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medications are of two types
One which inhibit the thyroid secretion and is given in people with high Thyroid hormone levels.
Other being Thyroid hormone substitute is given in people with low thyroid levels.
Please discuss with your treating doctor which type of medication is he asking you to take.This wold answer your doubt.
It is dagerous to take thyroid substitute when the thyroid level is high.
high and T3 T4 levels low indicate hypothyroid
Reverse indicate Hyper thyroid.
Hope I answered your query.