Can an anaphylactic reaction to a substance that had previously never been a problem develop later in life?  Recently I've been having attacks of excrutiatingly itchy hives on inside my throat/ear canal (they'll wake me up or keep me from being able to sleep, but fortunately they haven't been so bad as to cause swelling that restricts breathing); itchy, swollen eyes; suspected angioedema on my hands and forearms; mild to moderate asthma attacks; and sneezing several times a day. I have not been able to pin down a particular trigger, but have been tested several times over the course of 40 years as an relatively severe asthmatic and know I'm allergic to a wide variety of things. I avoid contact with the ones that cause the greatest problems (animal dander, certain spices, citrus, molds, etc.), but have always just tolerated and treated myself for the symptoms I get from the less severe ones (foods, pollen, dust, etc.).  I get some relief from strong antihistamine eye drops that I use inside my ears and throat, as well, and find that Melagel (tea tree oil) really helps my skin. My concern is that I may be developing a more severe reaction to something I had previously not had a serious problem with. Is that common among allergic people?