levothyroxine sodium, Synthroid, Levoxyl, Levothroid, Unithroid, Tirosint, Levo-T (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

SIDE EFFECTS: Levothyroxine therapy usually is well-tolerated. If symptoms occur, they often are due to toxic levels of thyroid hormone, and the symptoms are those of hyperthyroidism.

The most commonly reported side effects include:

GENERIC AVAILABLE: Yes. Generic and branded tablets of levothyroxine may differ:

  • in the amount of levothyroxine they contain,
  • the absorption of the levothyroxine into the body, and
  • the distribution of levothyroxine throughout the body.

This means that ingestion of 1 mg of generic levothyroxine may not have the same effect on the body as 1 mg of another generic or branded levothyroxine. Practically speaking, this means that when changing between levothyroxine manufactured by different pharmaceutical companies, a change in dose may be necessary to maintain the desired effect or to prevent toxicity. When switching between brands or generics, it is important to ensure that both preparations are equivalent or to check blood thyroid levels weekly.



  • Tablets: 0.025, 0.05, 0.075, 0.088, 0.1, 0.112, 0.125, 0.137, 0.15, 0.175, 0.2 and 0.3 mg.
  • Capsules: 0.013, 0.025, 0.05, 0.075, 0.088, 0.1, 0.125 and 0.15 mg.
  • Powder for intravenous injection: 200 mcg and 500 mcg per vial.

STORAGE: Levothyroxine tablets, capsules, and dry powder should be kept at room temperature, 15 C to 30 C (59 F to 86 F) in a light-resistant, tight container.

Powdered levothyroxine for intravenous injection should be used immediately once mixed with liquid.

Medically Reviewed by a Doctor on 12/11/2014

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