Hi, Thyrox 100 tablet contains thyroxine which is used to treat an underactive thyroid gland or hypothyroidism. It replaces the hormone that isn t being produced by the thyroid gland in sufficient quantity and helps to regulate the body s energy and metabolism. When you take the proper dose of Thyrox, it is considered safe and has few side effects. If you take very high doses, you could experience very unpleasant and uncomfortable symptoms. Signs and symptoms of overmedication can vary, but some common ones include: elevated pulse and blood pressure, anxiety, tremors, feeling irritable, overemotional, erratic or depressed, difficulty in concentration, difficulty in sleeping or always feeling sleepy, tiredness, fatigue, flushed face, diarrhea, feeling overheated, feeling like the heart is skipping a beat or racing, increased food intake, anxious etc. The dosage of Thyrox that your doctor prescribes may be too high for you. This is why close monitoring is important, which means getting your TSH level checked within six weeks after a dose change and consult your doctor promptly. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician