Levothyroxine (Eltroxin) tablets are used to replace the Thyroxine hormone that your thyroid is not making.
They are taken every day, and usually lifelong.
The dose may need to be adjusted from time to time.
It is advised that you have your thyroid function (blood tests) checked once per year, once you are stable, or more often if you are concerned your symptoms are not well controlled or you are planning a pregnancy or are pregnant.
Your TSH level is what is used to assess if you are on the correct dose of medication.