Hi, this is Soaplvr4evr answering Barb135. I have used Synthroid since 2006 (almost 19 years) due to my thyroids being removed for papillary thyroid cancer. Synthroid has only T4 in it, by the way. I need to stay hypothyroid all my life according to my doctor. I never had a problem with itchiness all over but mostly in my face, scalp, and ears. I do also have environmental allergies to some trees of which Acacia is high on the list. I never knew Acacia is in Synthroid. Now that I am older (65) I need to be careful not to take too high a dosage to prevent heart problems. I just recently started having itchiness just 22 minutes after Synthroid 137mcg (blue one), so my doctor switched me to compounded levothyroxine which has avicel in it (methylcellulose). I started the compounded one three days ago, but also am itchy on face, so I will call my doctor to switch the prescription to a compound pharmacy that's in-network with my insurance (only one such pharmacy is and it's in New Jersey), and they can use other fillers such as rice flour or tapioca starch for highly allergic people. If I get itchy from that too, then it probably is that I slowly developed an allergy to the levothyroxine. I will then try levoxyl which I understand is throxine (not levothyroxine??). Anyways, I will start off with the other compound pharmacy (with only T4 along with either tapioca powder, rice flour or potato starch which all three are natural fillers. Avicel and Loxoral are both synthetic fillers the compound pharmacy said they also put in levothyroxine capsules, according to whatever my doctor writes on the prescription. Thanks for your quickly replying to my post before!