What are signs of an allergic reaction?

Signs of an allergic reaction primarily include urticaria, commonly known as hives, and respiratory symptoms such as mild respiratory distress. Urticaria is a classic symptom associated with allergic responses, indicating the body’s immune system reacting to an allergen. Mild respiratory distress can also occur if the reaction involves the respiratory system, often seen with inhaled allergens or allergens that enter the body through other routes.

The other options represent symptoms that may arise due to various conditions but are not specific indicators of an allergic reaction. Headaches and fever, for instance, might suggest an infection or another illness rather than an allergy. Similarly, nausea and vomiting, along with abdominal pain and diarrhea, could point to gastrointestinal issues or food intolerances rather than having direct ties to allergic responses.