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
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
- 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.