How long before thyroid drugs out system? - Thyroid UK

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How long before thyroid drugs out system?


Just wondering how long before thyroid drugs are totally out system after stopping them?

And how long before you could have a blood test after stopping them and the result would show what your body was making naturally on its own ie. the thyroid drugs that you had been taking won't make a difference to the result anymore

Thank you

6 Replies


If you are taking Levothyroxine 4 weeks should be long enough for most to have left your system but there may be traces left for up to 8 weeks after last dose.

If you are taking Liothyronine you can halve the above.


I would think between six to eight weeks. If you stopped though, you might feel quite ill.

If your body needs thyroid hormones you may feel quite unwell without any for six weeks.

briskate in reply to shaws

Thank you for your quick responses.

I was on a trial of nature-throid but I stopped it after 7 weeks because of this hurrendous feeling it gave me. It made me feel so much worse.

(My blood tests were within range - it was just a trial to see if it helped my chronic fatigue)

So now it's 4 weeks I've been off them & I'm still bedbound with this same hurrendous feeling I got when I started them. Very scared it's done something permanent to me or maybe I just need a few weeks longer as like I mentioned it's only been 4 weeks since I stopped them.

Maybe until the hormone levels stop falling and level out it makes you feel bad. Do you think this could be the case?

Thank you very much.

Clutter in reply to briskate


32.5mg NatureThroid is a very low dose and is unlikely to have raised thyroid levels significantly. There really isn't likely to be any left in your system after 4 weeks. Taking NatureThroid won't have caused damage, temporary or permanent.

Not sure why I'm still feeling the same unwell feeling then.

Thanks for your reply anyway :)

Can you tell us more back ground and then we may be able to help more?

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