Generic Name: levothyroxine (LEE voe thye ROX een)
Brand Names: Euthyrox
Medically reviewed by Drugs.com. Last updated on Sep 26, 2018.
What is Euthyrox?
Euthyrox (levothyroxine) is a replacement for a hormone normally produced by your thyroid gland to regulate the body's energy and metabolism. Levothyroxine is given when the thyroid does not produce enough of this hormone on its own.
Euthyrox treats hypothyroidism (low thyroid hormone).
Euthyrox is also used to treat or prevent goiter (enlarged thyroid gland), which can be caused by hormone imbalances, radiation treatment, surgery, or cancer.
You may not be able to take Euthyrox if you have certain medical conditions. Tell your doctor if you have an untreated or uncontrolled adrenal gland disorder, a thyroid disorder called thyrotoxicosis, or if you have any recent or current symptoms of a heart attack.
Before taking this medicine
Euthyrox should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of levothyroxine, especially if you are taking any other weight-loss medications or appetite suppressants.
Since thyroid hormone occurs naturally in the body, almost anyone can take levothyroxine. However, you may not be able to take Euthyrox if you have certain medical conditions. Tell your doctor if you have:
an untreated or uncontrolled adrenal gland disorder;
a thyroid disorder called thyrotoxicosis; or
symptoms of a heart attack (chest pain or heavy feeling, pain spreading to the jaw or shoulder, nausea, sweating, general ill feeling).
To make sure Euthyrox is safe for you, tell your doctor if you have ever had:
a thyroid nodule;
heart disease, a blood clot, or a blood-clotting disorder;
diabetes (insulin or oral diabetes medication doses may need to be changed when you start taking Euthyrox);
anemia (lack of red blood cells);
osteoporosis, or low bone mineral density;
problems with your pituitary gland; or
any food or drug allergies.
If you become pregnant while taking Euthyrox, do not stop taking the medicine without your doctor's advice. Having low thyroid hormone levels during pregnancy could harm both mother and baby. Your dose needs may be different during pregnancy.
Tell your doctor if you are breast-feeding. Your dose needs may be different while you are nursing.
Do not give Euthyrox to a child without medical advice. Tirosint is not approved for use by anyone younger than 6 years old.
How should I take Euthyrox?
Take Euthyrox exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.
Euthyrox works best if you take it on an empty stomach, at least 30 minutes before breakfast. Follow your doctor's dosing instructions and try to take the medicine at the same time each day.
Swallow the tablet whole, with a full glass (8 ounces) of water. The tablet may dissolve very quickly and could swell in your throat.
Levothyroxine doses are based on weight in children. Your dose needs may change if you gain or lose weight.
It may take several weeks before your body starts to respond to levothyroxine. Keep using Euthyrox even if you feel well. You may need to use Euthyrox for the rest of your life.
You may need frequent medical tests. Tell any doctor, dentist, or surgeon who treats you that you are using levothyroxine.
Store at room temperature away from moisture and heat.
Do not share Euthyrox with another person, even if they have the same symptoms you have.
Euthyrox dosing information
Usual Adult Dose of Euthyrox for Hypothyroidism:
-HYPOTHYROIDISM IN ADULTS AND IN CHILDREN IN WHOM GROWTH AND PUBERTY ARE COMPLETE:
Therapy may begin at full replacement doses in otherwise healthy individuals less than 50 years old and in those older than 50 years who have been recently treated for hyperthyroidism or who have been hypothyroid for only a short time (such as a few months):
Average full replacement dose: 1.7 mcg/kg/day (e.g., 100 to 125 mcg/day for a 70 kg adult) orally
Older patients may require less than 1 mcg/kg/day
Doses greater than 200 mcg/day orally are seldom required
An inadequate response to oral daily doses of 300 mcg/day or greater is rare and may indicate poor compliance, malabsorption, and/or drug interactions
-FOR MOST PATIENTS OLDER THAN 50 YEARS OR FOR PATIENTS UNDER 50 YEARS OF AGE WITH UNDERLYING CARDIAC DISEASE:
-Initial dose: 25 to 50 mcg/day, with gradual increments in dose at 6 to 8 week intervals, as needed
-PATIENTS WITH SEVERE HYPOTHYROIDISM:
-Initial dose: 12.5 to 50 mcg orally once a day; dosage can be increased in 12.5 to 25 mcg/day increments every 2 to 4 weeks (accompanied by clinical and laboratory assessment, until the TSH level is normalized)
-PATIENTS WITH SECONDARY (PITUITARY) OR TERTIARY (HYPOTHALAMIC) HYPOTHYROIDISM: The oral dose should be titrated until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range.
