A nurse is providing teaching to a client who has a new prescription for warfarin. Which of the following instructions should the nurse include in the teaching?

A. “This medication can cause back pain.": Back pain is not a common or expected adverse effect of warfarin. If the client experiences unusual pain, especially accompanied by bruising or bleeding, it may warrant further evaluation but is not directly related to the medication itself. B. "Avoid taking this medication with milk products.”: Warfarin does not interact with milk or dairy products in the way some antibiotics do. The more important dietary concern is maintaining consistent intake of vitamin K, found in green leafy vegetables. C. “Take the last dose of the day 1 hour before bedtime.": Warfarin is typically taken once daily at the same time, but timing relative to bedtime is not critical. The key point is consistency and routine INR monitoring, not the hour of the day. D. "Use an electric razor when shaving while taking this medication.": Warfarin increases bleeding risk, so using an electric razor helps minimize the chance of cuts and bleeding during shaving. This is a standard safety recommendation for clients on anticoagulants.