A nurse is assessing a client who is taking oxacillin to treat an infection. The nurse should recognize which of the following findings is a manifestation of an allergic reaction?

A. Diarrhea: Diarrhea is a common side effect of antibiotics like oxacillin but is not typically a sign of an allergic reaction. It is more likely related to gastrointestinal irritation or disruption of the normal gut flora. B. Dark urine: Dark urine can indicate dehydration, liver dysfunction, or hematuria, but it is not a typical sign of an allergic reaction to oxacillin. It is important to assess further to determine the cause. C. Fever: While fever can occur with an infection, it can also be a nonspecific side effect of oxacillin. However, fever alone is not a definitive sign of an allergic reaction. D. Pruritus: Pruritus (itching) is a common sign of an allergic reaction. If a client develops itching after starting oxacillin, it may indicate an allergic response, and the nurse should monitor for more severe symptoms like rash, swelling, or difficulty breathing.