Warfarin is a medicine that makes your blood less likely to form clots. It is important that you take warfarin exactly as you have been told. Changing how you take your warfarin, taking other medicines, and eating certain foods all can change the way warfarin works in your body. Zocdoc › Answers › What type of bruising do I need to be worried about while on blood thinners? Question I am currently taking Warfarin because i have Blood Clots in my lungs/ Pulminary Embolisms. Warfarin side effects: Watch for interactions. Although commonly used to treat blood clots, warfarin (Coumadin, Jantoven) can have dangerous side effects or interactions that can place you at risk of bleeding. Warfarin can cause severe bruising, especially if the level of the medication becomes too high. Cortisone medications, such as prednisone , promote bruising by increasing the fragility of the tiny blood vessels in the skin. Why the Sudden-Onset Bruising in a Previously Stable Warfarin Patient? Douglas S. Paauw, MD. Disclosures. December 12, 2014. Warfarin Interactions As many clinicians know, TMP/SMX and warfarin. A anticoagulant like warfarin can case unusual bleeding/bruising, but if that happens one needs to discuss the causes with their doctor. If you were in a traffic accident and that caused the bruises it seems wise to me to seek medical evaluation - perhaps the emergency room in a hospital. WARNINGS: Warfarin can cause very serious (possibly fatal) bleeding. This is more likely to occur when you first start taking this medication or if you take too much warfarin. Warfarin is an anticoagulant (blood thinner). Warfarin reduces the formation of blood clots. Warfarin is used to treat or prevent blood clots in veins or arteries, which can reduce the risk of stroke, heart attack, or other serious conditions. Most bruises are caused by physical injury. Some underlying conditions may make bruising more common. Here are 16 possible causes of bruising. Bruising Last revised in March 2016 Next planned review by December 2021. Summary. Back to top Bruising: Summary. A bruise is a haematoma which forms due to bleeding under intact skin into subcutaneous tissue, due to vascular damage or injury.