Thyroid UK

T3 supplementation

I've been prescribed T3 by my Endo take take alongside my Levo, as as feeling awful, had a TT over 17 years ago.. She reduced Levo from 142.2 to 100, T3 prescribed 10mcg twice per day. Been on it since Thursday 10th August. Since Tuesday morning 1 hour after taking the first tablet I've had strange palpitations, skipping a beat every 10. Other than that the change is fantastic, I feel wonderful. So this morning I took a 5mcg dose instead of 10, effectively halving it. Strange palms have gone. I'm wondering if this is because Levo will still be height whilst adapting to T3. Thinking of leaving it a couple of weeks then increasing dose. If I go back to Endo she will undoubtedly take me off it and Ive had to struggle to be listened to. She did say she does not understand much about it but willing for me to do the research. She also said she's had a few patients who've gone on to T3 and didn't like the palpitations so just came off.

I'm so not willing to give up without a fighting chance as I feel so good otherwise and had a fight to get this far! Any input would be welcome!

6 Replies


It's not uncommon to feel pulse/heart increase within an hour or so of taking T3. They should subside to normal within another hour or so. If the palpitations are too uncomfortable after taking 2 x 10mcg try splitting your dose into 4 x 5mcg. As you become used to T3 you may be able to comfortably resume 2 x 10mcg in a few weeks.


Many thanks for that, just as I was hoping!


Bless you, don't you love when they tell you they don't know anything about it except that people don't feel well on it? Erm, any connection there, maybe not prescribing it v well? Endo has given you the equivalent of something like an extra 60-100 levo while only reducing your actual levo by 42.2, so no wonder you feel a bit over.

Glad you're feeling better. It will take some time for your levo to reduce so yes, you may be a little bit overreplaced for now but you can reduce and try again in a week or so. Play around w it and see how you get on. If it makes you feel perky you can always try taking 10-20 in the morning and you may not need to split your dose once the extra levo is out of your system.

The split dose is v much a personal preference. I don't do it because my whole dose doesn't give me any trouble (eg palps) but what does give me trouble is remembering to take it twice a day.


Yes, it does feel like we're on our own at times! I think can now feel the Levo starting to dip as starting to feel that slight pull inside. May now be time to start to increase the T3 again. Will be getting private blood tests done as well to check if there are any other issues. X


Suggest you ask GP to check levels of vitamin d, b12, folate and ferratin. These all need to at good (not just average) levels for thyroid hormones (our own or replacement ones) to work in our cells.

Make sure you get the actual figures from tests (including ranges - figures in brackets). You are entitled to copies of your own results. Some surgeries make nominal charge for printing out.

Alternatively you can now ask for online access to your own medical records. Though not all surgeries can do this yet, or may not have blood test results available yet online.

When you get results suggest you make a new post on here and members can offer advice on any vitamin supplements needed

If you can not get GP to do these tests, then like many of us, you can get them done privately

Blue Horizon - Thyroid plus eleven tests all these.

This is an easy to do fingerprick test you do at home, post back and they email results to you couple of days later.

Usual advice on this test, (home one or on NHS) is to do early in morning, ideally before 9am. No food or drink beforehand (other than water) don't take Levo in 24 hours before (take straight after). This way your tests are always consistent, and it will show highest TSH, and as this is mainly all the medics decide dose on, best idea is to keep result as high as possible.

Best advice is to read as much as you can. Vitamin and minerals levels are very important, but standard NHS thinking, doesn't at the moment seem to recognise this. You will see, time and time again on here lots of information and advice about importance of good levels of B12, folate, ferritin and vitamin D

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Thank you for this. There is a great deal of great advice. One thing I must do is get my ducks in a row (STTM). GP won't do tests other than TSH and T4. Have ordered the Horizon kit but unfortunately got Thyroid +10. However it will be a good start. In Scotland, where I live, can't get online medical records....

Apologies for delay in replying, have been in Lakes without wifi!


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