Levothyroxine - Synthroid, Levoxyl, Tirosint Thyroid Drugs

Levothyroxine, Synthroid, Levoxyl, Tirosint

levothyroxine, thyroid hormone replacement, hypothyroidism


L-Thyroxine, L-T4 Levothyroxine is an FDA-approved drug used to treat hypothyroidism -- an underactive thyroid -- and as thyroid hormone replacement in those who have surgically removed or a chemically ablated thyroid gland.

Levothyroxine is a synthetic drug form of the thyroid hormone known as thyroxine, abbreviated as T4. Levothyroxine is also known as l-thyroxine or l-T4.

Levothyroxine is the preferred thyroid hormone replacement drug for the endocrinologists and mainstream medical community, as well as the 2014 "Guidelines for the Treatment of Hypothyroidism" published by the American Thyroid Association's Task Force on Thyroid Hormone Replacement.

Levothyroxine is available as a generic drug from a variety of manufacturers, as well as a number of brand name makers. Generic levothyroxine is considered equivalent to brand names, but patients need to be careful to ensure that they get consistent dosing from refill to refill of levothyroxine.


According to FDA information, the following are the potential side effects of levothyroxine:

  • temporary hair loss
  • increased sensitivity
  • tiredness
  • diarrhea
  • tremors
  • headache
  • shortness of breath
  • increased sweating
  • nervousness
  • mood swings
  • insomnia

Note that to a large extent, when dosed properly, levothyroxine has few side effects. Side effects of levothyroxine are primarily associated with overmedication.


Some of the FDA's warnings regarding levothyroxine include the following:

  • Do not take with sympathomimetic drugs -- drugs used to treat cardiac arrest, low blood pressure, and delay premature labor, among other uses things.
  • Separate multivitamins with minerals -- calcium -- by at least three hours, to avoid reduction of the effectiveness of the levothyroxine.
  • Take at the same time, and in the same way (ideally without food) each day to ensure consistent absorption
  • The effectiveness of levothyroxine can be decreased if taken with soybean flour, cottonseed meal, walnuts, dietary fiber, calcium, and calcium-fortified juice and drinks
  • Patients should consult their physician before taking blood thinners while on levothyroxine



Manufacturer: Abbvie/ Abbott Laboratories
Drug Site: https://www.synthroid.com/
Patient Resources: http://www.synthroidpro.com/patient-resources/brochures.aspx
Consumer Hotline: (800) 227-5767 / 847 937-6100
RxList Listing: http://www.rxlist.com/synthroid-drug.htm
Notes: Synthroid contains lactose and acacia, which may be allergens in some patients


Manufacturer: Pfizer/King Pharmaceuticals
Drug Site: http://www.levoxyl.com/
Patient Resources: http://www.pfizerrxpathways.com/?step=1
Consumer Hotline:1-800-438-1985 / 1-800-TRY-FIRST
RxList Listing: http://www.rxlist.com/levoxyl-drug.htm


Manufacturer: Lannett Company
Drug Site: http://www.unithroid.com/
Patient Resources: http://patient.unithroid.com/
Consumer Hotline: (215) 333-9000 / (215) 333-9000
RxList Listing: http://www.rxlist.com/unithroid-drug.htm


Manufacturer: Akrimax Pharmaceuticals ​
Drug Site: http://www.tirosint.com/
Patient Resources: http://www.tirosint.com/
Consumer Hotline: (888) 383-1733 / (908) 372-0506
RxList Listing: http://www.rxlist.com/tirosint-drug.http://www.tirosint.com/patient-information/starthtm

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