Is it possible to develop hay fever as an adult?

[nkf]

Because I seem to have all the symptoms.

Yes. It is possible.
Get a skin test from your GP.

Yes. My bro has it really badly now but didn't have it at all until he was about 20.

Okay. I'll go to the doctor. It's making me miserable to be honest.

Spent a lovely day in the country today and now I can't stop sneezing and my eyes and nose hurt.

Yes, I developed it last year at 35 !
I'd always lived in fairly urban places until 6 years ago when we moved to here which is pretty rural with a wood at the back of us. Since last year I've had horrible hayfever, only really twigged to it at the end of the summer. I must admit - I didn't really think it could make you feel quite so awful as it does. I get a thumping headache, sore eyes and sneezes++.
I think it was the eczema society website has some hints and tips for minimising symptoms - things I hadn't considered (over and above the usual) - tie long hair back (traps pollen), wash hair daily (ditto), wear sunglasses, vaseline around nostrils to trap pollen, keep windows closed on a night.
There are more but those spring to mind at the mo. Hope you feel better with the anti-histamines.
HTH

Yes and it can disappear again too! I had it first when I was pg with dd1 and then it went just after dd2!

I hope it disappears. Do you think it's unwide to buy something from the chemist before getting a proper diagnosis from the GP.

Yes - I did about 3 years ago at the grand age of 40.

The main symptoms were gravelly eyes (horrible), which cleared up with antihistamines. I don't have it all the time - just a few days a year when I medicate, and I haven't discovered a pattern yet.