Synthroid is hormonal drug used to diagnose, treat and prevent diseases of the thyroid gland.

Indications for use

Primary and secondary hypothyroidism (reduced thyroid function), a comprehensive treatment of grave’s disease (a disease characterized by a diffuse enlargement of the thyroid gland and increase in its function), euthyroid hyperplasia (abnormal enlargement) of the thyroid gland, prevention of recurrence (re-development) after surgical treatment of nodular and malignant neoplasms of the thyroid gland, cretinism (congenital deficiency of thyroid function, characterized by a sharp decrease in mental and physical development). The dose of 1 mg is used for differential diagnostic test of thyroid suppression (suppress thyroid function).

Drug contraindications

Absolute contraindications for the drug use for differential diagnostic test are acute myocardial infarction, acute myocarditis (inflammation of heart muscle), untreated Addison’s disease, severe arrhythmias, severe hyperthyroidism (a disease characterized by increased function of the thyroid gland). There are no absolute contradictions for performing a therapy (the injection of the substance /thyroxine/, a natural formation of which is reduced or terminated). Relative contraindications are severe forms of ischemic heart disease, general arteriosclerosis, severe hypertension (increased blood pressure), circulatory failure.

Method of application and dosage

Synthroid is taken orally, in the morning on an empty stomach (30 minutes before a meal), with small amount of liquid (1/2 cup of water). You shouldn’t chew the pill. The daily dose is determined individually on the basis of indications.

Side effects

If you use Synthroid properly, side effects will not develop. In the case of hypersensitivity to the drug components, you may experience allergic reactions.

Special instructions

In case of hypothyroidism caused by lesions of the pituitary gland, it should be clarified whether the disease is accompanied by failure of the adrenal cortex. In this case, in order to avoid acute adrenal insufficiency, the replacement therapy with glucocorticoids should begin prior to the therapy of hypothyroidism of thyroid hormone.


The overdose may cause worsening of coronary heart disease, diabetes, Addison’s disease (low adrenal function), rarely – violations of heart rhythm, diarrhea, vomiting, insomnia. On the first 2-3 days after administration of a diagnostic dose (3 mg), you may experience sweating, palpitations, weakness.

Treatment: appointment of beta-adrenoblockers, intravenous injection of corticosteroids, plasmapheresis.