Also known as Synthroid, Levothyroxine is a thryroid hormone that is used when the thyroid gland does not produce enough hormone. They are also used to help decrease the size of enlarged thyroid glands (known as goiter) and to treat thyroid cancer
Be sure to tell your doctor of any allergies you have whether it is to medication or food, preservatives, or dyes. Also tell your doctor of any other medications you are taking, including vitamins and supplements, and any medical conditions you may have.
It is very important that you take this medicine exactly as your doctor tells you to. Do not take more or less medicine than directed, and don’t stop taking Synthroid unless you’ve discussed it with your doctor first.
If you miss a dose of this medicine, take it as soon as you remember, unless it is almost time for your next dose. Do NOT double doses.
Check with your doctor as soon as possible if any of the following (indications of an overdose or allergic reaction) occur: headache in children; skin rash or hives; chest pain; confusion; fast or irregular heartbeat; mood swings; muscle weakness; psychosis; restlessness; yellow eyes or skin; or shortness of breath.
Levothyroxine sodium tablets and injection contain synthetic crystalline L-3,3¢,5, 5¢-tetraiodothyronine sodium salt [levothyroxine (T4) sodium]. Synthetic T4 is identical to that produced in the human thyroid gland. Levothyroxine (T4) Sodium has an empirical formula of C15H10I4NNaO4xH2O, and molecular weight of 798.86 (anhydrous). Synthroid Tablets Inactive Ingredients: Acacia, confectioner's sugar (contains cornstarch), lactose, magnesium stearate, povidone, and talc. The following are the color additives by tablet strength: 25 mcg: FD&C yellow No. 6; 50 mcg: None; 75 mcg: FD&C red No. 40, FD&C blue No. 2; 88 mcg: FD&C blue No. 1, FD&C yellow No. 6, D&C yellow No. 10; 100 mcg: D&C yellow No.10, FD&C yellow No. 6; 112 mcg: D&C red No. 27 & 30; 125 mcg: FD&C yellow No. 6, FD&C red No. 40, FD&C blue No. 1; 150 mcg: FD&C blue No. 2; 175 mcg: FD&C blue No. 1, D&C red No. 27 & 30; 200 mcg: FD&C red No. 40; 300 mcg: D&C yellow No. 10, FD&C yellow No. 6, FD&C blue No. 1.
Synthroid Injection Inactive Ingredients: 10 mg mannitol, USP, sodium hydroxide, 0.7 mg tribasic sodium phosphate, anhydrous dodecahydrate. Levothyroxine sodium powder for reconstitution for injection is a sterile preparation.
Synthroid has the following structural formula: