How long after you begin medication for your thyroid do you feel better?

Hypothyroid?: If you have hypothyroidism and you begin brand name T4 replacement, you should start to feel better in 4-6 weeks, but it takes 6 weeks for the rx to equilibrate in your body and then your doctor may have to readjust the dose at 6 week intervals. All in all, it can take up to several months for your body to fully recover back to normal.