Which of the following is a sign of anaphylaxis in children?

Hives and difficulty breathing are classic signs of anaphylaxis in children, a severe and potentially life-threatening allergic reaction. Anaphylaxis is characterized by a rapid onset of symptoms following exposure to an allergen, which can include foods, medications, insect stings, or latex.

Hives, or urticaria, present as raised, red welts on the skin and are indicative of the body's immune response to an allergen. Difficulty breathing may manifest as wheezing, stridor, or a feeling of tightness in the chest, caused by swelling in the airways or bronchospasms. These symptoms typically occur very quickly—often within minutes of exposure to the allergen—and require immediate medical intervention, including the administration of epinephrine and potentially other supportive measures.

The other options present symptoms that do not align with the acute and severe nature of anaphylaxis. Headache and fatigue are general symptoms that could relate to numerous non-allergic conditions but are not specific to an anaphylactic reaction. Fever and cough suggest an infectious process rather than an allergic one, and abdominal pain and diarrhea may point to food intolerance or a gastrointestinal issue but would not typically indicate anaphylaxis unless accompanied by severe respiratory symptoms or hives.