Cisplatin Injection and Warfarin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Warfarin
Cisplatin Injection
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 INR
Interaction Deep Dive
Concomitant use of CISplatin together with warfarin may result in increased INR and risk of bleeding. Two case reports have described elevations in INR following addition of CISplatin in patients previously stable on warfarin1. Monitor INR when starting, stopping, or changing the dose of the concomitant drug in patients receiving warfarin therapy 2.
Why it happens (mechanism)
Unknown
Literature reports
2 reports — tap to read
a) Increased INR without bleeding was reported on day 3 of 2 consecutive cycles of irinotecan and CISplatin therapy in a 50-year-old woman with ovarian carcinoma and DVT. The patient was diagnosed with ovarian cancer, DVT of the femoral and internal iliac veins, cerebellar thrombosis, bilateral kidney thrombosis, and DIC and treated with warfarin, continuous heparin, neoadjuvant paclitaxel plus CARBOplatin, and surgery. Concomitant medications included warfarin 3.25 mg/day (goal INR 2 to 2.5) and aspirin 100 mg/day with the chemotherapy regimen of irinotecan 60 mg/m(2) on days 1, 8, and 15 plus CISplatin 60 mg/m(2) on day 1 repeated every 4 weeks and the supportive agents of granisetron, dexamethasone, and aprepitant began. On day 3 of irinotecan plus CISplatin, INR increased from 2.12 to 3.43; warfarin was held for 1 dose and no bleeding was reported. A similar increase of INR occurred on day 3 during the second chemotherapy cycle. The patient reported mild nausea and anorexia with a 30% reduction of food intake for a few days after CISplatin dosing 1.
b) A 43-year-old woman with recurrent peritoneal and liver metastasis of uterine cervical adenocarcinoma experienced an increased INR without bleeding around day 3 during 3 consecutive cycles of irinotecan and CISplatin therapy. Concomitant medication included warfarin 2 mg/day (goal INR 1.2 to 1.5) when the chemotherapy regimen of irinotecan 60 mg/(m)2 on days 1, 8, and 15 plus CISplatin 60 mg/(m)2 on day 1 repeated every 4 weeks and the supportive agents of granisetron, dexamethasone, and aprepitant began. On day 3 of the second cycle of irinotecan plus CISplatin, INR increased from 1.3 to 1.77; warfarin was continued without change and INR remained elevated at 1.88 on day 8, and INR returned to within goal range by day 15 of the chemotherapy cycle. A similar increase of INR occurred during the third and fourth chemotherapy cycles. The patient reported mild nausea and anorexia with a 20% reduction of food intake for a few days after each CISplatin dose 1.
Common questions
Can I take Cisplatin Injection and Warfarin together?
Increased INR Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cisplatin Injection and Warfarin 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 "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 Cisplatin Injection or Warfarin 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)
- Yano R, Kurokawa T, Tsuyoshi H, et al: Transient elevation of international normalized ratio during cisplatin-based chemotherapy in patients who are taking warfarin. Ann Pharmacother 2011; 45(10):e55. PubMed
- Product Information: COUMADIN(R) oral tablets, intravenous injection powder lyophilized for solution, warfarin sodium oral tablets, intravenous injection powder lyophilized for solution. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2011. DailyMed
Keep reading about Warfarin
Keep reading about Cisplatin Injection
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