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?

Warfarin (Coumadin) is an anticoagulant that increases bleeding risk. An electric razor prevents cuts and reduces the risk of bleeding from shaving injuries. Milk products do not interact with warfarin. Sunlight avoidance is associated with certain antibiotics and chemotherapy, not warfarin. Back pain is not a typical warfarin side effect — flank or abdominal pain may indicate retroperitoneal bleeding, which should be reported, but routine back pain teaching is not standard warfarin education.