Antihistamines

Antihistamines are first-line pharmacologic agents used to manage allergic rhinitis, urticaria, conjunctivitis, and mild anaphylactic reactions by competitively blocking H1 or H2 histamine receptors. This category covers first-generation agents such as diphenhydramine and second-generation options including cetirizine, loratadine, and fexofenadine. Articles address appropriate dosing schedules, common adverse effects like sedation and anticholinergic burden, drug interactions, and contraindications in hepatic or renal impairment. Guidance also extends to pediatric dosing considerations, pregnancy safety classifications, and clinical indicators warranting referral to an allergist or emergency care.