A nurse is assessing a client who has a urinary tract infection and is receiving cefaclor. The nurse should monitor the client for which of the following adverse effects of the medication?

A. Hypoglycemia is not a recognized adverse effect of cefaclor, which is a second-generation cephalosporin antibiotic. Hypoglycemia is usually related to insulin or oral antidiabetic medications, and monitoring blood glucose is not a routine concern for clients receiving cefaclor unless they have underlying diabetes or other risk factors. B. Blurred vision is not associated with cefaclor therapy. Visual disturbances are more commonly linked to medications such as antihistamines, anticholinergics, or certain diuretics, not cephalosporins. C. Photosensitivity reactions are characteristic of some antibiotics, including tetracyclines and fluoroquinolones, but cefaclor rarely causes this effect. While patients should generally practice sun safety, photosensitivity is not a primary concern with cefaclor. D. Diarrhea is the most common adverse effect of cefaclor. This occurs because the antibiotic alters the normal intestinal flora, which can result in loose stools, abdominal cramping, and, in severe cases, Clostridioides difficile–associated diarrhea. Persistent or bloody diarrhea requires immediate medical attention, as it may indicate a more serious infection or complication.