I understand that completely and when I am having a hard time I think about going back on the antihistamine. I have done it a few times but always stop after a week. The Mucinex states (in bold print) "do not take longer that 7 days". I believe one of the side effects were kidney stones.
Benadryl had side affects of "dementia & Alzheimer's". This is very concerning to me.
I have ordered an Air Purifier and better filters for my ac/heating system and will see what happens with that.