Which of the following symptoms is considered a systemic symptom of anaphylaxis?

In the context of anaphylaxis, systemic symptoms refer to those that indicate a widespread reaction in the body rather than localized symptoms. The correct answer identifies diarrhea and vomiting as systemic symptoms because these manifestations occur due to the body's overall response to severe allergic reactions.

During anaphylaxis, there is a rapid release of histamines and other chemicals into the bloodstream, which can lead to gastrointestinal distress, causing nausea, vomiting, and diarrhea. These symptoms reflect a systemic involvement of the body's immune response and can be critical indicators in diagnosing anaphylaxis, along with other signs such as difficulty breathing and swelling.

While fever, myalgia (muscle pain), and headache can occur in various medical conditions, they are not typically recognized as primary systemic symptoms of anaphylaxis. Anaphylaxis usually presents with symptoms directly related to severe allergic reactions, such as respiratory issues, skin symptoms, and gastrointestinal disturbances, which makes diarrhea and vomiting more characteristic of this condition.