Which symptom indicates that a client is experiencing an allergic reaction during a blood transfusion?

Urticaria, commonly known as hives, is a skin reaction that manifests as raised, itchy welts and is a classic symptom of an allergic reaction, particularly during a blood transfusion. This reaction occurs when the immune system identifies proteins in the transfused blood as harmful, leading to an inflammatory response.

While fever, hypertension, and chills can occur during blood transfusions, they are more commonly associated with other complications such as febrile non-hemolytic transfusion reactions or transfusion-related acute lung injury (TRALI). Therefore, the presence of urticaria is a more specific indication of an allergic reaction, highlighting the importance of monitoring for skin changes in clients receiving blood products.