Thyroid UK
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Started T3/T4 combo


I started a combo of T4 (50mcg) and T3 (20mcg split into two 10mcg doses) a few days ago on prescription as I wasn't getting on with just T4, I was on 100mcg.

I've not felt great, feel a bit hit by a bus and quite nauseous. I'm taking my first dose around 6am with the levo then the second around 1pm on an empty stomach.

Is this a high dose? Should I have started lower?

8 Replies

If you were already taking T4/T3 it's not a high dose. You have to give it time for your body to settle and I'd wait at least six weeks. Your combined dose is about 90mcg of levo.

Also if you take your 1 p.m. dose your stomach has to be empty before, and after. If you've eaten a meal about noon you might have to leave about 2.5 hours before taking T3. Our digestion is also slow.


First time on T3, I have used NDT briefly.

Hmm so I'm actually on a lower dose overall on the combo than I was on just levo?


T3 is the only active thyroid hormone, T4 is inactive and it's job is to convert to T3. Maybe it doesn't always if people have problems with T4. This is from an expert who himself took 150mcg of T3 daily as he was thyroid hormone resistant. His recommendation was once daily dosing. I think it's easier to reach an optimum as your body reacts to too much and you reduce back:-

I am not medically qualified and it's my own experiences I have gone by. :)


Hi Shaws

I thought T3 was three times stronger than T4 so if that is the case then msislissa would be taking equivalent of 110 mcg. levo. Or have I got it wrong.


20mcg of UK T3 is thought to be around 60 mcg (in in its 'effect'). 25mcg levo approx 75 - 100mcg levo.

This is an excerpt from a link 80 Page just for info and is taken from page 80:-

Journal of Orthomolecular Medicine Vol 28, No 2, 2013

Dose Selection in T3/T4 Study RCTs. The second logical basis for a conclusion is the actions taken, i.e., the doses given to the

subjects. Most subjects received T3 below its adult starting dose of 25 mcg/day.

The subjects in RCTs received T3 in some ratio to the withdrawn T4. The various RCTs used T4:T3 ratios of 14:1, 10:1, and 5:1. Subsequent re-

search by the US National Institutes of Health (NIH) found the therapeutic equivalence was 3:1.

Thus, most of the subjects were under treated with the T3/T4 combination. In light of the NIH finding, the conclusion that T3

therapy is never needed is invalid

1 like

You might find it better to spread your T3 doses out further? I take my first dose early am on waking, then a later dose either before my dinner in evening (around 4pm) or later just before bed.


Ok so maybe my second dose is a bit early in the day?


Yes maybe. You could try taking it late pm or before bed and see if it helps reduce the nausea etc.


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