The class of antihistamines functions primarily as what type of agent?

Antihistamines primarily function as histamine antagonists. This means that they work by blocking or inhibiting the action of histamine at its receptor sites. When histamine is released during an allergic response or other physiological reactions, it binds to histamine receptors, which can lead to symptoms such as itching, sneezing, and inflammation. Antihistamines counteract these effects by preventing histamine from binding to the receptors, thereby reducing or alleviating allergy symptoms.

This mechanism of action is crucial for the therapeutic use of antihistamines in treating allergies, hay fever, and certain types of reactions. By effectively antagonizing histamine, these medications help stabilize the body's response to allergens and provide relief from discomfort.