Is singulair (montelukast) effective by itself?

Yes: Montelukast is effective as a "controller" medication in mild asthma and also is approved by the fda for allergic rhinitis (hay fever). It may be used alone or with other allergy/asthma medications. All ashtmatics should have a "reliever inhaler" in addition to their controller medication.

Can be: It can be. Only way to know is to use it and see. If not, then you will need additional medications. Personally, I have not found it to be effective alone. Oftentimes i need to combine it with another medication or add it on as adjunctive therapy.

Not in my opinion: I have seen 100's of patients on singular and I can't tell it does much at all. I think if you're going to be on a drug in this class for asthma, zyflo is a much better choice.