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

A. Determine if the full course of the initial prescription of medication was taken: This information alone does not address the immediate concern of severe watery diarrhea, which may indicate a serious complication rather than incomplete treatment. B. Offer instructions about the use of an over-the-counter (OTC) antidiarrheal medication: OTC antidiarrheals can be harmful if the diarrhea is caused by a serious infection such as Clostridioides difficile. Suppressing diarrhea without evaluation can delay appropriate treatment and worsen the condition. C. Advise that the infection has returned and additional medication will be needed: Assuming a recurrent infection without diagnostic evidence risks inappropriate treatment. The diarrhea may be due to antibiotic-associated colitis or other causes unrelated to infection recurrence. D. Explain that the diarrhea may be an adverse effect that requires further evaluation: Severe watery diarrhea occurring after antibiotic use can indicate a serious adverse effect like C. difficile colitis. Prompt recognition and medical evaluation are essential to prevent complications and ensure proper management.