Decongestant nasal sprays are not addictive, as they do not cause the physiological cravings that define addiction, as stated by Mayo Clinic. When overused, these sprays can become less effective, leading to further overuse to control congestion. This "rebound congestion" is reversible.
Overuse of nasal spray makes the lining of the nose less responsive to the decongestant and may lead to increased application to combat this effect. Rebound congestion can occur through overuse or upon cessation of use, says Mayo Clinic. Limiting use of decongestant nasal sprays to no more than five consecutive days can prevent this effect from occurring.