Which of the following is a sign of an allergic reaction?

Itching and redness of the skin are characteristic signs of an allergic reaction. When the body comes into contact with an allergen, the immune system may overreact, leading to the release of histamines and other chemicals. These substances result in inflammation and irritation of the skin, which manifests as itching, redness, and sometimes swelling.

Recognizing these symptoms is crucial in identifying allergic reactions early, allowing for prompt treatment. Other options mentioned may indicate different health issues; for example, fever and chills often suggest an infection, while coughing and sneezing could be associated with respiratory conditions or irritants rather than a direct allergic response. Dry mouth may occur due to various reasons, including dehydration or medication side effects, but typically does not signify an allergic reaction.