If you suffer from an acute infection, you can use a decongestant nasal spray for a few days without hesitation. But after a week of continuous use at the latest, the so-called rebound effect becomes more and more likely: the nasal mucosa now gets used to the helper from the outside and swells faster and faster, so it needs more and more nasal spray to reduce swelling as desired.
Rebound effect
Learn more about the rebound effect.