allergic urticaria
"I've had seriously awful hives and angioedema for 3 months and tried everything on my own to lessen my symptoms, even taking Benadryl around the clock. I went to my doctor who prescribed this and warned it would make me drowsy when I took it. For the first time in 3 months I've had hardly any hives (though they aren't completely gone, but much easier to handle) and I wasn't drowsy at all (maybe because I'm used to taking all the Benadryl and fighting drowsiness). I haven't had any side effects."