Welcome in H.C.M.
I have gone through your query regarding nasal obstruction
and prolong use of decongestant drop by your nephew.
Here I would like to say that prolong use of these decongestants will give rise to Rhinitis Medicamentosa
. Therefore prolong use of these should always be avoided and you should consult your ENT doctor to examine your nephew ad find out the cause of nasal obstruction and treat them accordingly.