Hi, Based on the history given you seem to suffering from hypothyroidism ( underactive thrydoid ) for which your doctor has prescribed thyrofit. Since your thyroid can not produce enough thyroid hormones you have to take it as a replacement therapy for life long. It is not known to cause any harmful effects on prolonged use. Generally it is well tolerated by most of our patients. However, its common side effects increased heartbeats, palpitation, sweating, lack of sleep, weight loss, and tremors. These side effects can be prevented by adjusting the dose of thyrofit. So, continue taking thyrofit as prescribed by your doctor and get the thyroid function tests as requested by your doc. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr. Mohammed Taher Ali, General & Family Physician