After being on T4 (75 mcg currently) for 2 years and never feeling well, I have been to see a consultant recently who has agreed to me taking a small amount of T3 also for a 3 month trial. She wants to reduce the T4 to 25mcg and add 10mcg of T3. She explained that T3, because it is a more powerful thyroid hormone and short acting, can cause a sudden rise then fall in active thyroid hormone level within the blood. She said the rise may cause anxiety, palpitations and flushing and the fall can cause profound fatigue before the next dose. I haven't yet started this combination so wanted to find out if anyone has experienced these reactions.