Which of the following is an example of an oral decongestant?

Pseudoephedrine, commonly known by brand names such as Sudafed and Nexafed, is classified as an oral decongestant. Its mechanism of action involves stimulating adrenergic receptors, leading to vasoconstriction in nasal blood vessels, which reduces nasal congestion. This makes pseudoephedrine effective for alleviating symptoms associated with conditions like allergic rhinitis and sinusitis.

In contrast, oxymetazoline (Afrin) is a topical decongestant, typically delivered via a nasal spray, which, while effective for short-term relief of nasal congestion, does not fall under the oral category. Montelukast is a leukotriene receptor antagonist primarily used to manage asthma and allergic rhinitis but does not possess decongestant properties. Cromolyn is a mast cell stabilizer used in nasal sprays for allergic rhinitis but, like montelukast, is not classified as a decongestant. Thus, pseudoephedrine stands out as the correct example of an oral decongestant among the options provided.