Drug General Information (ID: DDI26BFP9A)
Drug Name			Acetaminophen		Drug Info		Warfarin		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Analgesics				Anticoagulants
Structure

Mechanism of Acetaminophen-Warfarin Interaction (Severity Level: Moderate)
Increased risk of bleeding Click to Show/Hide Mechanism Graph
Drug Name		Acetaminophen				Warfarin
Mechanism		Risk of bleeding Antiplatelet effects				Risk of bleeding Anticoagulant
Key Mechanism Factor 1
		Factor Name		Bleeding
		Factor Description		Patients may be at risk for bleeding when the outcome of a disease or disease treatment confounds the standard mechanisms for maintaining hemostasis. Signs or symptoms of abnormal bleeding include: bleeding that takes a long time to stop (including nosebleeds, bleeding gums, bleeding from cuts and abrasions, and menstrual bleeding); severe unexplained bruising, or bruising that becomes larger; blood in the urine or stool, etc.
Mechanism Description		Increased risk of bleeding by the combination of Acetaminophen and Warfarin

Recommended Action
Management		Due to the lack of safer alternatives, acetaminophen is considered the analgesic and antipyretic drug of choice for patients receiving warfarin and similar anticoagulants. However, caution is recommended during concomitant therapy, particularly if high dosages of APAP are used continuously for more than a few days, or in patients with risk factors such as ethanol consumption, old age, and malnutrition. Closer monitoring of INR may be advisable. Patients should be advised to promptly report any signs of bleeding to their physician, including pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, increased menstrual flow, vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or brown urine, or red or black stools.

References
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