Thyroid UK
82,821 members97,845 posts

T3 only

I have now been on T3 for three weeks taking 12.5 daily, I feel so much better on it but would like to come of my T4. Has anybody got any advice on that, my new blood results are..

TSH 0.03 (0.35-5.5)

Free T4 13.6 (9-24)

Total T3 2.1 (0.9-2.8)

My endo after reading these results told me to cut down levothyroxine from 75 to 50mcg unfortunately my pharmacist says he can't get teva lactose free levo in 50mcg tablets. I would rather just take T3 but a little apprehensive. any advice would be really appreciated.


4 Replies


3 weeks isn't long enough for FT3 to respond to the 12.5mcg T3 dose. FT3 is likely to be still rising. FT4 is low in range so I can only assume your endo wanted you to reduce Levothyroxine in order to raise your TSH.

It would be much better to wait until you have been taking T4+T3 for a couple of months and see how you feel then as well as checking TSH, FT4 and FT3 to see whether you are optimally medicated before switching to T3 only. I find T4+T3 is a smoother ride than T3 only.

However, if you are determined, 75mcg Levothyroxine is equivalent to 25mcg T3 so you would need to increase dose to 37.5mcg and retest in 6-8 weeks to check FT3 level.


I was on T3 only and it helped a lot at first, but it tanked my ft4 levels which did not agree with my system. I started getting severe muscle pain and stiffness. I have to have my ft4 in range to feel well. I wouldn't stop the t4. It's necessary, especially if you are only taking a lower dose of t3. Your body will still need some ft4 to convert to ft3 when your med isn't doing the trick. But if you are not able to convert ft4 to ft3, then that's an entire other story.


Thank you abd I agree with you . So good to have help and support from this site.

Thanks again and stay well x


I am on T3 only but was on levo & T3 for 6 months before I made the decision with my Endo in July to remove the 50mcg of levo I was taking. Btw I was on levo only for 12 months and was really poorly and bloods showed I wasn't converting so I introduced T3 in January this year.

Based on my bloods I wasn't converting and levo wasn't of any benefit to me. But everyone is different so I agree with Clutter give T3 time to get into your system and get your levels right then review what your taking and how your responding :)

1 like

You may also like...