Thyroid UK
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Adverse reaction to t3 increase

Hi All! I'm lucky and live in the US and have a nurse practitioner that prescribes both t3 and t4. She recently did blood work (see below), and increased both my t3 and t4 medicine. I've been able to tolerance the t4, however, not the 5mcg of t3. I added the additional t3 in the early afternoon, but it made my muscles in my legs hurt and burn and my face and neck hot/flushed (which in return made me a little anxious). I don't have this reaction to my morning t3!? I'm currently taking 62.5 mcg Synthroid and only 5 mcg liothyronine. I stopped taking the additional t3 in the afternoon after the second day of the increase because of the way it made me feel both days.

Results taken on 10-31-16

DHEAs- 147 35-430

TSH- 3.61 .358-3.74

T3 Free- 2.8. 2.2-4.0

T4 Free- 1.17 0.76-1.46

Anti-TPO-695.0. 0-35

Anti-TgAB-45. ND-40

TBG-14. 14-31

I'm currently taking D3 with K, magnesium, B12, fish oil and a probiotics. Both D3 and B12 were low on a test a while back. I'm unsure of ferritin and am planning on asking to have that tested.

7 Replies


Have you tried taking 10mcg T3 with your Levothyroxine 62.5mcg? If you can't tolerate the T3 increase ask for Levothyroxine dose to be increased to raise FT4 and FT3. 5mcg T3 is equivalent to 15mcg Levothyroxine.

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Hi Clutter! Do you mean have I took the additional 5 mcg liothyronine in the morning? If so, then no I haven't. I thought the two doses needed to be split. So I've always been on the 5 mcg, but added the other 5 in the afternoon.



You've established that taking a second 5mcg dose in the afternoon doesn't suit so it may be worth trying whether 10mcg in the morning is okay. Some people take their entire T3 dose as one daily dose.


I have never split doses of whatever combination of thyroid hormones I've taken. First our stomachs have to be completely empty as food interferes with the uptake and also we cannot judge the 'effect' a certain dose has if we split.

I take my one daily dose of T3, just under 50mcg, as soon as I get up and am fortunately it has worked superbly for me. I wait an hour before having breakfast.

I don't know how long you've been taking thyroid hormones but your TSH is too high - should aim for 1 or lower. Both FT4 and FT3 are too low and should be towards the upper part of the range.

This is an extract re T3:

Now, to address your rheumatologist’s assertion that T3 is dangerous, and his implication that amitriptyline is not. I think the best way to reply to him is to quote publications that are available to him. In the USA, when patients get their prescriptions filled for T3 (usually the brand Cytomel), the pharmacist usually gives them a leaflet on the product. The leaflet contains the following statement:

"NO COMMON SIDE EFFECTS HAVE BEEN REPORTED with the proper use of this medicine." (Medi-Span, Inc.: Database Version 97.2. Data © 1997.)

This statement makes a fact perfectly clear: When used sensibly, T3 is extraordinarily safe among prescribed drugs. When I say extraordinarily safe, I’m comparing T3 with drugs such as the amitriptyline which your rheumatologist prescribes for you.


Thank you both so much for your replies! I will definitely try my t3 all at once in the morning.


Did you happen to take a Vitamin B before you had the burning/ flushed reaction, because it sounds like the reaction one gets after taking a bit too much vitamin B3, niacin.


I wish that wee the case, but no, it was the t3.

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