I did a post of my side effects last night, and had to question if stop taking the Singulair which did help relieve my really bad sinus headaches I get with the fog, when I woke up this morning to fog and a headache, but the answer is still yes. One thing that I have found that have helped me were some suggestions I got from reading a book called The Sinus Cure: 7 Simple Steps to Relieve Sinusitis and Other Ear, Nose, and Throat Conditions, available from Amazon or bookstores. I also found the Grossan Hydro Pulse Nasal and Sinus Irrigation System a huge help, especially greatly reduces problems I get with phlegm. I don't know if this info helps anybody, but I wanted to pass it on.