Decongestants act in such an infant, unfortunately only conditionally good.
We have several "snot-aspirator" systems tried and this one was definitely the best. It is a flexible tube into the mouth, pushing the baby a funnel into the nostril and sucks on the hose. It creates a vacuum and the snot is collected in the abnhembaren, washable hopper.
The good thing about the system is that you can control the pressure and vacuum greatly depending Verschnufungsgrad.
Other systems that had a kind of bellows, I can not recommend it because this constant strongly (or rather weakly) generate a negative jerk.
And our little girl has suction after 5x also get used and makes the procedure more than simply endure more or less unopposed.
In addition, even the exhaust air / Rotzmenge is solid held above a kind of filter, so that nothing gets into the suction tube, therefore very easy to clean.