allergic rhinitis
"Since I moved into a new house I began having respiratory problems, occasional wheezing and breathing difficulty with exertion. Allergies came back negative and antihistamines had no effect so my dr gave me an inhaler and sinulair. I started on singulair first to avoid taking extra medications I might not need. 

From the first day on Singulair the mild symptoms I had improved but I also had a mild headache most of the time.  By the 3rd day the headache became horrible, so much pain that I felt nausua and chills.  I will not be taking it again ever."