Saline solutions aren't dangerous. They are just salty water.
I have a deviation in my nose, so my nose gets stuffy a lot. Unfortunately, saline solutions don't make my nose comfortable; they don't do anything to me actually ! But that's me
I wrote about the drugged nasal spray for a more serious case. (I have read this as a vet's advice in one of the web sites). Drugged nasal sprays work for a few days but as Hissy said they will cause more inflamation of the nasal membrane when they are over used & will cause more stuffiness. So the user will want to use more nasal spray to get comfortable, thus it will mean more inflamation, more spray, more inflamation, more......
And please don't think that I'm trying to prescribe any drugs like a vet. Lysine is an amino acid supplement which is found to work against the herpes Virus replication mechanism. I have learned about it from internet (from veterinarian sites) but my vet didn't know about it. That's why I mentioned it.
Your vet always knows better about your cat(s)