What is a sign of a severe allergic reaction?

Hives are a significant indicator of a severe allergic reaction, often referred to as anaphylaxis. This condition occurs when the immune system overreacts to a substance, leading to widespread symptoms that can include swelling, difficulty breathing, and a dramatic drop in blood pressure. Hives, which manifest as raised, itchy welts on the skin, are a classic symptom of this overreaction, indicating that the body is experiencing a systemic response to an allergen. Recognizing hives is crucial for timely intervention, as they may accompany other severe symptoms that necessitate immediate medical attention.

Other symptoms like nausea, fever, and sweating can result from various conditions and are not specific signs of a severe allergic reaction. While nausea might accompany some allergic reactions, it is not an indicator of severity in the same way hives are. Fever can suggest an infection or other illness, and sweating may occur due to anxiety or exertion, but these do not directly point to an allergic response. Thus, identifying hives allows for a more accurate assessment of the severity of an allergic reaction and the potential need for emergency care.