Fluindione and Dexamethasone Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Dexamethasone Injection
Fluindione
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 or diminished effects of fluindione
Interaction Deep Dive
Caution should be used when dexamethasone and fluindione are used concomitantly because of an increased risk for bleeding. Studies in adults and children have shown that corticosteroids can potentiate the effects of anticoagulants and increase the INR level leading to an increased risk of bleeding. In patients receiving fluindione therapy, the prothrombin time (PT) or INR should be closely monitored with the addition and withdrawal of treatment with corticosteroids, and should be reassessed periodically during concurrent therapy. Adjustments of the fluindione dose may be necessary in order to maintain the desired level of anticoagulation. A 50% reduction of the oral anticoagulant dose during 4 days of high dose oral dexamethasone therapy was generally sufficient to keep the INR in the target range in one prospective study2.
Why it happens (mechanism)
Unknown
Literature reports
1 report — tap to read
a) In a prospective study of patients with multiple myeloma (n=6) or AL amyloidosis (n=3), taking fluindione (n=8) or warfarin (n=1), high dose concurrent oral dexamethasone (DXM) therapy increased the INR significantly. Patients were studied for a total of 10 cycles and received oral dexamethasone 40 mg/day for 4 days every 28 days alone (n=4) or with melphalan (n=5). Two control groups were used, with the first control group consisting of patients (n=5) on DXM 40 mg/day who did not receive oral anticoagulants, and the second control group consisting of patients (n=4) treated with oral anticoagulants, but who were not receiving corticosteroids and 2 patients who were receiving neither. Mean INR at baseline was 2.75 (range, 1.8 to 3.6) compared to a mean INR after DXM of 5.22 (range, 3.09 to 7.07) and reached a maximum after a mean of 4.3 days (range, 3 to 6 days). This increase was significant in the 8 patients receiving fluindione (p=0.01). Oral anticoagulants were temporarily stopped in 8 of the 10 cycles (range, 1 to 4 days), with vitamin K required in 2 cycles. A dose reduction of 50% for the oral anticoagulant during the 4 days of DXM therapy was generally sufficient to keep the INR in the target range. Plasma concentrations of the anticoagulants were elevated after DXM administration before the INR increased. and DXM alone did not increase the prothrombin time as seen in the controls. Two cases of minor oral bleeding were observed that resolved after transient withdrawal of oral anticoagulants 2.
Common questions
Can I take Fluindione and Dexamethasone Injection together?
Increased risk of bleeding or diminished effects of fluindione Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fluindione and Dexamethasone Injection interaction?
It is rated moderate. Can be significant — usually manageable with 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Fluindione or Dexamethasone 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 anything you'd monitor while I'm on both?
References (2)
- Product Information: dexamethasone tablets, oral solution, oral solution concentrate, dexamethasone tablets, oral solution, oral solution concentrate. Roxane Laboratories,Inc, Columbus, OH, 2005. DailyMed
- Sellam J, Costedoat-Chalumeau N, Amoura Z, et al: Potentiation of fluindione or warfarin by dexamethasone in multiple myeloma and AL amyloidosis. Joint Bone Spine 2007; 74(5):446-452. PubMed
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