NBEO Pharmacology Practice Exam 2026 – Complete Study Guide

Antihistamines are particularly effective for acute allergic reactions due to their mechanism of action. Acute allergic responses, such as those seen in conditions like anaphylaxis or immediate hypersensitivity reactions, are characterized by a rapid onset of symptoms triggered by the release of histamine from mast cells and basophils. Antihistamines work by blocking the H1 receptor, preventing histamine from exerting its effects, which helps alleviate symptoms like itching, sneezing, and swelling.

In contrast, chronic allergic reactions tend to involve more complex immune processes that may include ongoing inflammation, other immune mediators, and a prolonged response. While antihistamines can still provide relief in these situations, they are generally less effective at addressing the comprehensive nature of chronic allergic symptoms compared to other treatments that may target multiple pathways involved in chronic inflammation.

Consequently, the effectiveness of antihistamines is particularly pronounced in acute situations where rapid intervention is necessary to counteract the immediate actions of released histamine. This is why the statement indicating they work better for acute allergic reactions is accurate.