Thyroid UK
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Has anyone had an adverse reaction to T3/Liothyronine?

I was put on this drug last week and within 18 hours was hit with immense fatigue, by the weekend I had to stop taking it and revert to Thyroxine only again (literally thought I was going to pass out at one point). Am still recovering now, feel like I've been drugged with sleeping pills. Any similar experiences please?

11 Replies

Hi Cario

I have looked on your profile but it gives no thyroid gland history. Are you hypothyroid. Were you on levothyroxine previously? If so, what dose of levo and what dose of T3 did you take?

You wouldn't have an adverse reaction to liothyronine itself but maybe to the fillers/binders in it.


Hi Shaw, I've only just signed up today so trying to learn what I'm supposed to be doing! I've now filled in the "bio" on my profile, so please have a look - hopefully it will give a bit more background. I've been on 100mcg/125mcg thyroxine alternating days over the past year. Previously was on 125mcg daily. The Endo did blood tests and my Free T3 came back at 3, just below the bottom of the normal range. Also ferritin levels low (13). Last week he put me on 20mcg liothyronine with thyroxine reduced down to 25mcg daily. When I reacted badly he suggested increasing the thyroxine to 50mcg and if that didn't work to come off the T3 completely and revert to original dose of thyroxine only.

Thanks for replying.



Hi Caroline,

Somebody more knowledgeable will be along to advise on your Free T3 which is too low, as is your Ferritin - it should be up at 70 minimum, preferably 90.


I hope Clutter sees above as she had Graves and is also very good with bloods.

Many people forget to put their history but it is good if we have a little background info.

I think the problem may not be the T3 it may be due to your very, very low ferritin level. Some excerpts followed by links to read the whole article:-

1. Why do we often have low iron levels? Because being hypothyroid can result in a lowered production of stomach acid which in turn leads to the malabsorption of iron, whether revealed with low ferritin, or with inadequate levels of serum or saturation. It can also lower your body temperature (common for those on T4-only thyroxine, as well) which causes you to make less red blood cells. Some even find themselves with a higher-than-normal temperature with on-going iron problems.

2. In turn, having low iron levels decreases deiodinase activity, i.e. it slows down the conversion of T4 to T3. Biologically, insufficient iron levels may be affecting the first two of three steps of thyroid hormone synthesis by reducing the activity of the enzyme “thyroid peroxidase”, which is dependent on iron. Thyroid peroxidase brings about the chemical reactions of adding iodine to tyrosine (amino acid), which then produces T4 and T3. Insufficient iron levels alter and reduces the conversion of T4 to T3, besides binding T3. Additionally, low iron levels can increase circulating concentrations of TSH (thyroid stimulating hormone).

3. What is ferritin? Ferritin is an iron-storage protein which keeps your iron in a dissolvable and usable state, making the iron non-toxic to cells around it. So when Ferritin is measured via a blood test, it is basically measuring the iron you have tucked away for safe use. 70 – 90 is often mentioned in literature as a goal, but other iron labs are important with it, as your ferritin can look good, but your other labs reveal the truth. Inflammation tends to thrust iron into storage, so you can’t just look at Ferritin.

I have read that for us hypos we need a ferritin level of around 90 so yours is nearly extinct. Reading the above, with low ferritin your T4 cannot convert to sufficient T3 and then you can get reverse T3.

So it looks as if you may have another iagtronic illness. (i.e. caused by doctors). Go to GP and ask for medication to increase your iron/ferritin. Then we can go forward from there.

When you put blood test results always put the ranges (figures in brackets) as labs differ throughout the country.

When you go for your next blood test for the thyroid gland, get it as early as possible and do not take your medication until afterwards. Also ask for Vitamin B12, Vitamin D, he will do iron, ferritin and folate too as we are usually deficient in all of these which can cause problems in themselves.

Also do not eat for about 1 hour after taking your medication as some foods can interfere with the uptake. Supplements or other medication should be taken 4 hours apart from thyroid medications.


Thank you so much for all your effort and help. The ferritin range on the blood test was 5-148 but the Endo refused to even consider this or looking further into my adrenal system. His stance was "why go looking for things" and "not to do too many tests at once". I have just started taking Floradix anyway as I realise there is a big problem with my ferritin. I researched and read that is is much better absorbed than tablets, but I still don't know if it will be adequate. After reading your reply I have requested a phone call from my GP so I will discuss with him. I still am not clear why introducing T3 with low Ferritin would make me feel like I was on my last legs as I assumed it must be an adrenal gland issue. I am considering making an appointment to see Dr Barry Peatfield but it will be a big expense and now so many of you lovely people are giving me advice I wonder whether to wait. Do you have a view on that?



So you are actually on a reduced dose of hormones - no wonder you feel awful. You needed T3 probably on top of your levo. You are now on the equivalent of about 85mcg of levo. of course you feel tired as you are on about half the previous dose. You also need ferritin at around 70.


Thanks for that. I questioned the Endo over this dosage and he said it was equivalent to 125mcg of thyroxine. I did think it seemed very drastic. And he refused to consider my low ferritin levels either. All in all he has proved an absolute disaster.


I have serious problems with many prescription drugs and have suffered like you.

I thought you may find the following helpful.

The following article was written twenty years ago:- Excipients, adverse drug reactions and patients' rights.

NPS MedicineWise is one of my favorite websites. I have included the following links for easy use.

 Hormonal and metabolic system Endocrine and metabolic disorders

 Liothyronine sodium

 Tertroxin Tablets

 Other ingredients in medicines

 The best website for advice on any prescription is drug


Many thanks for all that useful information. It is proving to be a great help being on this forum, I can't believe my luck!


Cario, I think your T4 was reduced too much and the T3 was insufficient to make up the difference. I'd advise taking your normal T4 dose and add 10mcg of T3 for a few days to see how you tolerate it and then increase it to 20mcg. You can take the 10mcg T3 with your T4 dose. When you increase to 20mcg you can take it all with your T4 or split the dose and take the second 10mcg 4/8 hours later. It's suck it and see to work out whether single or split dosing suit you best.


I did question him over the dosage but he said it gave me the equivalent of 125mcg of thyroxine. Also he refused to address my low ferritin levels, insisting we try one thing at a time. Thanks very much for your suggestion, I feel very lucky to have the help of people like you on this forum.


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