Congestion in the nose, sinuses, and chest is due to swollen, expanded, or dilated blood vessels in the membranes of the nose and air passages. These membranes have an abundant supply of blood vessels with a great capacity for expansion (swelling and congestion). Histamine stimulates these blood vessels to expand as described previously. Decongestants, on the other hand, cause constriction or tightening of the blood vessels in those membranes, which then forces much of the blood out of the membranes so that they shrink, and the air passages open up again.
Decongestants are critical in initiating therapy for either chronic or acute rhinosinusitis.
They can generally be divided into topical and systemic methods of delivery.
Several systemic and topical decongestants are available over-the-counter.
Systemic decongestants have many side effects, and topical decongestants can cause more congestion if used for too long.
Decongestants can relieve many symptoms and help to open up sinus passages.