Thyroid UK
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T3 Dosage advice

ok so I started taking T3 a few weeks back, I am on 100mcg of T4, have been monitoring my temperature and I'm now up to 75 a day of the T3, I have noticed my weight shifting a bit and there is a slight increase in temperature but I am still not at the correct temp (most days 35.5 ) Do I keep going up with the T3, is 100 or more a dangerously high dose, or should I be doing something else



17 Replies

I'm on 175mcg of T3 per day, no T4; I'm not dead yet. There are people on this site who take even more than this.

The thing to do is to keep a close eye on temps, pulse and bp, etc., and only increase slowly. If you overdo it just don't take any more until things return to normal. I've not heard of anyone expiring after taking a little too much once in a while.

You might like to follow Dr. P's protocol of keeping a diary with dosages, bp, pulse and temp. readings and comments on how you feel.


Paul, that's a lot of T3 in a few weeks. 75mcg T3 is equivalent to 225mcg T4. Most people start a lot lower and increase slowly. I would advise having a FT3 test from Blue Horizon or Genova via to check FT3 is not over range.


See thats exactly what i dont get, if im not converting t4 to t3 then those equations surely are not valid. Also if my temp is still low and i have no hyper symptoms why do i need a blood test? Im grateful for your reply but it vastly different from the previous reply. I did start low the first week 25 split in two and there was no difference. Then i moved up to 50 a slight change in temp, and even at 75 my temp is not normal level. I really cant afford to buy numerous blood tests each time i move up a dose.


One possibility (but there is lots of dispute about this, so be aware of that).

You might have high reverse T3 levels.

There are other websites that have very different opinions on the subject :


Interesting thank you had a quick read through and still dont fully understand rt3 .. But one observation he states on the brands page is that Tiromel the brand i have is weak. Like i said i have seen an increase in temp and a weight drop ( one of the reasons i recon t4 is not working my metabolism is stuffed and i cant loose any weight) interestingly i was on 200 t4 for years then over the last

year or so GP decreased it to 100. Last blood test free T4 was 13.8 (10 - 19.8) Tsh level 1.19 (0.35. - 5.5)


Paulnorri, forum replies usually give a variety of opinions. 12.5mcg isn't starting low and increasing to 50mcg in the second week and now 75mcg within a few weeks isn't increasing slowly. Like Levothyroxine it takes 6-8 weeks for a T3 dose to have full impact. If you weren't converting well on 100mcg T4 12.5mcg T3 would probably have been sufficient. The T4+T3 would work synergistically.

Monitoring temperature can be helpful but low temperature in long term hypothyroid patients doesn't always improve and isn'tshouldn't be the only guide to determine under or over medication.

You have increased your dose from 100mcg to the equivalent of 325mcg too quickly. A blood test is in order after dose adjustment up or down to check levels. This link explains dose adjustment on NDT but works the same for T4+T3.


Thats not what i have read about t3 the half life is much shorter than t4 most places i have read its out of your system within days unlike t4. Also i have read in numerous places that blood tests for free t3 can be misleading as you may or may not have taken a dose. Can i ask are you a doctor or is this from personal experience?


Even if it is out of your system, that doesn't mean that the effect of what you took some time ago doesn't continue for quite some time.

Thyroid hormone affects the rates of creation of various proteins. The presence of those proteins continues even when the thyroid hormone which switched on the process to create them has disappeared.

Looking only at blood T3 levels has its own interest and usefulness but it is far from the complete story.


Paulnorri, I'm not a doctor and am speaking from personal experience and research.

Members are advised to leave twenty four hours between last dose and blood draw to measure the circulating hormone rather than the peak levels caused by recent ingestion. T4's half life is around 7/8 days and T3's about half that. Levothyroxine and T3 can peak in the blood for up to 6 hours after ingestion although T3's half life makes it likely it will be out of the blood within 6 hours. It takes a further 36/48 hours for T3 to enter the cells from the blood and another 36/48 hours for the last dose to be out of your system.

75mcg T4 + 40mcg T3 made my FT3 8.4 (3.2-6.2) 24 hours after last dose. I felt well and didn't feel overmedicated but I had considerable hairloss and nail breaking for several weeks until levels dropped. 75mcg + 30mcg dropped FT3 back to 4.5 also 24 hours after last dose. I have been advised that when 24 hours is left between last T3 dose and blood draw FT3 can be extrapolated by +20% to get an accurate FT3 reading.


