Decongestants are a type of medication that reduces congestion of the sinus and nasal passages. They are designed to ease the symptoms experienced when a person has a cold or is suffering from nasal allergies. Most decongestants are available for purchase over the counter (OTC); however some are only available with a prescription.
When the cold virus or an allergen is absorbed by the nose, the body produces a substance known as histamine. Histamine increases blood flow to the nasal area, causing blood vessels and the surrounding nasal tissue to swell up. This swelling inflames the nasal area, stimulating the production and leakage of mucus and excess fluid. The swollen membranes also limit the amount of space in the nose and nasal cavity where air can enter and exit, creating the feeling of stuffiness commonly associated with a cold or allergy.
Decongestants work by stimulating receptors in the sympathetic nervous system causing blood vessels and nasal tissue to shrink. This in turn helps reduce the body’s production of mucus and excess fluid. The reduced swelling leads to the nasal passages feeling more open and the symptoms of congestion being reduced.
Many decongestants are combined with a type of medication known as an antihistamine. An antihistamine counters the effect of histamine on the body. Therefore the antihistamine helps to reduce the cause of the swelling of nasal tissues, while the decongestant reduces the symptoms of nasal swelling.
Decongestants are generally made in two forms — oral and topical — both are equally effective. Oral decongestants are typically found in tablet, capsule, or liquid form. These usually take about 30 minutes to take effect and can be effective for up to 24 hours. It should be noted that an oral decongestant will cause blood vessels throughout the body to shrink, possibly raising an individual’s blood pressure. Those with high blood pressure or a history of heart disease should consult their health care provider before taking a decongestant.
Topical decongestants are generally found in drop or spray form and are applied directly to the user's eyes or nose. Topical medications start to work in approximately 10 minutes and can be effective for up to 12 hours. Users of topical decongestants, especially nasal spray, should not use it for more than two to three days, as prolonged use could lead to a rebound effect. When this occurs, the nasal passages are unable to remain open without the continued use of the nasal spray.