Usual Adult Dose of Euthyrox for Myxedema Coma:
Myxedema coma is a life-threatening emergency characterized by poor circulation and hypometabolism, and may result in unpredictable absorption of the oral dosage form of this drug from the GI. Only the IV dosage form should be used for this condition:
-Initial loading dose: 300 to 500 mcg IV
-Maintenance dose: 50 and 100 mcg IV, until the patient can tolerate oral therapy.
Usual Geriatric Dose of Euthyrox for Hypothyroidism:
ELDERLY PATIENTS WITH CARDIAC DISEASE:
-Initial dose: 12.5 to 25 mcg orally per day, with gradual dose increments at 4 to 6 week intervals
-The dose is generally adjusted in 12.5 to 25 mcg increments until the patient with primary hypothyroidism is clinically euthyroid and the serum TSH has normalized.
Usual Pediatric Dose of Euthyrox for Hypothyroidism:
CONGENITAL OR ACQUIRED HYPOTHYROIDISM:
-Neonatal: 10 to 15 mcg/kg/day; if patient is at risk for development of cardiac failure, begin with a lower dose. In severe cases of hypothyroidism (T4 less than 5 mcg/dL), a higher initial dose of 12 to 17 mcg/kg/day may be considered.
-Age 0 to 3 months: 10 to 15 mcg/kg orally once per day; if the infant is at risk for development of cardiac failure use a lower starting dose of approximately 25 mcg per day; if the initial serum T4 is very low (less than 5 mcg/dL) begin treatment at a higher dosage of approximately 50 mcg per day
-Age 3 to 6 months: 8 to 10 mcg/kg/day
-Age 6 to 12 months: 6 to 8 mcg/kg/day
-Age 1 to 5 years: 5 to 6 mcg/kg/day
-Age 6 to 12 years: 4 to 5 mcg/kg/day
-Age 12 years and older: 2 to 3 mcg/kg/day
-Patients in which growth and puberty are complete: 1.7 mcg/kg/day
For chronic or severe hypothyroidism: 25 mcg orally once per day and increase dosage as needed in increments of 25 mcg every 2 to 4 weeks until the desired effect is achieved.
What happens if I miss a dose?
Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include headache, leg cramps, tremors, feeling nervous or irritable, chest pain, shortness of breath, and fast or pounding heartbeats.
What should I avoid while taking Euthyrox?
Avoid the following food products, which can make your body absorb less levothyroxine: grapefruit juice, infant soy formula, soybean flour, cotton seed meal, walnuts, and high-fiber foods.
Euthyrox side effects
Get emergency medical help if you have signs of an allergic reaction to Euthyrox: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
irregular heart rate;
chest pain, feeling short breath;
fever, hot flashes, sweating;
feeling unusually cold;
weakness, tiredness, sleep problems (insomnia);
memory problems, feeling depressed or irritable;
headache, leg cramps, muscle aches;
feeling nervous or irritable;
dryness of your skin or hair, hair loss;
changes in your menstrual periods; or
Certain side effects may be more likely in older adults.
Common Euthyrox side effects may include:
headache, leg cramps;
tremors, nervousness, trouble sleeping;
skin rash, mild hair loss.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect Euthyrox?
Many other medicines can be affected by your thyroid hormone levels. Certain other medicines may also increase or decrease the effects of Euthyrox.
Certain medicines can make levothyroxine less effective if taken at the same time. If you use any of the following drugs, avoid taking them within 4 hours before or 4 hours after you take Euthyrox:
ferrous sulfate iron supplement;
Many drugs can interact with levothyroxine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Euthyrox only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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More about Euthyrox (levothyroxine)
- Side Effects
- During Pregnancy or Breastfeeding
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- Drug Interactions
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- Drug class: thyroid drugs