I've been on Singulair for about 2 1/2 years. I take it as an addition to my allergy and asthma medications to get better control of the symptoms for both. It has worked very well for me for this purpose. I am not sure how how well it would work on its own.

FYI: The other allergy medications I take are: Allegra, Flonase & Astelin. For asthma I also take Advair 500/50 and Albuterol (as needed).