👉 Antihistamine is a medication that works by blocking the action of histamines, which are chemicals produced in the body that cause allergic reactions. Histamines are natural substances produced in response to allergens and irritants, such as pollen or dust, and they can trigger an allergic reaction. Antihistamines work by blocking or neutralizing these effects, reducing symptoms such as sneezing, itching, coughing, and runny nose. Antihistamines come in various forms, including