Image of the Week: Progressive headache, dizziness, and confusion in a 76-year-old man

A 76-year-old man presents with a progressive headache, dizziness, and confusion after falling out of bed the previous night. After undergoing a mechanical valve replacement 11 years ago, he was prescribed warfarin, which he takes daily. A CT scan reveals a subdural hematoma and the patient’s INR measures 7.5. Which of the following is most likely to increase the anticoagulant effect of warfarin? Learn more about this case, take the quiz, and join the conversation on Figure 1.

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