Two months after taking nitrofurantoin for a bacterial infection, a client reports the onset of severe, watery diarrhea to the home care nurse. How should the nurse respond?

D advise that the infection has returned, and additional medication will be needed. C Offer instructions about the use of an over-the-counter antidiarrheal medication. B Explain that the diarrhea may be an adverse effect that requires further evaluation. A Determine if the full course of the initial prescription of medication was taken.