I am a 35 year old female with hashimotos's Thyroiditis. I have been taking synthroid for 4 years with no problems until about 2 weeks ago. Broke out in hives. I know it is the synthroid because right after I take it I begin itching and stinging, and now some chest tightness.. Tried Armour and am having the same problem. Could it be an inactive ingredient in the meds? And, if so, what other options do I have? I have looked up all the medications available for hypothyroid and they all seem to contain the same inactive ingredients. Getting pretty scared at this point. Dr. says to take antihistamines before taking the synthroid, but hives are still there and I can still feel the reaction going on. Don't know how much longer I can continue this. Please help!