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Overview: Fondaparinux is a blood thinner that you inject under the skin to treat or prevent blood clots. Some common side effects are bleeding, bruising, dizziness, trouble sleeping, or itchiness and discomfort at the injection site. Seek medical care right away if you have severe bleeding or bleeding that is taking a long time to stop.

Uses

What is fondaparinux used for?

Fondaparinux is commonly used for the following reasons.

  • To prevent blood clots in the leg, also called deep venous thrombosis (DVT), after certain hip, knee, or stomach surgeries
  • To treat blood clots, including a DVT or a blood clot in the lung, also called a pulmonary embolism (PE)

Fondaparinux may also be used for other conditions as determined by your health care provider.

How does fondaparinux work (mechanism of action)?

Fondaparinux is a blood thinner, or anticoagulant. It works by blocking certain substances in the blood that form clots.  

How is fondaparinux supplied (dosage forms)?

Brands and other names

  • Arixtra
  • Fondaparinux 

Dosage forms and strengths

  • 2.5 mg, 5 mg, 7.5 mg, 10 mg solution for injection (single-dose prefilled syringe)

How should I store fondaparinux?

Fondaparinux should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C), for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of fondaparinux?

The most common side effects of fondaparinux are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Anemia
  • Low blood pressure
  • Trouble sleeping, dizziness, and confusion
  • Increased bleeding
  • Bleeding, rash, and itching at the injection site     
  • Wound drainage increased
  • Low potassium level
  • Bruises or discolored spots on the skin

There may be other side effects of fondaparinux that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of fondaparinux?

The most serious side effects of fondaparinux are described below. Tell your health care provider if you have any of these side effects that bother you.

Severe Allergic Reactions. Fondaparinux may cause allergic reactions, which can be serious. Stop using fondaparinux and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Spinal blood clots. Blood clots can form around the spinal cord if you are using fondaparinux and have a spinal tap or receive an epidural. These blood clots can cause long-term or permanent paralysis (unable to move). Your risk is higher if a thin tube (catheter) is placed in your spine, you are taking other medicines that may cause bleeding, including other blood thinners, you have a history of troublesome or repeated spinal punctures, you have problems with your spine, or had a recent surgery on your spine. Your health care provider will monitor you closely during the procedure. Tell your health care provider right away if you have back pain, tingling, numbness, muscle weakness (especially in your legs and feet), or loss of control of the bowels or bladder.  

Severe Bleeding. Fondaparinux can increase your risk of severe bleeding that can lead to death. Some patients with serious bleeding may need a blood transfusion or surgery. Call your health care provider right away if you have any of the following signs of severe bleeding while using fondaparinux.

  • Pink, red, or brown urine (pee)
  • Vomit with blood that looks like coffee grounds
  • Red or black stools (looks like tar)
  • Coughing up blood or blood clots

Severely Low Platelet Levels. Fondaparinux can cause you to have a severely low number of platelets in your blood, also called thrombocytopenia. Platelets help to form blood clots. Having a low level of platelets may increase your risk of bleeding. Tell your health care provider if you have any of the following symptoms of low platelet levels.

  • Easy bruising or bleeding
  • Bleeding that does not stop
  • Nosebleeds

Warnings & Precautions

Who should not use fondaparinux?

Allergies to Ingredients. People who are allergic to any of the following should not use fondaparinux.

  • Arixtra
  • Fondaparinux
  • Latex
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all the ingredients in the specific fondaparinux products they stock.

Kidney Problems. Certain kidney problems can increase your risk of bleeding with fondaparinux. If there is a concern about the health of your kidneys, your health care provider may do tests to see if they are working well enough to use this medicine.

Bleeding problems. Do not use fondaparinux if you have uncontrolled bleeding.  

Heart infection. Do not use fondaparinux if you have a heart infection (bacterial endocarditis).  

Low platelets. Do not use fondaparinux if you have a low platelet count and have tested positive for a certain antibody.

Low body weight (adults). Do not use fondaparinux to prevent a blood clot if you are an adult and weigh less than 110 pounds.

What should I know about fondaparinux before using it?

Do not use fondaparinux unless it has been prescribed to you by a health care provider. Use it as prescribed.

Do not share fondaparinux with other people, even if they have the same condition as you. It may harm them.

Keep fondaparinux out of the reach of children.

After training from a health care provider, fondaparinux may be given at home by you or a caregiver. Fondaparinux is given as an injection under the skin and should not be injected into a muscle. Inject fondaparinux into a skin fold of the lower stomach (abdomen) area, and rotate injection sites, such as between the left and right sides of the abdomen. Read and follow the instructions for the product you have and make sure you understand how to use it properly. If you have any questions, talk to your health care provider.

What should I tell my health care provider before using fondaparinux?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if fondaparinux is right for you.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Bleeding problems, including stomach ulcer
  • Have had problems in the past with pain medication given through the spine
  • Have had surgery to your spine or have a spinal deformity
  • Any recent surgery, including eye surgery
  • History of stroke
  • Kidney or liver problems
  • High blood pressure
  • Diabetic eye disease

Pregnancy. Fondaparinux may cause harm to a fetus. Tell your health care provider if you are or plan to become pregnant. Your health care provider will let you know the best way to treat or prevent blood clots if you are pregnant.

Breastfeeding. It is not known if fondaparinux passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should use fondaparinux while breastfeeding. 

Interactions

Does fondaparinux interact with foods or drinks?

There are no known interactions between fondaparinux and foods or drinks.       

It is unknown if drinking alcohol will affect fondaparinux. The risk of dizziness and confusion may be increased if you drink alcohol while using fondaparinux. Both fondaparinux and alcohol can increase your risk of bleeding, so it is best to limit the amount of alcohol you drink.

Does fondaparinux interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over the counter (OTC) medicines, vitamins/minerals, herbal products, or other supplements you are using.  

In particular, make sure that you discuss if you are using any of the following before using fondaparinux:

  • A blood thinner, which is a medicine used to treat or prevent blood clots, such as warfarin
  • A nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, naproxen, and others, which are found in many prescription and OTC products for pain, swelling, and fever
  • Aspirin

This may not be a complete list of medicines that can interact with fondaparinux. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much fondaparinux?

If you or someone else has used too much fondaparinux, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of fondaparinux?

If you miss a dose, use it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only give the next dose. Do not use double or extra doses.