★★★★★
My little rescue cat suffered from blocked nasal passages after having recurrent infections before he was rescued. We couldn't stop the nasal infections unfortunately but I found that he seemed to get headaches and would ask me to rub his face in an unusual way. So I tried sprinkling a tiny amount of NAC (N-acetylcysteine) on his food once a day and he stopped asking for face massages and seemed better.
I use NAC myself for sinus headaches. I found a scientific research paper showing a sprinkling was safe for cats. It is also used for treating respiratory inflammation and FIV in cats. If you look it up you will see vets use it. I used human-grade NAC with no additives.
