Hypersensitivity to an allergen is associated with ................

Antihistamine pills are used to nullify:

Which of the following is a symptom of an allergy?

What is the term for the exaggerated response of the immune system to certain antigens present in the environment?

The function of $IgE$ is

Assertion : Mast cells in the human body release excessive amounts of inflammatory chemicals,which cause allergic reactions.
Reason : Allergens in the environment on reaching human body stimulate mast cells in certain individuals.