Thyroid UK
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Meds stop working?

I recently increased my thyroid meds to 25T4/35T3 and for the first time in years I found I was able to sleep unaided and also poop naturally. Yeay!

But after working brilliantly for a couple of weeks, I have relapsed to insomnia and constipation.

Any ideas why this might happen? I realise there are probably scores of possible reasons but do any prime suspects leap to mind?

4 Replies

Hi - there can be a natural tail-off a few weeks after a dose increase and it is generally a sign that you are still under-medicated. Have you had any blood tests recently? I think it was greygoose explained it recently - when you put more hormone into your system, some of the receptors that have been turned off due to lack of supply wake up. However, when they find that there isn't enough to go round and fill them all, they then go "off in a huff" and close down again - someone else likened it to a supply of cake - lol!

I am still increasing dose to reach optimum and I have now got to the stage where I recognise that another increase is due and I suspect you re at that stage.

Gillian xx


That's very interesting, thank you Gillian.

I did wonder myself if I was still under-medicated. But when I try, for instance, 25/40 or even 12.5/40 I start to feel ratty, which always suggests to me I'm starting to be over-medicated.

I haven't had a very recent test no, but my last results (October) were certainly less than satisfactory, e.g. FT3 4.0 [3.1-6.8]. I've been waiting to feel stable on a particular dose for 6 weeks to get another test done, but keep failing to find the 'sweet spot'.

Guess it's a continuous trial and error situation.

1 like

Maybe you need to check your nutrients -vit D, ferritin, folate & B12? Could it be that you need to increase T4 rather than T3? Also how long after dose increase do you start to feel ratty? Maybe you need to persevere for a bit longer to allow an increased dose to settle.

A full blood test should give a better indication of whether you need to increase or not.


All nutrients listed checked and OK.

Actually now realise I might be getting a cold - hence ratty! Vitals are all OK.

Yes, will have to do another test soon but need to let dose settle in for a bit yet.


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