How much T3 should I take?: Hello, I have... - Thyroid UK

Thyroid UK
101,655 members116,514 posts

How much T3 should I take?


I have finally received my T3 which I ordered online as cannot get where I live and would like some advice on dosage.

My most recent results are listed below and since I received the results I started taking 125 of Levo as it was indicated my results were quite low from some feedback I received on this site.

After seeing my Endo and explaining that I still felt tired etc she agreed I should try T3 and suggested a dosage of 25mcg.

Does anyone have any advice on dosage and do you think I should reduce my Levo to 100 or 75 if I am taking T3?

Here are the results:

T3 = 0.857 - (0.84 - 2.02)

RT3 = 0.21 - (0.10 - 0.35)

T3/RT3 = 4 (no range given)

T4 = 7.06 - (5.13 - 14.06)

TSH = 3.09 - (0.270 - 4.20)

B12 = 618.3 - (200 - 950)

Ferritin = 50.75 - (13 - 150)

Iron Serum = 56 - (37 - 145)

Many thanks in advance for any advice :)

7 Replies

It looks as though your are currently undermedicated generally. You would expect to see your TSH at or below 1 and your FT4 above half way in the range if you were adequately medicated on Levothyroxine. Many people find T3 takes a while to get used to and start on a low dose for a week or so and build up slowly. If it was me i would keep the Levothyroxine the same and start with half a pill a day of T3, see how you feel (take it in the morning), then if you don't feel over-cooked and are still sleeping OK you could try taking the full 25mcg. You will soon know how it works for you. If you feel undercooked on 12.5mcg but overcooked on 25mcg you cold think about reducing the Levothyroxine by 25mcg.

Someone else who has actually taken T3 should answer soon.

1 like

I have been taking 20 mcg T3 only for the last 8 years. I take 1 first thing in the morning, one about mid afternoon then one last thing before bed. My new GP has now refused to prescribe it so I have ordered it online. Problem being they are 25 mcg. I will have to see how the different dose affects me. Good luck.

1 like

Hello Witchymp - thanks for the reply - it helps give me and idea of what sort of dosage to take and when. I have ordered online and hoping that the tablets are ok - the supplier was recommended by private message from a few of the members on the site so am sure will be ok. Thanks again :)

1 like

Hi Eeng - thanks very much for the reply - thats very helpful and will give this a go and try to increase according to how I feel. Thanks again :)



I'm at the same stage of just starting T3 at a low dose. However I was advised to stop my T4 meds when I started my T3. My lab test showed a low level of conversion of T4 to T3 , so perhaps that is why. Is that correct, or should I be taking both together?


It depends on your blood test results. If you were not converting T4 to T3 then probably your FT4 was high (high in range or maybe over the top limit) and your FT3 was low (less than half way up the range). In that case taking less T4 is a good idea because high levels of FT4 floating round your body when you can't use it can make you feel ill.

If you look at Bristol1965's results you will see that the T3 and T4 results were less than half way up the range and the TSH is high at over 3 so more medication is likely to help.


I havent had FT4 and FT3 bloods done, just the 24 hour urine lab test and saliva teat for my adrenals. Im just waiting for TSH result from my GP but thats not going to tell me much.


You may also like...