A nurse is providing teaching about dietary supplements to a client who has erectile dysfunction and has been prescribed nitroglycerin. Which of the following statements is the most important for the nurse to include in the teaching?

C There is not enough evidence that dietary supplements are effective for erectile dysfunction. D Dietary supplements can cause a drug-drug interaction with nitrates. A Dietary supplements have not been tested and approved by the government. B Dietary supplements may be expensive and are not typically covered by insurance.