I've had uncontrollable hay fever ever since I was six years old. I had weekly shots for 9 years and took two pills every day of the season. It was still not completely controlled.
Thirty years ago I became a vegetarian because a friend told me meat produces histamine in the body and when you have hay fever you take anti-histamine pills.
Well, was I amazed at the change. My suffering went way down. A couple of years later I discovered that Vitamin C in mega doses acted as an anti-histamine with no side effects. Well, I was further amazed at the change.
So here are some things you might want to do if you do have allergies:
1. Just before and during the hay fever season eat vegetarian style.
2. Start taking 2000 mg of Vitamin C (spread the dose over the day, or order time-released versions here: Swanson First Time Customer Coupon - $5.00 Off 
When your hay fever hits, take about 500 to 1,000 mg of Vitamin C every 5 to 10 minutes. At some point your hay fever symptoms will stop. If they start again, keep taking the C as I described.
You don't have to be concerned about taking too much Vitamin C for several reasons. First, it gets used up immediately whenever the body is under stress and a hay fever attack is an attack. Second, Vitamin C is water-soluble so it doesn't collect in the body. Third if you do take too much Vitamin C, you can get diarrhea so just reduce the dosage.
In 30 years of doing this I've never had a problem with C.
