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The respiratory system is responsible for mediating gas exchange between the external environment and the bloodstream. The upper respiratory tract conducts air to the lower respiratory passages and ultimately to the lungs. It also humidifies and conditions inspired air and serves to protect the lungs from harmful substances. In the lungs, gas exchange takes place between the alveoli and the pulmonary circulation.

The drugs discussed in this chapter are directed primarily at maintaining proper airflow through the respiratory passages. Agents that treat specific problems in the lungs are not discussed here but are covered in other areas of this text. For instance, Section 8 (Chapters 33 to 35) includes drugs used to treat infectious diseases of the lower respiratory tract and lungs.

The respiratory agents presented here are divided into two primary categories. The first group includes drugs that treat acute and relatively minor symptoms, such as nasal congestion and coughing, or health conditions, such as seasonal allergies with their respective symptoms. The second category includes drugs that treat more chronic health conditions, such as bronchial asthma, chronic bronchitis, and emphysema.

Drug therapy can be critical in helping these patients breathe more easily and become more actively engaged in respiratory muscle training and various forms of aerobic and strengthening exercises. Patients will be more engaged in rehabilitation activities if these medications improve difficult and labored breathing and reduce the anxiety that occurs when patients feel they “cannot get enough air.” It is of utmost importance to know that there are many over-the-counter (OTC) drugs used to treat the symptoms related to the upper respiratory and allergy conditions. Some of these drug classes have very benign side effects (if any at all), while others have the potential to cause serious side effects, such as elevating heart rate and pressure or causing delirium. Since many of the drugs are over-the-counter, there is also greater potential for drug-drug interactions as these required prescription interaction checks many times do not include OTC drugs.


The drugs presented below are used to treat symptomatic coughing and irritation resulting from problems such as the common cold, seasonal allergies, and upper respiratory tract infections. Often, several different agents are combined in the same commercial preparation; for example, a decongestant, an antitussive, and an expectorant may be combined and identified by a specific trade name. Also, agents within a specific category may have properties that overlap into other drug categories. Certain antihistamines, for instance, may also have antitussive properties.


Antitussive drugs suppress coughing associated with the common cold and other minor throat irritations. When used to treat cold and flu symptoms, these drugs are often combined with aspirin or acetaminophen and other respiratory tract agents.1,2 Antitussives are typically recommended for ...

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