Thyroid UK

Muscle cramps/pains/stiffness in calves and legs

I was diagnosed with an under active thyroid 3 weeks ago and was given 50 micrograms of Levothyroxine for the first 4 days until the GP said I had been given too low a dose and upped it to 100 micrograms of Levothyroxine daily. I am still getting really bad leg cramps and muscle soreness. I went back to the GP 2 days ago and have now given me muscle relaxants which have helped a little bit - is this just masking the problem? Why am I still getting the pains?

My TSH level was 17.88 ('normal' range 0.27-4.20)

Free T4 was 6.

9 Replies

Hi, it takes 6weeks for levothyroxine to reach a steady level in the blood. So it may just be that you need to let things settle for a few more weeks yet.

Did you have the leg cramps and muscle soreness pre-diagnosis? Or is this just since beginning on thyroxine? Xx


Hi, I had the cramps before diagnosis. Hopefully they will settle in time, can't sleep with them 😟


You were overtly hypothyroid 3 weeks ago with a TSH of 17+, so you're probably feeling really poorly at the moment. Try to rest as much as possible :)

Usually when first started on levothyroxine, your GP will re-test your Thyroid Function again in 6-8weeks. It takes that long to reach a steady level in the blood. Then depending on that result you will be given 25mcg increases in dose until your TSH is around 1. That is the TSH that most hypothyroid people feel comfy with, despite some GPs being happy when it is merely in range :(

So always ask for the actual figures at your reviews and make a note of them, better still ask for a copy of your results.

Remember to take your levothyroxine on an empty stomach with water only. Wait an hour to eat/ drink afterwards. Take levothyroxine well away from iron-containing tabs/liquids, as your levothyroxine won't be absorbed properly.

It may take a year for you to feel recovered. You will have been unknowingly hypothyroid for a long time and it will take that length of time to recover. However, you should feel increasingly better every 6 weeks after an increase in dose.

By the way, there is a link between Hypothyroidism and low levels of Vitamin D, Low haemoglobin, low ferritin and low B12 levels. Has your GP tested all of these? Even if the results are in range, we hypothyroid patients need the results to be high in range, with supplementation if necessary, to feel well and for our thyroid medications to work properly.

Low levels Vit D, Haemoglobin, B12, ferritin levels can cause muscle aches and cramps; xx


Thank you for your comments. I have a copy of the last blood results and will ask for the next ones - appointment booked for 26th May.

You are right, I do feel quite poorly at the moment and am signed off work to try and rest :)

I did have my B12 and ferritin levels checked, B12 was in range but my ferritin was above the range.

Thank you for the advice and help. Have had more information on here today than I have had from my last 3 GP visits :( I know they are under pressure but it would be great he would just spend some time to explain it all.

I will wait in anticipation of the levels sorting themselves out. x


There is a little book "Understanding Thyroid Disorders" by Dr Toft -very informative. You can buy it in most pharmacies and is less than £5. Good starting point.

best of luck xx


Thanks, I will have a look for the book x


Hi, can i ask if you had this resolved? I am only slightly/borderline hypothyroid but because of infertility they have put me on 75mg levothyroxine. I have been on this for three weeks and in the last few days have been waking up with extreme calf muscle soreness- like I've been doing lunges too. Am concerned it means I've gone hyper - see

Thanks for your help, hope you feel better now

1 like


It maybe that you actually need magnesium. Our bodies need magnesium for 600 different functions and western diets are typically low in this essential mineral. There are a number of different forms that can be used, just a little bit of internet searching will provide details of the different types or the pharmacist could help. Good luck:)


Muscle cramps are better (but still there) - not sure if it was because I had a vitamin D deficiency and now got my levels up or that I have added T3.


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