What is the primary use of antihistamines?

Antihistamines are primarily used to relieve allergy symptoms by blocking the action of histamine, a chemical in the body that is responsible for allergy-related symptoms. When allergens, such as pollen or dust mites, enter the body, they trigger the release of histamine, leading to symptoms such as sneezing, itching, and a runny nose. By counteracting the effects of histamine, antihistamines effectively reduce these symptoms, providing relief to individuals suffering from allergic reactions.

While antihistamines might have some ancillary uses in other conditions such as motion sickness or insomnia due to their sedative properties, their primary function remains focused on addressing allergic responses. Other choices in the question, such as treating depression, managing pain, or controlling blood pressure, fall outside the primary role of antihistamines, which firmly establishes their specific therapeutic application in allergy relief.