effect of CBD in humans, because of the difficulty of staying within an ethical framework when a person’s risk of bleeding is increased.
There are reported clinical cases in which the combined use of CBD and anticoagulants has been monitored. In these cases, a significant decrease in coagulation was observed, so the international normalised ratio (INR) of clotting time should be monitored at the start of treatment and while taking cannabinoids (2).
Other anecdotal reports suggest possible interactions between CBD and anticoagulants. However, most studies focus on the effects on coagulation of THC, the psychoactive compound in cannabis.
Preliminary data suggest that THC could increase the effect of warfarin (it raises the INR), but comprehensive studies in humans are limited (3).
Risks of taking CBD with anticoagulant medication
The main concern with using CBD and anticoagulants at the same time is the risk of excessive anticoagulation. If CBD increases the plasma concentration of the anticoagulant, there may be a higher risk of bleeding episodes.
Recommendations for people taking anticoagulants who want to use CBD
Before combining CBD with anticoagulants, it is essential to consult a healthcare professional. It is crucial to monitor people who are taking cannabis products and anticoagulants at the same time with laboratory tests.
It may be necessary to check anticoagulation levels, by assessing the international normalised ratio (INR), when starting or adjusting CBD. Close monitoring of medication levels and their effects is therefore essential.
Note: this is an informational article and is not intended to prevent, diagnose or treat any disease. Its content may complement, but never replace, the diagnosis or treatment of any disease or symptom. Cannactiva products are not medicines and are intended for external use. Consult your doctor before using CBD.
Frequently asked questions
How does CBD affect anticoagulants?
CBD has the potential to increase blood levels of certain medicines, such as anticoagulants, by inhibiting the liver enzymes that metabolise these drugs. This could enhance their effects and increase the risk of bleeding.
Can I take CBD if I am taking Sintrom?
Mixing CBD and anticoagulants could enhance the effect of anticoagulants such as Sintrom, increasing the risk of bleeding. This should therefore be assessed by your doctor. The dose of Sintrom or of CBD may need to be adjusted.
Can I take CBD if I am taking warfarin?
Complications have been observed in some clinical cases with the concomitant use of cannabis products and anticoagulants such as warfarin. If simultaneous use is necessary, it is recommended that it take place under strict medical supervision.
Are there any known contraindications between CBD and anticoagulants?
Yes, there are reported clinical cases in which the concomitant use of CBD and anticoagulants reduces coagulation beyond the therapeutic range. This has also been observed with other cannabinoids, so precautions should be taken in the therapeutic use of medicinal cannabis and anticoagulant medicines.
Is CBD safe to use?
Yes. CBD has a wide range of potential benefits, but it is not without its complexities, especially when combined with certain medicines. We explain this in more detail below.
Sources
- Khayat, W., & Lehmann, C. (2022). The Endocannabinoid System: A Potential Therapeutic Target for Coagulopathies. Metabolites, 12(6), 541. https://doi.org/10.3390/metabo12060541
- Grayson, L., Vines, B., Nichol, K., Szaflarski, J. P., & UAB CBD Program (2017). An interaction between warfarin and cannabidiol, a case report. Epilepsy & behavior case reports, 9, 10–11. https://doi.org/10.1016/j.ebcr.2017.10.001
- Damkier, P., Lassen, D., Christensen, M. M. H., Madsen, K. G., Hellfritzsch, M., & Pottegård, A. (2019). Interaction between warfarin and cannabis. Basic & clinical pharmacology & toxicology, 124(1), 28–31. https://doi.org/10.1111/bcpt.13152
