Which of the following can indicate a serious allergic reaction?

The presence of itching and hives is a key indicator of a serious allergic reaction, often referred to as urticaria. These symptoms arise when the body’s immune system overreacts to an allergen, causing the release of histamine and other chemicals that lead to inflammation and irritation of the skin. Itching is a common reaction to allergens, and hives are raised welts that can vary in size and may appear and disappear rapidly.

This response is particularly concerning if it occurs alongside other symptoms such as difficulty breathing, swelling of the face or throat, or a rapid heartbeat, which could indicate anaphylaxis, a life-threatening allergic reaction. The urgent nature of these symptoms underscores the need for immediate medical attention.

In contrast, sunburn, peptic ulcers, and frequent headaches do not typically signal an allergic reaction. Sunburn results from skin damage due to UV radiation, peptic ulcers are related to stomach acid and may be caused by factors such as infection or NSAID use, while frequent headaches can stem from a variety of non-allergic conditions ranging from stress to dehydration or migraines. These conditions do not share the same immunological response as allergic reactions, making itching and hives the most critical sign of a major allergic response.