A nurse is collecting data from a client who has gout and is taking allopurinol. Which of the following adverse effects should the nurse identify as the priority to report to the provider?

A. Rash. A rash while taking allopurinol can indicate a serious hypersensitivity reaction, including Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN). These life-threatening conditions involve widespread skin blistering, mucosal involvement, and systemic symptoms. Immediate discontinuation of allopurinol and medical intervention are required to prevent severe complications. B. Diarrhea. Mild gastrointestinal disturbances, including diarrhea, are common with allopurinol use. While bothersome, diarrhea is not life-threatening and can often be managed by adjusting the dose or taking the medication with food. It does not require immediate discontinuation unless severe or persistent. C. Nausea. Nausea is a common, mild side effect of allopurinol that usually resolves with time or by taking the medication after meals. It is not an emergency and does not require urgent intervention unless accompanied by other concerning symptoms such as vomiting or severe abdominal pain. D. Metallic taste in mouth. A metallic taste can occur with allopurinol use but is not harmful. It is a minor side effect that does not indicate toxicity or severe adverse reactions. Clients can be reassured that this effect is temporary and not a reason to stop the medication.