Decongestants and allergic rhinitis

Oral and intranasal decongestants have no role in allergic rhinitis. Although they are effective at reducing congestion, they should not be used for more than 3 to 5 days. Prolonged use of intranasal decongestants causes rebound congestion (rhinitis medicamentosa), which can take several weeks to reverse. Oral decongestants can increase blood pressure, and increase the risk of arrhythmias in people with cardiovascular disease.

Oral and intranasal decongestants are also not recommended in children younger than 6 years because of the lack of evidence for benefit and the risk of adverse effects.