I have read several times of people who say they react badly to T4 and convert to only taking T3. I'd be most interested to know how they work that out. please let me know if you have had a bad response to T4. For the last two months I've been taking daily 10mcgs of T3 in 4 split doses and 50mcgs of T4. I have had some improvement but am still far from well. How do people know they are reacting badly to T4? Is the only way to reduce the dose of T4 and increase the T3? I'm seeing my endocrinologist in a few days and want to know if I should suggest this as a way forward.