Is your dr giving you a choice on that surgery?
I once read (not sure how true it is) that there are no known allergies to levothyroxine. The only problems come from either the fillers or the drug’s interaction with other drugs. Levothyroxine is the placement therapy most prescribed to patients who’ve had their thyroids removed.
If you are concerned, then you will definitely want to go over all this with your dr. Perhaps he/she can do testing up front.
The only information I‘ve ever come across that touches on long term use has said that if you are treated properly and have good medical care you will be okay.
If you do come across a study, please share it. I’d love to read more.
Take care.
There are a lot of meds to choose from. So finding one that agrees with you shouldn't be a problem. The most hypoallergenic thyroid med is Thyrolar, which is a combo med of T3 and T4. Most people do not have allergies to thyroid meds....in fact any allergy is due to a filler in the med.