Fondaparinux is an anticoagulant (blood thinner) that prevents the formation of blood clots.

Fondaparinux is used to prevent a type of blood clot called deep vein thrombosis (DVT), which can lead to blood clots in the lungs (pulmonary embolism). A DVT can occur after certain types of surgery.

Fondaparinux is also used together with warfarin (Coumadin) to treat DVT, including pulmonary embolism.

Fondaparinux may also be used for other purposes not listed in this medication guide.

You should not use this medication if you are allergic to fondaparinux, heparin, or pork products, or if you have active bleeding, severe kidney disease, an infection in the lining of your heart, or a low level of platelets in your blood after testing positive for a certain antibody while using fondaparinux.

You should not use fondaparinux to prevent blood clots after surgery if you weigh less than 110 pounds (50 kilograms).

Fondaparinux may cause you to bleed more easily, especially if you have: a bleeding disorder, hemorrhagic stroke, eye problems caused by diabetes, uncontrolled high blood pressure, stomach or intestinal bleeding or ulcer, recent brain or spine surgery, recent eye surgery, or if you are an older adult who has kidney problems.

Fondaparinux can cause a very serious blood clot around your brain or spinal cord if you undergo a spinal tap or receive spinal anesthesia (epidural), especially if you have a genetic spinal defect, a history of spinal surgery or repeated spinal taps, or if you are using other medications to treat or prevent blood clots. Symptoms of this type of blood clot include numbness, tingling, muscle weakness, or loss of movement. Tell any doctor who treats you that you are using fondaparinux.

Many other drugs (including some over-the-counter medicines) can increase your risk of bleeding or life-threatening blood clots, and it is very important to tell your doctor about all medicines you have recently used.

Blood clots around the brain or spinal cord may occur if you use fondaparinux with other drugs that can affect blood clotting, including aspirin, non-steroidal anti-inflammatory drugs (NSAIDs) such as Advil or Motrin, and any other medications to treat or prevent blood clots.

Tell your caregivers at once if you have signs of bleeding such as black or bloody stools, coughing up blood, confusion, feeling like you might pass out, or any bleeding that will not stop.

You should not use this medication if you are allergic to fondaparinux, heparin, or pork products, or if you have:

• active or uncontrolled bleeding;

• severe kidney disease;

• an infection in the lining of your heart (also called bacterial endocarditis); or

• a low level of platelets in your blood after testing positive for a certain antibody while using fondaparinux.

You should not use fondaparinux to prevent blood clots after surgery if you weigh less than 110 pounds (50 kilograms).

Fondaparinux may cause you to bleed more easily, especially if you have:

• a bleeding disorder that is inherited or caused by disease;

• hemorrhagic stroke;

• eye problems caused by diabetes;

• uncontrolled high blood pressure;

• stomach or intestinal bleeding or ulcer;

• recent brain, spine, or eye surgery; or

• kidney disease (especially if you are an older adult).

Fondaparinux can cause a very serious blood clot around your brain or spinal cord if you undergo a spinal tap or receive spinal anesthesia (epidural). This type of blood clot could cause long-term paralysis, and may be more likely to occur if you have:

• a genetic spinal defect;

• a history of spinal surgery or repeated spinal taps; or

• if you are using other medications to treat or prevent blood clots.

FDA pregnancy category B. Fondaparinux is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

It is not known whether fondaparinux passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.