Interactions of Cannabis (CBD/THC) and Medications
How do medicines and cannabis interact?
Cannabis use has been partially legalized in Germany. Even before legalization, marijuana and hashish were widely used in the population. For that reason, we want to point out possible interactions.
Interaction between cannabis (CBD/THC) and medications: CBD and THC are the two best-known active ingredients among more than one hundred
cannabinoids in the hemp plant
Already known, for example, is an interaction with the "blood thinner" Marcumar and its generics - that is, drugs with the same active ingredient but a different brand name. Using cannabis while on Marcumar therapy can increase the risk of bleeding. This can be dangerous because, as Marcumar patients know, bleeding while taking Marcumar can be hard to stop. This applies not only to external bleeding but also, for example, to bleeding in the gastrointestinal tract. A similar interaction with cannabis is possible for another group of blood-thinning drugs, the direct oral anticoagulants (DOACs) such as Pradaxa (Dabigatran), Xarelto (Rivaroxaban) and Eliquis (Apixaban).
The opposite can happen when anticoagulation is achieved with Plavix (Clopidogrel). Here, cannabis can reduce the antithrombotic (blood-thinning) effect. In that case, the risk that blood clots will form is increased by using cannabis.
Similar interactions have been described for many other medications, while some are still only suspected. We used the example of blood thinners because this interaction is considered proven and blood thinners are commonly prescribed for cardiovascular diseases – for example after previous heart attacks and strokes.
So that your high doesn't turn into a problem, please don't hesitate to ask your pharmacist about possible interactions with your medications if you plan to use cannabis.
Sources:
This article is from Tensana – the leading app since 2011, helping hundreds of thousands of people monitor their blood pressure every day.
Our content is based on carefully researched, evidence-based data and is continuously updated (as of 12/2025).
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.
We hope you found the article helpful. For good blood pressure control, it's important to take your medications correctly. Our app Tensana will gladly remind you when to take them.
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