Use this medicine only as directed by your doctor. Do not use more or less of it, and do not use it more often than your doctor ordered. Your doctor has prescribed the exact amount your body needs and if you take different amounts, you may experience symptoms of an overactive or underactive thyroid. Take it at the same time each day to make sure it always has the same effect.

If your condition is due to a lack of thyroid hormone, you may have to take this medicine for the rest of your life. It is very important that you do not stop taking this medicine without first checking with your doctor.

Dosing

The dose of these medicines will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets that you take depends on the strength of the medicine. The amount of thyroid hormone that you need to take every day depends on the results of your thyroid tests. However, treatment is usually started with lower doses that are increased a little at a time until you are taking the full amount. This helps prevent side effects.

For levothyroxine
• For oral dosage form (tablets):
  • For replacing the thyroid hormone:
    • Adults and teenagers At first, 0.0125 to 0.05 milligrams (mg) once a day. Then, your doctor may increase your dose a little at a time to 0.075 to 0.125 mg a day. The dose is usually no higher than 0.15 mg once a day.
    • Children less than 6 months of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.025 to 0.05 mg once a day.
    • Children 6 months to 12 months of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.05 to 0.075 mg once a day.
    • Children 1 to 5 years of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.075 to 0.1 mg once a day.
    • Children 6 to 10 years of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.1 to 0.15 mg once a day.
    • Children over 10 years of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.15 to 0.2 mg once a day.
• For injection dosage form:
  • For replacing the thyroid hormone:
    • Adults and teenagers 50 to 100 micrograms (mcg) injected into a muscle or into a vein once a day. People with very serious conditions caused by too little thyroid hormone may need higher doses.
    • Children less than 6 months of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.019 to 0.038 mg once a day.
    • Children 6 months to 12 months of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.038 to 0.056 mg once a day.
    • Children 1 to 5 years of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.056 to 0.075 mg once a day.
    • Children 6 to 10 years of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.075 to 0.113 mg once a day.
    • Children over 10 years of age The dose is based on body weight and must be determined by your doctor. The usual dose is 0.113 to 0.15 mg once a day.

For liothyronine sodium
• For oral dosage form (tablets):
  • For replacing the thyroid hormone:
    • Adults and teenagers At first, 25 micrograms (mcg) a day. Some patients with very serious conditions caused by too little thyroid hormone may need to take only 2.5 to 5 mcg a day at first. Also, some patients with heart disease or the elderly may need lower doses at first. Then, your doctor may increase your dose a little at a time to up to 50 mcg a day if needed. Your doctor may want you to divide your dose into smaller amounts that are taken two or more times a day.
  • For treating a large thyroid gland (goiter):
    • Adults At first, 5 mcg a day. Some patients with heart disease or the elderly may need lower doses at first. Then, your doctor may increase your dose a little at a time to 50 to 100 mcg a day.
• For injection dosage form:
  • For replacing the thyroid hormone in very serious conditions (myxedema coma):
    • Adults At first, 10 to 50 mcg injected into a vein every four to twelve hours. Then, your doctor may want to adjust your dose depending on your condition.
    • Children Use and dose must be determined by your doctor.

For liotrix (levothyroxine and liothyronine combination)
• For oral dosage form (tablets):
  • For replacing the thyroid hormone:
    • Adults, teenagers, and children At first, 50 micrograms (mcg) of levothyroxine and 12.5 mcg of liothyronine once a day. Some people with very serious conditions caused by too little thyroid hormone may need only 12.5 mcg of levothyroxine and 3.1 mcg of liothyronine once a day. Also, some elderly patients may need lower doses at first. Then, your doctor may want to increase your dose a little at a time to up to 100 mcg of levothyroxine and 25 mcg of liothyronine.

For thyroglobulin
• For oral dosage form (tablets):
  • For replacing the thyroid hormone:
    • Adults, teenagers, and children At first, 32 milligrams (mg) a day. Some people with very serious conditions caused by too little thyroid hormone may need to take only 16 to 32 mg a day at first. Then, the doctor may want you to increase your dose a little at a time to 65 to 160 mg a day.

For thyroid
• For oral dosage form (tablets):
  • For replacing thyroid hormone:
    • Adults, teenagers, and children 60 milligrams (mg) a day. Some people with very serious conditions caused by too little thyroid hormone may need to take only 15 mg a day at first. Also, some elderly patients may need lower doses at first. Then, your doctor may want you to increase your dose a little at a time to 60 to 120 mg a day.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses. If you miss 2 or more doses in a row or if you have any questions about this, check with your doctor.

Storage

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For thyroid hormones, the following should be considered:

Allergies Tell your doctor if you have ever had any unusual or allergic reaction to thyroid hormones. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy Use of proper amounts of thyroid hormone during pregnancy has not been shown to cause birth defects or other problems. However, your doctor may want you to change your dose while you are pregnant. This will make regular visits to your doctor important.

Breast-feeding Use of proper amounts of thyroid hormones by mothers has not been shown to cause problems in nursing babies.

Children Thyroid hormones have been tested in children and have not been shown to cause different side effects or problems in children than they do in adults.

Older adults This medicine has been tested and has not been shown to cause different side effects or problems in older people than it does in younger adults. However, a different dose may be needed in the elderly. Therefore, it is important to take the medicine only as directed by the doctor.

Other medicines Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking thyroid hormones, it is especially important that your health care professional know if you are taking any of the following:

• Amphetamines

• Anticoagulants (blood thinners)

• Appetite suppressants (diet pills)

• Cholestyramine (e.g., Questran)

• Colestipol (e.g., Colestid)

• Medicine for asthma or other breathing problems

• Medicine for colds, sinus problems, or hay fever or other allergies (including nose drops or sprays)

• Diabetes mellitus (sugar diabetes)

• Hardening of the arteries

• Heart disease

• High blood pressure

• Overactive thyroid (history of)

• Underactive adrenal gland

• Underactive pituitary gland