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Does Warfarin Interact with Levofloxacin?

Warfarin and Levofloxacin have a major drug interaction according to U.S. FDA drug labeling data. Levofloxacin may enhance warfarin effects, elevating prothrombin time and increasing bleeding risk. Monitor prothrombin time, INR, and watch for bleeding. The mechanism involves unknown; postmarketing reports indicate enhancement despite no effect observed in clinical studies. Patients taking both medications should consult their healthcare provider before starting, stopping, or changing the dosage of either drug. This information is based on official FDA drug labeling sourced from OpenFDA and the NIH National Library of Medicine.

Severity
Major
Levofloxacin Class
Fluoroquinolone Antibacterial
Management
Close medical supervision required
Data Source
U.S. FDA via OpenFDA

How This Interaction Works

The interaction between Warfarin and Levofloxacin occurs because unknown; postmarketing reports indicate enhancement despite no effect observed in clinical studies. Clinically, this means levofloxacin may enhance warfarin effects, elevating prothrombin time and increasing bleeding risk. monitor prothrombin time, inr, and watch for bleeding. This is classified as a major interaction, meaning it could cause serious harm if not properly managed. Your healthcare provider may need to adjust dosages, substitute one medication, or increase monitoring frequency.

What To Tell Your Doctor or Pharmacist

If you are taking Warfarin and your doctor is considering prescribing Levofloxacin (or vice versa), make sure to:

  • Inform your doctor and pharmacist of all current medications, including over-the-counter drugs and supplements
  • Ask whether the benefits of combining these medications outweigh the risks for your specific situation
  • Ask what symptoms to watch for that would indicate the interaction is causing problems
  • Ask how frequently you should be monitored while these are co-prescribed
  • Ask whether any dosage adjustments are needed
  • Never stop or change either medication without first consulting your healthcare provider
💊 Warfarin(Warfarin Sodium)+💊 Levofloxacin

Severity & Interaction Details

⚠️
major
Use with caution — major interaction
Serious risk of clinically significant harm. Generally avoid; if used, monitor closely.
Severity scale
MinorContra
On record
Yes
Drug A class
—
Drug B class
Fluoroquinolone Antibacterial
Source
NLP:levofloxacin

What this means in plain English

Levofloxacin may enhance warfarin effects, elevating prothrombin time and increasing bleeding risk. Monitor prothrombin time, INR, and watch for bleeding.

What the FDA label says

"Unknown; postmarketing reports indicate enhancement despite no effect observed in clinical studies"

📖 Source: NLP:levofloxacin

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Data sourced from U.S. FDA drug labeling via openFDA and the NIH National Library of Medicine. For informational purposes only. Always consult your pharmacist or physician.