Which of the following symptoms is commonly associated with allergic conjunctivitis?

Itching is a hallmark symptom of allergic conjunctivitis. When the eyes are exposed to allergens such as pollen, pet dander, or dust mites, the immune system responds by releasing histamines and other chemicals. This reaction leads to inflammation of the conjunctiva (the membrane covering the eye and inner eyelids) and results in intense itching.

While other symptoms can be present in various conditions, itching specifically indicates an allergic response, making it a key distinguishing feature of allergic conjunctivitis. Vision loss is typically associated with more serious conditions affecting the eye, nausea is not directly related to eye symptoms, and headaches can occur due to various factors but are not a hallmark of allergic conjunctivitis. Therefore, the presence of itching directly points to allergic conjunctivitis as a likely diagnosis.