I've had chronic hives for two years now. I was told that they are idiopathic and that it can last from 5-10 years. Yes, you read that right. That. Long. It *****. I also have chronic fatigue syndrome so I can't take any meds that make me drowsy so just been taking Zyrtec. I had every test done to rule out things. They sent tests to the mayo clinic and I saw rheumatologists, infectious disease, cardiologist, neurologist, gynecologist,, allergist....pretty much every doctor.