Early clinical manifestations of an allergic reaction include all of the following, EXCEPT:

The early clinical manifestations of an allergic reaction typically include symptoms that are indicative of a histamine response in the body, such as pruritus (itching), edema (swelling), and urticaria (hives). These symptoms are part of the immediate immune response to an allergen, as the body releases histamine and other chemicals that lead to vasodilation and increased permeability of blood vessels.

Stridor, on the other hand, is a high-pitched, wheezing sound that occurs due to airflow obstruction in the upper airways, which is often associated with more severe allergic reactions, such as anaphylaxis or significant airway edema. It usually develops later and indicates a serious condition requiring immediate medical attention. Therefore, while stridor can occur as an allergic reaction progresses, it is not considered an early manifestation of the reaction itself.

Understanding this distinction between early symptoms and those that indicate a more advanced or severe reaction can help in recognizing the severity of allergic responses and guide appropriate interventions.