In my mid-70s, I was diagnosed with Graves disease in April and put on 20mg Carbimazole daily. This made me feel so ill that after a week I unilaterally put it down to 10mg. Saw Endo in June and he said I should increase to 15mg daily. After 3 weeks on 15mg I started running a high temperature at nights. Stopped the Carbimazole, went to A&E where they said my white blood cell count was down, so stayed off the pills. After a couple of weeks I became hyper-hyper - raging insomnia (though bags of energy by day - managed to get loads done!). GP said I should go back onto Carbimazole and gradually build up. So I started on 5mg a day (no effect) then put it up to 10mg.
At the same time I decided to address the underlying auto-immune condition and excluded all dairy and all gluten from my diet - inconvenient but not impossible. After a couple of months I was feeling fine, and at my October appointment the Endo said that all is back to normal and that I am now euthyroid! He then said I should continue to take Carb 10mg a day for the time being. However since it seems to have done its job (and since - in my case - there has been a history of over-prescribing this very potent medication) I have unilaterally put it down to 7.5mg a day, and still feel fine - indeed I'm now wondering whether to reduce to 5mg or whether to wait for my next blood test in January to see how things are.
I think the reason that the medication has been so effective is the other things I've been doing to treat the underlying auto-immune cause of the thyroid problem (i.e. the exclusion diet and also acupuncture once every 2 weeks). I'm posting this in the hope that this approach will work for others (I found out about it from Susan Blum's book "The Immune System Recovery Plan", which I therefore strongly recommend).
Very best wishes and best of luck to everyone, whether hyper- or hypo, and fingers crossed that we can all become, and remain, very well indeed.