Which of the following is a common symptom of foodborne illness?

Nausea is commonly recognized as a key symptom of foodborne illness because it is often triggered by the ingestion of contaminated food or drink. Foodborne pathogens, such as bacteria, viruses, and parasites, can irritate the gastrointestinal tract, leading to nausea as a prominent response. This symptom serves as the body’s way of signaling distress due to potentially harmful substances in the digestive system.

While headache, fatigue, and allergic reactions can also occur in various situations, they are not as directly associated with foodborne illnesses as nausea is. Headaches can arise from dehydration or other causes, fatigue may result from various health conditions or lifestyle factors, and allergic reactions are specific to individuals' sensitivities rather than a general symptom of foodborne illness. Thus, nausea stands out as a primary and common symptom when discussing foodborne illnesses.