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Thyroid UK
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T3 dosage

Good morning. I now have my private prescription for T3 and this morning have had my bloods done. My GP suggested staying on the 125 of Levo and 1 x 20mcg tablet of T3 so that if there’s any problems it will be down to the T3. However l have read on this site that you should reduce Levo and start with a lower dose of T3. I take my Levo when l go to bed so advise on when to take the T3 would also be appreciated. Thanks in advanceto all of you wonderful helpful people.

8 Replies


We'd need to see your TSH, FT4 and FT3 results and ranges to advise whether, or how much, to reduce Levothyroxine.

That's very poor advice from your GP. 20mcg T3 is equivalent to 60mcg Levothyroxine so unless you are very undermedicated your Levothyroxine dose will need reducing.

You can divide the 20mcg into 2 x 10mcg doses and take 10mcg at bedtime with Levothyroxine and the second 10mcg dose in the morning.

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I will post the new blood results when l get them at the end of the week.

I thought the instructions he gave me were wrong. Apparently they only have one other patient taking T3 and it’s been a bit hit and miss. At least he gave me the private prescription.

Do l have to take it on an empty stomach? I will find it hard to not have a coffee when l get up.



Yes, take it away from food and drink as you would Levothyroxine.

Have your coffee and take 10mcg T3 dose 2 hours after.


Yes I’ll do thanks.


Personally I would start on just 2 x 5mcg

You can cut T3 into 1/4s with a small art scalpel

I actually started on 2 x 1/8th tablet for first 4-5 days before increasing to 2 x 5mcg

Stayed at that dose for 6 weeks before retesting.

Suggest starting with day time doses morning and afternoon

If you find T3 makes you sleepy you can take one dose at bedtime

It depends on your blood test results wether you need to reduce T4 at same time.

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Thank you for this. I will post my results when l get them tomorrow or Friday . Thanks for your help.

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My Levo was increased to 125 a day at the beginning of this year. My blood results from Tuesday are

TSH. 1.4 (0.27 - 4.2 )

FT4. 21 (11 - 22 )

T3. 4.5 ( 3 - 7.3 )

Serum Thyroid Antibodies 15 KU/L

The first 3 are now going in the right direction.

I am waiting for my T3 to arrive. Please can someone now advise re dosage now the new blood results are back. All vitamins etc are good. Thanks Yvonne


Ranges added


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