A nurse is reinforcing teaching with a client who has a prescription for oral suspension phenytoin. Which of the following information should the nurse include in the teaching?

A. Notify the provider immediately if urine turns red-brown in color. Phenytoin can cause urine discoloration, but this is not typically a cause for immediate concern. B. Obtain an annual flu vaccine while taking phenytoin. While vaccinations are important, there is no specific requirement for flu vaccination solely based on phenytoin use. C. Shake the suspension vigorously prior to pouring the medication. Phenytoin suspension should be shaken gently to ensure even distribution of the medication. D. Take an antacid with the medication to avoid gastric upset. Antacids should not be taken simultaneously with phenytoin, as they can decrease its absorption.