Precautions
It is very important that your doctor check the progress of you or your child at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it. Blood and urine tests will be needed to check for unwanted effects.
Levothyroxine should not be used for the treatment of obesity or for the purpose of losing weight. This medicine is not effective for weight reduction. If taken in large amounts, levothyroxine may cause serious unwanted effects.
Hypothyroidism can sometimes cause infertility in men and women. Levothyroxine should not be used for the treatment of infertility unless it is caused by hypothyroidism.
For patients with diabetes, it is very important that you keep track of your blood or urine sugar levels as instructed by your doctor. Check with your doctor right away if you notice any changes in your sugar levels.
If you think you have become pregnant while using this medicine, tell your doctor right away. You may need a larger dose of levothyroxine while you are pregnant.
Women who use this medicine for a long time may have some bone loss, which could lead to osteoporosis. Talk with your doctor if you have questions or concerns about this.
Call your doctor right away if you or your child start to have rapid or irregular heartbeats, chest pain, shortness of breath, leg cramps, headaches, nervousness, irritability, sleeplessness, tremors, a change in appetite, weight gain or loss, vomiting, diarrhea, excessive sweating, heat intolerance, a fever, changes in menstrual periods, hives, or a skin rash. These could be symptoms of too much medicine in your body.
Make sure any doctor or dentist who treats you knows that you or your child are using this medicine. You may need to stop using this medicine several days before having surgery or medical tests.
A temporary loss of hair may occur during the first few months of levothyroxine therapy. Ask your doctor about this if you have any concerns.

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