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What is levothyroxine, and are there differences between the brand-name and generic versions?


Levothyroxine - a medication that contains naturally occurring thyroid hormone - is used to treat hypothyroidism, a condition in which the thyroid gland does not produce enough thyroid hormone. Levothyroxine does indeed have generics with a few differences from the brand name versions like Synthroid® and Levoxyl®. Without this hormone, the body cannot function properly, resulting in poor growth, slow speech, lack of energy, weight gain, hair loss, dry thick skin, and increased sensitivity to cold. When taken correctly, levothyroxine reverses these symptoms. It also can be used to treat congenital hypothyroidism (cretinism) and goiter (enlarged thyroid gland).

Here are some important facts about levothyroxine:

  • Generic levothyroxine contains the same active ingredient as brand-name Synthroid® and Levoxyl® but is available at a lower price than the brand-name drugs. The Food and Drug Administration (FDA) has determined that generic levothyroxine and brand-name Synthroid® and Levoxyl® are equivalent. The FDA requires all drugs - both brand-names and their generic counterparts - to be proven safe and effective. Since generics use the same active ingredients and are shown to work the same way in the body as their brand-name counterparts, they also have the same risks and benefits.
  • If you are considering asking your doctor about switching between a brand-name product and generic levothyroxine, be aware that while the FDA has deemed generic levothyroxine therapeutically equivalent to both Synthroid® and Levoxyl®, your doctor should determine if a switch is suitable for you.
  • Levothyroxine requires the same amount of monitoring as the brand-name products. However, your doctor may require one additional blood test eight to 12 weeks after starting generic levothyroxine. Your doctor will determine whether you will need to have additional blood tests.
  • Synthroid®, Levoxyl®, and generic levothyroxine have the same active ingredients, but they look different. In the United States, trademark laws do not allow a generic drug to look exactly like the brand-name drug. While the colors, flavors, and certain other inactive ingredients may be different, the active ingredient is identical.

Learn more about your thyroid medication.

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Answers to questions regarding information about medications or health conditions are not for diagnostic or treatment purposes and are not conclusive as to the presence or absence of any health condition. Consult your physician for diagnosis and treatment of your medical condition. The information provided is not a substitute for medical advice. Advances in medicine may cause this information to become outdated, invalid or subject to debate. Professional opinions and interpretations of the scientific literature may vary. Walgreens' terms of use and general warranty disclaimer apply to all services provided. If you are in need of immediate medical attention, contact your physician, poison control center or emergency medical professional. If you need to speak with a pharmacist for non-emergency matters, contact your local Walgreens pharmacist or call a pharmacist toll-free at 1 (877) 250-5823.

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