A nurse is caring for a client who is febrile. To reduce the client's fever, the nurse applies a cooling blanket. Which of the following findings indicates the client is having an adverse reaction to the cooling?

A) Flushing: Flushing can occur as the body tries to regulate temperature, but it is not typically an adverse reaction to cooling measures. B) Restlessness: While restlessness can indicate discomfort, it is not a specific sign of an adverse reaction to cooling therapy. C) Shivering: This is the correct answer. Shivering is a direct response to cold exposure and indicates that the body is trying to generate heat in response to the cooling blanket. It can be an adverse reaction as it can increase metabolic demand and may counteract the intended effects of the cooling. D) Tachycardia: Although an increase in heart rate can occur with fever or anxiety, it is not a definitive indicator of an adverse reaction to cooling. It can also be a normal physiological response.