Which of these is a symptom of allergic reactions?

Chest tightness is indeed a symptom of allergic reactions, particularly in cases where the reaction affects the respiratory system, leading to conditions such as asthma or anaphylaxis. During an allergic reaction, the body releases histamines and other chemicals in response to an allergen, which can result in inflammation and constriction of the airways. This can cause a feeling of tightness in the chest, difficulty breathing, and wheezing.

Other symptoms of allergic reactions may include hives, itching, and swelling in various parts of the body. While increased heart rate, nausea, and fever can also be associated with certain medical conditions, they are not specific symptoms of allergic reactions. Increased heart rate may result from anxiety or a response to inflammation, nausea can arise from various gastrointestinal issues, and fever typically indicates an infection rather than an allergic response.