I am subject to the Common Law Act (and a few other professional restrictions) which allows me to practice. I am prevented from providing advice or perceived prescribing of supplements unless I have conducted a face to face consultation. Failure to do so would result in me being de registered. However, I am able to provide general information. Homeopathic doses of arnica are usually extremely diluted and depending on the brand and strength of the piliules. It is quite possible that there is very little of the actual Arnica Montana plant in the preparation, it really depends on the concentration, this is the same for homeopathic preparations in general. I am not a fan of ingesting Arnica whilst on blood thinning meds. There have been a few reports indicating that arnica can cause internal bleeding, possibly due to arnica’s ability to enlarge the capillaries to improve blood flow. I have read reports that it can interact with blood thinners (e.g., warfarin, heparins including dalteparin, enoxaparin,) antiplatelet drugs (e.g. clopidogrel, ticlopidine), and other anticoagulants such as Lovenox which quite a few members are prescribed post surgery. Additionally, it has been reported that it may irritate mucous membranes, cause stomach pain, diarrhea, and vomiting, dizziness, tremors, and heart irregularities. I would defintely suggest letting your surgeon and treating physician know if you decide to take Homeopathic Arnica Pilules or any other homeopathic preparations orally. Cheers.