I'm sorry but I just had to reply again on this thread, I have been lucky enough to get a copy of Dr Lowe's book on "The Metabolic Treatment of fibromyalgia" in it, on page 964, when talking about treatment and switching from T4 or NDT to T3, he says it is perfectly ok to start on day 8 (after going one week without any T4 or T3) with a quarter of a 25mcg T3 tablet, raising it daily by a quarter tablet until you are on 75mcg on day 14. Obviously keeping an eye on signs of over stimulation as you go! :) Hope this helps!


I agree with you Paul, I can't afford all the different tests either and in the past I have found that the tests don't prove how I feel, I have been feeling terrible for years, and tried Levo and Armour (long story) but am now on T3 I am not out of the woods yet but am increasing my dosage according to Dr Lowe's protocol! I have just increased my dose to 100mcg and my bp went too high and pulse was too high, so I have dropped down to 93.75, my symptoms have improved but not enough for me but I think I need to get all the T4rT3 out of my system.


Hi thanks for the reply, i think mine maybe a rt3 problem as well, i have cut the t4 in half to 50 a day and reduced the t3 to 50 thats been for the last two weeks. Also taking 3 adrenal glandulars a day, i feel reasonably well but my temp is still low, thinking of upping the t3 to 75, how long does the rt3 take to right itself and should i stop the t4 altogether to help that?


Hi Paul, I am, like you experimenting, i could never tolerate Levo so was buying Armour for years, some of the symptoms improved but not all, then last year I had severe fibro symptoms and all hypo symptoms got worse, so having read loads of research I assumed my problem was the T4 part of the Armour so I decided to follow Dr Lowe protocol and try high dose T3 but completely stopped all other thyroid meds! I started six weeks ago and am now on 93.25 mcg! But I still have the fibro pain, my temp is better, still brain fog and really tired! But my nails are growing, constipation improved and I have lost weight, i will keep increasing dose until I feel better! In the beginning I increased dose quickly as I had no symptoms but now I have had to slow down! But I think the pain is getting better! I have been told on here that it could take up to 14 weeks for the excess T4 or rt3 to leave your body! i am on week 6 and hoping they are right! I have also been told that the dose of T3 might be too much when this happens so this is something to beware of! :)


Well i dont understand why nearly all the info i have read says to start on 12.5 split doses and work up monitoring temp and pulse rates and watching for hyper symptons .. Actually one of the leading docs a few years ago Dr Skinner put me straight on 50 and that was without a blood test ... My gp refuses to prescribe and i cant afford numerous blood tests, they are expensive ... So where does that leave me


I too am moving over to T3 however I was on 150 before and my endo droped me to 100 then add 10mcg in the morning and then 10 mcg in the afternoon. I did this for 3 months then got my bloods tested just to check I was still ok. Now I have reduced my levo again but this time I have changed to 35mcg of t3 25 mcg in the morning with my levo and the rest late on in the afternoon as I do not need it till then, I have been quite careful to take it slowly as I have noticed I feel much better. My temperature has been 36.4 constantly through out the last 4 months. Although before I got the t3 it was always under 36.

It is understandable that you want to feel well I too thought about just going straight onto what I thought was the right dose, T3 is very different to T4 however I have felt so ill for the past few years I decided if I was going to switch it was going to be slow and gradual, I want to do this right so that I can have the benefit for the future and I am putting some money aside each week so that in 6 months I can test myself again.

Surely without a doctor to advise you, it is better to take small steps, no one runs a marathon without doing some training first. Frustrating thought it is, and I am not a doctor and my doc does not want to prescibe either, it took a long time to get ill, you need time to get well too.

I dont think there is a quick fix give yourself some time and start to save for the tests without a doctor to advise you have to be careful, there is a lot of conflicting evidence out there.

I wish you luck


Ok i have decided to cut back to 25 and reduce my t4 by half to 50 .. If its a rt3 problem i think this will sort it, or maybe i should stop the t4 for a while. Im also going to get an adrenal stress test .. Any comments?


I have just bought the book recovering with T3, it does have some useful information in it about how to go only T3, but I am not sure that that is right for me at the moment it seems like it takes a lot of time to get the dose right, and as I work I am not sure that I can go down this road without loosing my job.

Another interesting thing is that going T3 only seems to make the testing more difficult to interpret which also makes going it alone without a gp or endo for advice more risky. I am still trying to decide how to move forward but am going to try spliting my dose 3 ways and see if that helps me.


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