What is the function of antihistamines?

Antihistamines function primarily by blocking the effects of histamine, a chemical that plays a central role in the body's immune response, particularly during allergic reactions. When histamine is released from mast cells and basophils, it binds to histamine receptors and can cause symptoms such as itching, sneezing, runny nose, and swelling. Antihistamines work by binding to these receptors, thus effectively preventing histamine from exerting its action. This action helps alleviate the symptoms associated with allergies and hay fever by counteracting the histamine's effects.

The other options do not accurately describe the role of antihistamines, as they suggest functions that are opposite to those of antihistamines. Antihistamines are specifically designed to mitigate the effects of histamine, rather than promote its production or enhance allergy symptoms, thereby serving as an essential tool in the management of allergic reactions and related conditions.