Fondaparinux Is an Injectable Anticoagulant Used to Prevent and Treat Blood Clots

Fondaparinux (brand name Arixtra) is a prescription injectable blood thinner that helps prevent dangerous blood clots from forming in your veins. It's commonly used after surgery and for treating deep vein thrombosis (DVT) and pulmonary embolism (PE).

If your doctor has prescribed Fondaparinux — or you're researching it because a loved one is taking it — this guide covers everything you need to know: what it is, how it's used, proper dosing, who shouldn't take it, and how much it costs in 2026.

What Is Fondaparinux?

Here are the key facts about this medication:

• Generic name: Fondaparinux Sodium
• Brand name: Arixtra
• Drug class: Synthetic selective Factor Xa inhibitor (anticoagulant)
• Manufacturer: Viatris (brand Arixtra); generic versions by Dr. Reddy's Laboratories, Apotex, and others
• FDA approved: Yes — for DVT prophylaxis and DVT/PE treatment
• Controlled substance: No — Fondaparinux is not a controlled substance
• Generic available: Yes

Unlike older blood thinners such as Heparin, Fondaparinux is a fully synthetic medication. It doesn't come from animal sources, which makes it an important option for patients who cannot use heparin-based products — particularly those with heparin-induced thrombocytopenia (HIT).

What Is Fondaparinux Used For?

Fondaparinux is FDA-approved for several uses:

Preventing Blood Clots After Surgery (DVT Prophylaxis)

• Hip fracture surgery (including extended prophylaxis up to 32 days)
• Hip replacement surgery
• Knee replacement surgery
• Abdominal surgery in patients at risk for blood clots

Treating Blood Clots

• Acute deep vein thrombosis (DVT) — used in combination with Warfarin
• Acute pulmonary embolism (PE) — used in combination with Warfarin when initial therapy is administered in the hospital
• Venous thromboembolism (VTE) in pediatric patients aged 1 year or older weighing at least 10 kg

Off-Label Uses

Doctors sometimes prescribe Fondaparinux for conditions beyond its FDA-approved indications:

• Heparin-induced thrombocytopenia (HIT) — as an alternative anticoagulant
• Acute coronary syndromes (unstable angina, non-ST-elevation heart attack)
• Adjunctive therapy in certain types of heart attacks
• Superficial vein thrombosis

How Is Fondaparinux Taken?

Fondaparinux is given as a subcutaneous injection — a shot under the skin, typically in the abdominal area. It is not taken by mouth and cannot be given intravenously for most indications.

Available Strengths

Fondaparinux comes in single-use prefilled syringes in four strengths:

• 2.5 mg/0.5 mL
• 5 mg/0.4 mL
• 7.5 mg/0.6 mL
• 10 mg/0.8 mL

Typical Dosing

For DVT prophylaxis (preventing clots after surgery):

• 2.5 mg injected once daily
• First dose given 6–8 hours after surgery, once bleeding has stopped
• Usually continued for 5–9 days
• For hip fracture surgery, may be extended up to 32 days

For DVT/PE treatment (treating existing clots):

• Under 50 kg: 5 mg once daily
• 50–100 kg: 7.5 mg once daily
• Over 100 kg: 10 mg once daily
• Used together with Warfarin for at least 5 days until INR reaches 2–3

Self-Injection at Home

Many patients learn to inject Fondaparinux at home. Your doctor or nurse will teach you the proper technique. Key points:

• Inject into the fatty tissue of the abdomen
• Rotate injection sites to avoid irritation
• Each syringe is for single use only — do not reuse
• Do not mix with other medications
• Store at room temperature (59°F–86°F); do not freeze

Who Should Not Take Fondaparinux?

Fondaparinux is not safe for everyone. It is contraindicated in the following situations:

• Severe kidney impairment — creatinine clearance below 30 mL/min (the drug is cleared by the kidneys)
• Body weight under 50 kg — for prophylaxis indications only, due to increased bleeding risk
• Active major bleeding — if you're currently experiencing significant bleeding
• Bacterial endocarditis — an infection of the heart valves
• Thrombocytopenia with positive anti-platelet antibody test in the presence of Fondaparinux
• Known allergy to Fondaparinux Sodium

Additionally, Fondaparinux carries an FDA black box warning about the risk of spinal/epidural hematoma in patients receiving spinal anesthesia or spinal puncture. This is a rare but potentially devastating complication that can cause permanent paralysis. Learn more about this and other risks in our Fondaparinux side effects guide.

Special populations:

• Elderly patients — use with caution; higher bleeding risk
• Pregnancy — Category B; use only if clearly needed
• Breastfeeding — unknown if excreted in breast milk; discuss with your doctor
• Children — approved for VTE treatment in children ≥1 year old weighing ≥10 kg

How Much Does Fondaparinux Cost?

The cost of Fondaparinux varies widely depending on whether you're buying the brand or generic and whether you have insurance:

• Brand (Arixtra) retail price: $300–$2,500 for a course of treatment (10 prefilled syringes), depending on strength
• Generic with discount card: As low as $83–$315 for 10 prefilled syringes (2.5 mg strength)
• Generic retail (no discounts): Around $2,497

Insurance coverage: Most insurance plans cover generic Fondaparinux, though some may require prior authorization or classify it as a specialty medication. Some plans use step therapy, requiring you to try Enoxaparin (Lovenox) first.

If cost is a barrier, explore our detailed guide on how to save money on Fondaparinux, including discount cards, patient assistance programs, and other options.

Final Thoughts

Fondaparinux is a trusted, FDA-approved anticoagulant that plays a critical role in preventing and treating blood clots. Whether you're recovering from surgery or managing DVT/PE, understanding how this medication works, how to take it properly, and what to watch for can help you use it safely and effectively.

If you're having trouble finding Fondaparinux at your pharmacy, use Medfinder to locate it in stock near you. And for more on how it works at the molecular level, see our guide on Fondaparinux's mechanism of action.