Allergies: in particular, hayfever and how to treat it?

[cam1]

It's practically summer now and as usual I'm starting to develop symptoms of hayfever, which sucks because summer is the best time of the year! Do you know any ways to treat this EFFECTIVELY, I've tried the mainstream tablets, sprays and so on and either  1. It doesn't work, or 2. It works for a short period of time, and then my body becomes used to it and it no longer works.