I have had hives off and on for about 30 years. They have always been controlled nicely by antihistimines. I have had another bout with hives since this July that just wouldn't respond to anything - except pregnesone. My allergist suggested that I have blood work done to have my thyroid checked and I found that I have Hashimoto's which is an autoimmune disease like hives is. I was put on the lowest dose of synthroid and not only do I have more energy now, 6 weeks later I am hive free and on no medications for hives! I would suggest that anyone who is suffering from hives be tested for thryoid antibodies which would indicate Hashimoto's thyroiditis.