Which symptom may indicate a food allergy?

The presence of hives is a significant symptom that may indicate a food allergy. Hives, also known as urticaria, are raised, itchy welts on the skin that often result from an allergic reaction to food or other allergens. When the body encounters an allergen, it can trigger the immune system to release histamines, leading to various allergic symptoms, including hives. This response is a key indicator that the body is reacting to a specific food substance, making it crucial for identifying potential food allergies.

In contrast, while nausea, headache, and fatigue can occur due to various conditions, they are not specific indicators of food allergies. Nausea can result from food intolerance, ingestion of spoiled food, or other gastrointestinal issues. Headaches may arise from dehydration, stress, or various medical conditions and are not typically associated directly with food allergies. Similarly, fatigue can have multiple underlying causes, including but not limited to diet, hydration, and sleep quality, and is not a common standalone symptom of a food allergy. Thus, hives distinctly signal an allergic response, making it the most relevant symptom in the context of food allergies.