18.2 : 上呼吸道疾病用药：概述

Common upper respiratory disorders like viral infections, allergic rhinitis, and congestion can be managed with drugs, such as antihistamines, intranasal steroids, decongestants, antitussives, expectorants, and mucolytics.

Antihistamines, which are H1 receptor antagonists, block histamine from binding to the H1 receptors and relieve allergic symptoms like runny nose and itching.

Intranasal steroids, inhibit mast and white blood cell responses, reducing inflammation in allergic rhinitis.

Decongestants cause vasoconstriction of small blood vessels of the nasal membranes. They open clogged nasal passages, aiding sinus drainage for colds, sinusitis, and rhinitis.

Antitussives depress the cough center in the medulla, relieving persistent coughs.

Expectorants increase respiratory secretions, loosening mucus for easier expulsion.

Conversely,  mucolytics can be chemicals or proteins that directly break down mucus, reducing its thickness and facilitating clearance.