If your eyes are itchy and antihistamine don't help, look for antihistamine eye drops. You can get them in the supermarket or ask your pharmacist.
Regarding antihistamine tablets
Chloramphnamine is an antihistamine active ingredient. And
Diphenhydramine (brand name Benadryl). As others on gransnet have mentioned there are loratidine and cititizine too. Brand names cane be so expensive. I usually get my antihistamines in the supermarket or wilkos, etc. Recently I have started getting 6 months supplies on the internet, if the price works out cheaper than the supermarket.
If it is an ongoing problem in summer time, start taking antihistamines in April already and keep taking them through until the end of summer. Each person reacts differently. E.g cititizine may cause drowsiness for some people, including me, but other people (including DH) are not affected.
Sometimes if my hayfever is too bad to manage, my GP will prescribe me something stronger, only available on prescription. Ditto stronger antihistamine eye drops.
All the best.