I used to have the injection. I think its a steriod based one (its only a last ditch if you've been munching pills for a few years to no avail), so after you have it for a few years they wont let you have it anymore because its meant to make your bones brittle or some shit. Which sucks because one injection and I could roll in grass all day with out so much as a sniff and the injection was good for 2 season's of summer! Unfortunately for me, it was the only bloody thing that worked!!
Puts a huge downer on the summer.
One things that does help a bit however, get yourself some locally made honey and eat lots of it. Gets your body used the the pollen thats in the air near you.