Blood Thinning Medications After Joint Replacement

Anticoagulants help prevent blood clots

Patient recieving shot from nurse
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Joint replacement surgery is an effective treatment for severe arthritis. Most patients have a normal recovery following a joint replacement, but there are potential complications. One complication is the risk of developing blood clots after surgery. In order to prevent blood clots after hip replacement and knee replacement, a blood thinning medication, also called an anticoagulant, is given.

How long do anticoagulants need to be taken to prevent a blood clot?

Anticoagulant Medications or Blood Thinners After Surgery

Answer: The optimal length of time to take blood thinning medications has not been precisely established, but there are guidelines that can be followed. The length of time patients take an anticoagulation medication depends on the type of surgery, and the type of anticoagulation medication being used.

The two most commonly used options for blood thinning medications are an injection or a tablet. The injection is usually heparin (e.g. Lovenox), and the tablet is warfarin (Coumadin).

  • Injections
    Injections are often used because the level of blood thinning does not need to be checked with a daily blood test. The medication is given like an insulin shot, usually once a day. It is simple to do, but does require the patient to administer the shot once they have left the hospital.
  • Coumadin
    Coumadin tablets are taken each evening. This medication gradually thins the blood, but it has different effects on different people. Therefore, blood tests must be done to ensure enough Coumadin is given, and that the blood is not too thin. The advantage of Coumadin is that it is a simple way to thin blood, and more practical when needed for a longer time.

    Hip Replacement Surgery

    Following hip replacement surgery, anticoagulation medication should be given for at least 10 to 14 days. The risk of a blood clot can be reduced by continuing blood thinning medications for up to one month, according to some research.

    Knee Replacement Surgery

    After knee replacement surgery, blood thinning medications should be given for at least 10 days. In contrast to hip replacement surgery, there has been no advantage in continuing these medications for a month.

    Limiting the Time on Blood Thinning Medications

    Extending blood thinning medications longer than needed can open up the door for possible complications of having blood that is too thin. These side-effects of anticoagulation medications include bleeding around the incision, or internal bleeding, such as a stomach ulcer or stroke. Risks of bleeding are small, but need to be balanced against the possibility of developing a blood clot.

    If the Doctor Suggests a Different Length of Time for Medication

    These are guidelines that have been established and agreed upon by the American College of Chest Physicians and the American Academy of Orthopaedic Surgeons. That said, there are many individual factors that may lead to a change in duration of these medications.

    For example, patients with pre-existing medical conditions, patients who develop a blood clot, or other high-risk patients may need to continue these medications for longer than the aforementioned guidelines.

    You should follow your doctor's recommendations for the length of time to continue blood thinning medications. If you have any questions about how long to continue anticoagulation medication, you should contact your doctor.


    Friedman, RJ "Optimal Duration of Prophylaxis for Venous Thromboembolism Following Total Hip Arthroplasty and Total Knee Arthroplasty" J Am Acad Orthop Surg 2007 15: 148-155.