Which symptom is associated with severe anaphylactic reactions?

Swelling of the face and/or tongue is a hallmark symptom of severe anaphylactic reactions. Anaphylaxis is a life-threatening allergic reaction that can occur rapidly after exposure to an allergen. The swelling, also known as angioedema, is caused by the release of histamines and other chemicals in response to the allergen. This swelling can obstruct the airway, making it critical to recognize and respond promptly to this symptom.

In contrast, loss of appetite, headache, and abdominal pain may occur in various other medical conditions but are not specific indicators of anaphylaxis. While abdominal pain can sometimes present due to other allergic reactions or gastrointestinal disturbances, it does not represent the acute danger posed by airway swelling in anaphylaxis. Thus, recognizing the swelling of the face and/or tongue is vital for early intervention and treatment during severe allergic reactions.