Warfarin and Glucagon Injection / Solution: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Warfarin
Glucagon Injection / Solution
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
An increased risk of bleeding
Interaction Deep Dive
Treatment with both glucagon and warfarin may increase the anticoagulant effect of warfarin. Monitor patients for unusual bruising or bleeding, as adjustments in warfarin dosage may be required1. Large daily doses of glucagon have been shown to increase the hypoprothrombinemic effect of warfarin, resulting in bleeding episodes 2.
Why it happens (mechanism)
Unknown
Literature reports
1 report — tap to read
a) Twenty-four patients with heart failure who received warfarin and glucagon were retrospectively studied. Thirteen of these patients were administered glucagon in doses of 50 mg or more over two days, and eight of them exhibited excessive inhibition of prothrombin activity. Three patients had evidence of a bleeding episode. However, it must be noted that the majority of these patients were receiving multiple drugs, some of which may have contributed to the alteration of prothrombin time. Smaller doses of glucagon (30 mg) did not appear to interfere with the efficacy of warfarin 2.
Common questions
Can I take Warfarin and Glucagon Injection / Solution together?
An increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.
How serious is the Warfarin and Glucagon Injection / Solution interaction?
It is rated major. Potentially serious — often needs a change or close 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 "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Warfarin or Glucagon Injection / Solution 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 (2)
- Product Information: GlucaGen(R) subcutaneous, intramuscular, intravenous injection, glucagon subcutaneous, intramuscular, intravenous injection. Boehringer Ingelheim Pharmaceuticals Inc (per FDA), Ridgefield, CT, 2021. DailyMed
- Koch-Weser J: Potentiation by glucagon of the hypoprothrombinemic action of warfarin. Ann Intern Med 1970; 72:331-335. PubMed
Keep reading about Warfarin
Keep reading about Glucagon Injection / Solution
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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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