A 68-year-old client with atrial fibrillation on warfarin was started on trimethoprim-sulfamethoxazole for a urinary tract infection 4 days ago. The client reports new bruising on the arms and legs. The nurse reviews the electronic health record. What should the nurse do first?

The client's INR is 5.8, which is supratherapeutic and places them at high risk for bleeding, as evidenced by new bruising. The priority action is to hold the next warfarin dose to prevent further anticoagulation and immediately notify the healthcare provider for further orders, such as vitamin K administration or closer monitoring. Administering vitamin K without a provider's order is not within the nurse's scope of practice. Obtaining a urine specimen and applying ice are lower-priority actions that do not address the immediate risk of bleeding.