Rebound congestion is a constant nasal stuffiness (congestion) that develops from the overuse of nasal sprays (or drops or gels) that contain a decongestant medicine. This type of congestion occurs even when a person is not experiencing allergies or other coldlike symptoms.

Some examples of nasal spray decongestants are oxymetazoline (such as Afrin or Zicam Extreme Congestion Relief) and phenylephrine (such as Neo-Synephrine).

Rebound congestion can develop from using a nasal decongestant more times in one day or more days than the label says. As the medicine wears off, sinus membranes swell, causing congestion, and a person may respond by using a higher dose of decongestant. If the cycle continues, a person builds up a tolerance by using larger and larger doses until congestion occurs whenever the person does not take the medication.