Synthroid – instructions for use, description, reviews of patients and doctors, analogues

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Synthroid – a medicine belonging to the group of thyroid hormones, is intended for the treatment of diseases caused by a deficiency of the hormones produced by it.

Release form and composition is available in the form of tablets containing the active substance represented by sodium levothyroxine at a dose of 50 or 100 mcg. The medicine is sold in cardboard packs containing 1, 3, 5 or 10 packs, each of which can contain 10, 20 or 50 tablets.

Indications for use

According to the official instructions for Synthroid, the drug is used for:

  • Hypothyroid states;
  • Toxic diffuse goiter after the use of thyreostatic drugs and the formation of an euthyroid state (with combination or monotherapy);
  • Thyroid cancer after surgery to eliminate the threat of tumor recurrence;
  • Diffuse euthyroid goiter;
  • The prevention of relapse of nodular goiter after removal of part of the thyroid gland while maintaining its functions.

The medication is also used in the complex treatment of autoimmune thyroiditis, Graves disease and for conducting a test that determines the degree of functionality of the thyroid gland using Synthroid as a diagnostic drug.

During pregnancy and breastfeeding, medication with hypothyroidism is not recommended to be discontinued. In the II and III trimesters of pregnancy, dose adjustment is required due to the increasing need for thyroid hormones. The use of Synthroid during lactation and pregnancy should be carried out under medical supervision in compliance with the recommended doses. Also allowed the use of the drug for children and elderly patients according to the prescribed dosage regimen.


According to the instructions attached to Synthroid, its use is contraindicated in

  • Untreated thyrotoxicosis;
  • Hypersensitivity to levothyroxine sodium;
  • Acute myocardial infarction, acute myocarditis;
  • Uncompensated adrenal insufficiency before taking the drug;
  • Hereditary galactose intolerance, defective absorption of glucose and lactose.

Also, during pregnancy, the combined use of Synthroid with Santithyroid drugs is contraindicated, since it is possible to increase their dosage. This can trigger the development of hypothyroidism in the fetus due to the ability of antithyroid drugs to cross the placenta (unlike levothyroxine sodium).

With extreme caution, Synthroid therapy is prescribed against the background of:

  • Angina pectoris;
  • Atherosclerosis;
  • A history of myocardial infarction;
  • Diabetes mellitus;
  • Arterial hypertension;
  • Prolonged and severely occurring hypothyroidism;
  • Arrhythmias;
  • Malabsorption syndrome (dosage adjustment is likely).

Dosage and administration

According to the instructions of Synthroid, the drug is taken orally, once in the morning on an empty stomach or no later than half an hour before meals, washed down with water. For children under the age of three years, the prescribed dose of the drug, dissolved in water immediately before use, is recommended to be taken 30 minutes before the first feeding. The daily dosage and duration of the course is prescribed by the doctor individually and depends on the indications.

In the course of replacement therapy for hypothyroidism for adults, the recommended dose of Synthroid per day is 1.6-1.8 μg / kg body weight for patients under 55 years of age and without cardiovascular system dysfunction (CCC), the initial dosage is equal to 75-100 mcg per day.

At the age of patients older than 55 years old or patients with CCC lesions, a daily dosage of 0.9 μg / kg body weight is prescribed, the initial dosage is 25 μg, with a further increase within 1.5-2 months to the full dose. With a congenital form of hypothyroidism, children up to six months are recommended to use Synthroid per day at a dosage of 8-10 μg / kg body weight. For children from 6 months to a year, a dose of 6-8 mcg / kg is prescribed per day, from 1 year to 5 years – 5-6 mcg / kg, for ages 6 to 12 years old – 4-5 mcg / kg, adolescents over 12 years – 2-3 mcg / kg.

Side effects

According to patients, the use of Synthroid with correctly prescribed doses of the drug and the control of a doctor is rarely accompanied by undesirable effects. In some cases, with intolerance to the drug, an allergic reaction can occur – itching and redness of the skin, skin rash. If too high doses of Synthroid are used, it is possible to develop: changes in heart rate, tachycardia, anxiety, insomnia, weight loss, tremor, diarrhea, excessive sweating, increased appetite, alopecia, and impaired renal activity in children. When observing these symptoms, the doctor may reduce the daily dosage of Synthroid or discontinue the use of the medication for several days, prescribe intravenous administration of glucocorticosteroids or use of beta-blockers.

Special instructions

In the treatment with Synthroid, any other drugs containing iodine, if necessary, should be used only after consulting a doctor.

Prior to Synthroid therapy, the risk of hypothalamic or pituitary hypothyroidism should be excluded.

When prescribing this drug to elderly patients, the initial dosage should not be more than 50 mcg.


The analogues of Synthroid, produced with the same active substance as this drug, include Bagotirox, Levothyroxine, Eutirox. According to the mechanism of action and the similarity of the therapeutic effect exerted, the analogues of the drug are Yodokomb, Tireokomb, Yodtiroks, Tireotom, Novotiral.

Terms and conditions of storage

Shelf life of Synthroid is 36 months, subject to the storage rules specified in the official instructions – a dry, cool (temperature below 25 ° C) place, away from light sources.

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