Dalteparin and Fondaparinux Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fondaparinux Injection
Dalteparin
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased risk of bleeding
Interaction Deep Dive
The concomitant use of fondaparinux with other anticoagulants, such as dalteparin, may increase the risk of major bleeding events due to additive anticoagulation. Coadministration of dalteparin with fondaparinux may also increase the risk of developing epidural or spinal hematomas in patients who are receiving neuraxial anesthesia or undergoing spinal puncture. If coadministration is required, close monitoring for signs and symptoms of bleeding, and neurological impairment in patients who are receiving neuraxial anesthesia or undergoing spinal puncture1.
Why it happens (mechanism)
Additive anticoagulation
Common questions
Can I take Dalteparin and Fondaparinux Injection together?
Increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Dalteparin and Fondaparinux Injection interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Dalteparin or Fondaparinux Injection need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: ARIXTRA(R) subcutaneous injection, fondaparinux sodium subcutaneous injection. GlaxoSmithKline, Research Triangle Park, NC, 2010. DailyMed
Keep reading about Fondaparinux Injection
Keep reading about Dalteparin
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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