Repeating what everyone else here has said, Saline... our allergist has us on it...store brand, & I use a sharpie to put the first initial of each of our names on the bottles in the cabinet!
That said, he also wants us on Flonase, Nasonex or Astelin... he's not choosy, just gives us samples when we see him and writes the script for whichever of them has a coupon or a special offer, like your first script gets a rebate.
My son & hubby both have allergies, and I am prone to sinus infections b/c of a deviated septum but don't want surgery. Our allergist says if we're not going to live by the ocean where there's naturally saline in the air, and the air is cleaner and fewer pollen-bearing trees, this is the next best thing (he's half joking of course, but it's working for us!)
Also, when your son's feeling a cold coming on, have him do the Zicam swabs. It's zinc, which is a virus fighter, and it does help to shorten the longevity of a cold, and since it's swabbed into the nose, should also help to prevent the virus from settling into the sinuses and turning into an infection.
Knock wood, so far so good for me this season ~ zicam has thus far prevented my colds from turning into sinus infections, and the colds have been very minor!
Good luck!
Oh, and regarding the posts about the nasal sprays, wasn't it Afrin? My ex father in law was also one who became addicted to it.
I am fairly certain the prescription sprays and probably otc ones too, don't contain "that" ingredient any longer... this was a looooong time ago, like 25-30 years.
Right?