After starting out on levo 18 yrs ago and having allergic reaction within 9 months, went on to Armour and was ok for years. Then couldn't get it as doctors would no longer subscribe. Went onto several others and none worked (underactive thyroid) and, finally, on Thyroid S became balanced again over the last 3 years. However, I am now getting very sore eyes (often the precurser to an allergic reaction and I'm allergic to loads of things unfortunately). I also have to take NAX. I have slightly reduced the Thyroid S and the NAX and, though the symptons are still there, they have decreased. Does anyone have any info on prolongued use of Thyroid S or NAX come to that? Thanks in advance.