does irregular use of Synthroid cause serious health problems?

from what i know...it could, i take it, and I have been taking it my whole life, i know that if i dont take it after a couple of days, i feel alot worse than if i dont..

I agree with nicolewo8's response. I am assuming your daughter doesn't struggle with fatigue from being hypothyroid, because she feels she doesn't need to take it every day. For many of us, we know exactly how we will feel if we miss a day or two, and it's horrible (at least for me). It depends on your daughter's symptoms really. If Synthroid isn't taken faithfully everyday, then the symptoms won't go away, and will only get worse as time goes by. -Karly