The document breaks down drugs that work on the respiratory system into classifications such as antibiotics, antihistamines, bronchodilators, corticosteroids, decongestants, expectorants, and mucolytics. It provides details on common antibiotics like amoxicillin which is prescribed for lower respiratory infections. Antihistamines work by blocking the effects of histamine released during allergic reactions, with common over-the-counter options being Benadryl, Claritin-D, and Zyrtec. Expectorants make the respiratory tract less congested by thinning mucus, with popular brands being Mucinex and Robitussin.