Upper Respiratory Drugs: Decongestants

Decongestants activate α-adrenergic receptors, constricting small blood vessels in nasal membranes. This vasoconstriction opens clogged nasal passages and facilitates sinus drainage, relieving congestion caused by allergies, colds, sinusitis, and upper respiratory infections. The mechanism works by mimicking sympathetic nervous system stimulation.

Decongestants are classified as β-phenylethylamine derivatives or imidazoline derivatives. β-phenylethylamine derivatives like epinephrine, phenylephrine, and pseudoephedrine act on α1-adrenoreceptors. Imidazoline derivatives such as oxymetazoline, naphazoline, tetrahydrozoline, and xylometazoline act on α2-adrenoreceptors, both producing vasoconstriction.

Topical decongestants should not be used for more than three consecutive days to avoid rebound nasal congestion, a phenomenon where congestion returns or worsens after discontinuing the medication. While they provide short-term relief, prolonged use can lead to dependency and worsen symptoms upon cessation.

Topical decongestants may occasionally cause nasal burning, stinging, and dryness, though these effects are typically mild and temporary. These local side effects are generally less concerning than systemic effects, making topical formulations a safer option for short-term use in most patients.

Oral decongestants provide longer-lasting relief than topical forms but are systemically absorbed, causing potential systemic side effects. These include nervousness, tachycardia, blurred vision, vomiting, and insomnia. Patients with cardiovascular disease and uncontrolled hypertension require careful monitoring due to cardiovascular stimulation risks.

Most decongestants are available over the counter in multiple forms including nasal sprays, nasal drops, and oral tablets. Topical formulations deliver medication directly to nasal passages for rapid local relief, while oral forms provide systemic distribution for longer-lasting effects across the upper respiratory tract.

Patients with cardiovascular disease and uncontrolled hypertension require special consideration when using oral decongestants because these agents cause cardiovascular stimulation. Healthcare providers should discuss systemic side effects like nervousness, tachycardia, and insomnia with these patients before recommending oral decongestant therapy.