Euthyrox (levothyroxine sodium) is L-thyroxine (T 4) indicated in pediatric and adult patients as replacement in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism; and as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer. Euthyrox is available in generic form.Administer a dose of Euthyrox once daily, on an empty stomach, one-half to one hour before breakfast. Administer Euthyrox at least 4 hours before or after drugs that are known to interfere with absorption.