What is the effect of antihistamines on allergic reactions?

• A. They enhance the severity of the reaction
• B. They block histamine receptors to reduce symptoms
• C. They increase the immune response
• D. They have no significant effect on allergic reactions

Answer: (B)

Antihistamines are specifically designed to combat the effects of histamine, a chemical released during allergic reactions that contributes to symptoms such as itching, sneezing, and runny nose. By blocking histamine receptors, particularly the H1 receptors, antihistamines effectively reduce these symptoms. This receptor blockage prevents histamine from exerting its effects, thus alleviating discomfort during an allergic reaction.

Their role is crucial in managing allergic responses, making them widely used in treating conditions like allergic rhinitis, urticaria, and conjunctivitis. This mechanism of action distinguishes antihistamines as a first-line treatment in alleviating the common symptoms associated with allergies. In contrast, options that suggest enhancement of reactions or increased immune responses do not align with the established pharmacological action of antihistamines.