Eltroxin Tab 100mg is a medicine used to treat hypothyroidism, a condition where the thyroid gland doesn't make enough thyroid hormone. Each tablet contains levothyroxine sodium, a synthetic version of the hormone that replaces what the thyroid gland isn't making. It's a small, white, round tablet that you can easily take once a day. This medicine can also help prevent thyroid cancer from coming back after surgery. Hypothyroidism can cause symptoms like feeling tired, gaining weight, having trouble going to the bathroom, and feeling sad. It's important to follow the doctor's instructions when using this medicine to manage hypothyroidism effectively.