It is not clear what kind of hyperthyroidism
you have? Grave's disease? Toxic nodule? etc. That is very important in deciding treatment. The chances of cure with tablets are less if it has not improved in initial 18 months. In that case, we need to think in terms of a definitive cure. The choice depends on the type of disease. You may need to visit an endocrinologist
who will arrange for a nuclear scan and then will decide further treatment.