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Thyroid UK
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Block and Replace - weight management


I have been diagnosed with Graves' disease in November. My endo has put me on 40mg of carbimasol with a view to starting levathyroxin next week - blood test dependant.

I'm just wondering about weight gain? I have put on 2Kg's since starting carbimasol 5 weeks ago.

Also what dose of levathyroxin are people on and how long does it take to work?



4 Replies

Not something I know about first hand and I'm sure you will get lots of replies but concentrate on getting stable and then I think your weight issue may settle down.


I didn't put on any weight on Carbimizole but I've as told that you can't take it long term as it causes Osteopenia (bone thining) which I already have in my spine due to undectected thyroid problems. I have been taken off of it, I was on a very low dose only 5mg. Have now had radioiodine treatment 5 weeks ago. Due to have blood test next week and to see consultant just after Christmas to work out the way forward. Might be worth checking the side effects out.


I took 20mcg a day for four weeks then had it increased (my surgery record shares with the hospital and I got a letter from my endo telling me what to do) to 40mcg a day for the next two months.

Make sure you have regular blood tests, two months on 40 without a blood test was too much fir me because I was hypo by the time I got to hospital to see my endo. I started on 50mcg levothyroxine along with the 40mcg carbimazole and gradually increased until I was taking 75/100mcg a day, still with the 40mcg carbimazole. When my bloods were where my doctors wanted them I stopped everything at once - Thursday 40carb and 100 levothyroxine - Friday nothing at all!

I started the carbimazole on 30th November 2012 , added in levothyroxine on 28th February 2013 - continued on both and saw my endo in April and July then again on 7th November 2013 when I stopped everything to see what happened.

I didn't put on much weight to begin with but read in Understanding Your Thyroid by Dr Anthony Toft that 'everyone does' and I though 'no I won't!' But I did, I don't know why that happens really but I went back to my starting weight which was a bit annoying really.

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I've been on carbimazole for over 6 years. I put on a bit of weight initially, but had lost 2 1/2 stone due to the Graves' disease. My weight has stablised and I don't really have a big problem. I do run and exercise regularly and feel extremely well.

I started on 40mg carbimazole and 50mg thyroxine.

Gradually been changed over the years and currently take 10mg carbimazole and 100 mg thyroxine. Been on this dose for about a year and levels haven't changed a great deal.

For me the block and replace is working well and I will keep on it for as long as I can.

Hope all goes well for you.

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