I've never had hives before, they came up last night and I took an antihistamine, which is supposed to last a day. It's stopped the hives from itching and the blotches went down but new blotches have started coming up, although they're not currently itching.The antihistamine should still be in my system, I can't take another one until 11pm. Does anyone know how long they last? And are they're any signs they're getting better or worse? Thank you xx