Thyroid UK
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Starting T3 with T4 ,, need some guidance

hi Guys ,

my Endo has finally given me T3 medication along with T4 medication.

at the moment I was taking 125 MCG and she has asked me to now reduce the T4 to 100 and start 5mcg T3 in the morning and 5 mcg in the afternoon.

I have the following questions

1- I take T4 at night as its easier for me as I take multivitamins in the morning.

2 - if I take T3 in the morning , can I take multivitamins afterwards if yes after how long.

3- I have been told to take t3 in the afternoon , how do I take this as I if I take multivitamins then how much time do I need to delay this to take another t3 dose.

Can I take T3 10MCg together and 100mcg in the evening before sleep

and also whats is the dosage ratio between T4 and T3

as if I take 125 , how do I ratio accordingly ?

do I really have to take T3 on empty stomach ?

I know there are loads of questions , but would love to know your thoughts and guidance

3 Replies

Hi Mzahid,

All thyroid medication needs to be taken on an empty stomach otherwise it binds to food and drink and less is absorbed. Leave 2 hours between T3 and supplements. 4 hours if the supplements are calcium, iron or vitamin D.

T3 is 3 x stronger than Levothyroxine so it is usual to reduce Levothyroxine by 25mcg for every 10mcg T3 added.

Try the morning and afternoon dosing your endo recommended but if it doesn't suit you can either take 10mcg in one morning dose or added to 100mcg at night. Some people find taking T3 late in the day disrupts sleep but others find they sleep better if they take T3 at night. It's a bit suck it and see to find what suits you personally.


thanks clutter , whats the half life of T3 , if i take this in the evening before sleep , do you think i will feel the benefits in the morning ?


Mzahid, it's about 3 days. It takes 36/48 hours to get into the cells from the blood and will be out of your system 24/36 hours later. You might notice increased heart rate/pulse an hour or two after taking a dose but it usually returns to normal within an hour or so. You're not going to take a tablet at bedtime and wake up full of the delights of spring. Improvement is gradual and builds over a few weeks although brain fog and clarity of thought can improve within a few days.


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