Certified Pharmacy Technician (CPhT) Practice Exam

Antihistamines are medications specifically designed to block the action of histamine, a substance in the body that contributes to allergic symptoms such as sneezing, itching, runny nose, and hives. When a person encounters an allergen, histamine is released from certain cells in the immune system, leading to these characteristic allergic reactions. By acting as antagonists to histamine at its receptors, antihistamines effectively diminish or eliminate these symptoms.

In contrast, decongestants work by narrowing the blood vessels in the nasal passages, leading to reduced swelling and congestion, but they do not directly influence histamine. Analgesics are pain relievers, such as acetaminophen or ibuprofen, and do not impact allergic reactions. Antibiotics target bacterial infections and do not have any effect on histamine or allergy symptoms. Thus, the specific action of antihistamines in blocking histamine makes them the correct choice for alleviating allergy symptoms.