Borage and Fondaparinux: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fondaparinux
Borage
No brand names on record
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
Theoretically, borage oil may increase the risk of bleeding if taken with anticoagulants. Borage oil contains between 20% and 26% gamma-linolenic acid4, one of the main components of evening primrose oil thought to be responsible for its anticoagulant effects. Evening primrose oil inhibited platelet aggregation and prolonged bleeding time in humans 5. Gamma-linolenic acid from evening primrose oil inhibited thromboxane B2 production and increased prostacyclin production 5. Caution is advised if borage oil is taken with anticoagulants 21.
Why it happens (mechanism)
Additive antiplatelet effects
Literature reports
1 report — tap to read
a) Evening primrose oil (EPO) significantly reduced platelet aggregation and prolonged bleeding time in a randomized, blinded, crossover study of 12 males. Patients received EPO 3 grams daily (providing 2200 milligrams (mg) linoleic acid and 240 mg gamma-linolenic acid) for 4 months. Antiplatelet drugs were discontinued at least 8 weeks before the study. Adenosine diphosphate, adrenaline, and collagen-induced platelet aggregation were significantly reduced compared to placebo after 2 and 4 months of EPO supplementation. Platelet production of thromboxane B2 was significantly decreased from baseline (p less than 0.001) at 3 and 4 months of EPO treatment. Bleeding time increased 40% over baseline after 3 and 4 months of EPO treatment (p less than 0.001) 3.
Common questions
Can I take Borage and Fondaparinux together?
Increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Borage and Fondaparinux interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
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 Borage or Fondaparinux 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 anything you'd monitor while I'm on both?
References (5)
- Heck AM, DeWitt BA, & Lukes AL: Potential interactions between alternative therapies and warfarin. Am J Health Syst Pharm 2000; 57(13):1221-1227. DOI
- Norred CL & Brinker F: Potential coagulation effects of preoperative complementary and alternative medicines. Alt Ther 2001; 7(6):58-67.
- Guivernau M, Meza M, Barja P, et al: Clinical and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production. Prostaglandin Leukot Essent Fatty Acids 1994; 51:311-316. PubMed
- Kowalak JF & Mills EJKowalak JF & Mills EJ (Eds): Professional Guide to Complementary & Alternative Therapies, Springhouse Corp. Bethlehem Pike, PA, 2001.
- Guivernau M, Meza M, Barja P, et al: Clinicial and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production. Prostaglandin Leukot Essent Fatty Acids 1994; 51:311-316.
Keep reading about Fondaparinux
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