Bone Fractures and Warfarin

Publication Date: 
Fri, 05/01/2015
By: Alere Staff

Fractures are a worrisome injury for anyone, much less a patient on a blood thinner like warfarin. A fracture, or broken bone, is an injury that will almost always require medical attention. If the fracture is an injury received from a major trauma, like a car accident or a fall, calling 911 may be a necessity.1


A broken bone can be both a painful and frightening experience. Whether you are walking in the kitchen, jogging on the sidewalk or playing recreational sports, fractures can occur. Since no one is immune to breaking a bone, here are some symptoms of a bone fracture:2

  • An out-of-place or misshapen limb or joint.
  • Swelling, bruising and bleeding.
  • Intense pain.
  • Numbness and tingling.
  • Limited mobility or inability to move a limb.

While most broken bones are fractures, not all fractures are the same. If the broken bone pierces through the skin, it is considered an open or compound fracture. Meanwhile, overusing your muscles and limbs can cause stress fractures, also known as hairline fractures, which are small cracks that occur within the bone that can be no bigger than a human hair.

Underlying Causes

Stress or impact with an object may be the direct reason for a bone to break, but there are other causes that we may not think about on a day-to-day basis. An underlying cause of fractures is weakened bone from osteoporosis or low bone density.2 Loss of bone density within our bodies is an aspect of aging. As a patient taking warfarin for possible long-term use, you may wonder if the drug contributes to an increase in bone density loss, resulting in a higher likelihood of these bone fractures. Vitamin K does play an important role in healthy bone development and maintenance. Therefore a diet that’s very low in vitamin K would potentially cause problems for a patient consuming too little of this important vitamin.

Bone health is measured by bone mineral density and bone mass. Patients with bone fractures had 70% lower vitamin K in their bloodstream.3 It is fair to reason that deliberately reducing or eliminating foods high in vitamin K in your diet would reduce your vitamin K reserves to support healthy bone development. You would therefore have an increased risk of a bone weakness.

Bones, Vitamin K and Warfarin

Science has proven that vitamin K plays an important role in healthy bone development. We also know that patients taking warfarin have, historically, been instructed to reduce or eliminate foods containing vitamin K such as leafy green vegetables from their diet. The result is lower levels of vitamin K in the body which may lead to less than healthy bone development.

Does warfarin by itself weaken your bone health? Warfarin works by blocking the formation of vitamin K dependent factors in the blood to help your body’s ability to repair injuries to your blood vessels inside your body and out.4 A 2015 study evaluated patients taking warfarin for five years or longer and did not see any risk of developing bone health issues in key areas (hip, neck, spine) of the body.5

Another aspect to consider is, as we age, our bodies become less efficient at absorbing calcium and using it efficiently to support proper bone health. With or without taking warfarin, as we age our bones lose mass and become less dense.

The fore mentioned study of 9,423 patients helps to dispel the myth that warfarin is directly responsible for weaker bones in patients taking warfarin for five years or longer. The results are preliminary and the study is pending publishing.

Care of Fractures

The best thing to do when you get a bone fracture is to seek immediate medical attention. Once that is done, these steps will need to be considered:1

  • Stop any bleeding using a sterile bandage, clean cloth or a clean piece of clothing.
  • Try to not move the injured area and attempt to keep it still.
  • Apply ice packs to keep swelling down and relieve pain.
  • Treat for any possible signs of shock.

Treatment of fractures will usually include a cast or splint, but serious broken bones may require surgery to put in plates, pins or screws to keep a bone in place.2 Treatment can also include pain medications that can affect your INR. Make sure you speak with your doctor before starting any form of treatment.

Interested in learning more about bone health and warfarin? Check out these similar articles:


  1. Mayo Clinic Staff. Fractures (Broken Bones): First Aid. Mayo Clinic. March 19, 2015. Retrieved from website:
  2. U.S. National Library of Medicine. Fractures. Medline Plus. March 11, 2015. Retrieved from webstie:
  3. Vermeer, C. Dec. 2003. Vitamin K Supplementation: A Simple Way to Improve Bone and Vascular Health. Agro-food Industry Hi-tech. 17-20.
  4. Fiumara, K. et al. A Patient’s Guide to Taking Coumadin/Warfarin. Circulation. 2009;119;e220-e222. Retrieved from website:
  5. Vaninetti N, et al. Warfarin Use and Baseline Bone Mineral Density in the Population-Based Canadian Multicentre Osteoporosis Study.ENDO 2015; Abstract SAT-236.