Levothyroxine
Also called L-thyroxine.
The manufactured copy of the body's own thyroid hormone, taken when the thyroid does not make enough. Four iodine atoms make up nearly two thirds of its weight.
Sources and notes
- The introductionfrom sourceMoleculeFinder curated
- Other namesfrom sourceWikidataIts English label and aliases on Wikidata.
- Formula and weightcomputedPubChem
- 2D drawingcomputedPubChem structure, drawn by RDKit
- 3D modelfrom sourcePubChem 3D conformerLoaded after the page has painted, and on a phone only when you ask for it; the 2D drawing shows until it arrives.
Where you encounter it
Dispensed on prescription, not sold on a shelf. Levothyroxine on the product labels we hold.
Every product and list we hold
Sources and notes
- The product labels and their strengthsfrom sourceDailyMed (FDA label)Each label lists the molecule as an ingredient, and an active ingredient at the strength shown.
- How it gets therefrom sourceMoleculeFinder curatedEach mark is set by hand on our lists, never inferred; a label's ingredient is added by the maker. A row with no mark data says Not marked.
- The line abovefrom sourceMoleculeFinder curatedFrom the group the molecule belongs to.
Explore its structure
Choose a part to light it up.
A carbon carrying both a C=O and an O-H, written COOH. In water it gives up that hydrogen, which is what makes the molecule an acid.
From: standard chemistry.
An O-H fixed directly to a benzene ring. The ring makes that hydrogen easier to give up than an ordinary alcohol's, which is why many phenols act as antioxidants.
From: standard chemistry.
A nitrogen carrying one or two hydrogens. Its spare pair of electrons can pick up a hydrogen ion, so an amine is a base.
From: standard chemistry.
Sources and notes
- The drawingcomputedPubChem structure, drawn by RDKitThe page's one shipped drawing, with the chosen part lit in amber under it.
- The partscomputedFound by ruleEach part is found by a chemical pattern, never picked by hand atom by atom; its words say where they come from.
Properties and sources
Calculated by PubChem
- Molecular formula
- C15H11I4NO4
- Molecular weight
- 776.87 g/mol
- XLogP3octanol/water, log units
- 2.4
- Polar surface areatopological
- 92.8 Ų
- H-bond donors
- 3
- H-bond acceptors
- 5
- Rotatable bonds
- 5
- Complexity
- 420
Reported Hazard label (GHS), ECHA via PubChem
Danger Irritant pictogram (GHS07) and Health hazard pictogram (GHS08); hazard statements H302, H361, H372
Reported Licence
The US Food and Drug Administration licenses Levothyroxine for human use (NDA 021210, authorized August 21, 2000), as Unithroid. Drugs@FDA
Groups it belongs to
- Category
- Prescription medicine
- Family
- Hormone medicines
- Chemical groups
- Carboxylic Acids, Amines, Aromatics, Phenols, Ethers, Halogenated
- Hazard classes
- Irritant, Health hazard, GHS Danger
C1=C(C=C(C(=C1I)OC2=CC(=C(C(=C2)I)O)I)I)C[C@@H](C(=O)O)NPubChem CID 5819 · Wikidata Q773449 · InChIKey XUIIKFGFIJCVMT-LBPRGKRZSA-N · Data refreshed
Questions
- What is Levothyroxine?
- The manufactured copy of the body's own thyroid hormone, taken when the thyroid does not make enough. Four iodine atoms make up nearly two thirds of its weight.
- How toxic is Levothyroxine?
- Its GHS hazard label carries the signal word Danger and the hazard pictograms Irritant and Health hazard. from source
- What kind of molecule is Levothyroxine?
- Levothyroxine has the formula C15H11I4NO4 and a molecular weight of 776.87 g/mol. MoleculeFinder files it under hormone medicines, in the prescription medicine group. from sourcefrom sourcefrom sourcefrom source
- What else is Levothyroxine called?
- Levothyroxine is also called L-thyroxine. from source
- Who licenses Levothyroxine as a medicine?
- The US Food and Drug Administration licenses Levothyroxine for human use (NDA 021210, authorized August 21, 2000), as Unithroid. from source
Sources and notes
- Calculated valuescomputedPubChemComputed from the structure, so no laboratory conditions apply; complexity is PubChem's own structural score.
- Hazard labelfrom sourceECHA via PubChemThe label combines these classifications.
- ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
- Licencefrom sourceDrugs@FDARead 2026-10-21.
- Data refreshedfrom sourceMoleculeFinder2026-11-09
Keep exploring
More related molecules
- Phenylalanine Both carry a carboxylic acid and an amine group.
Sources and notes
- Similar in shapecomputedRDKit Morgan/TanimotoNeighbours by structural fingerprint; the sentence names the chemical groups the two share.
- The drawingscomputedPubChem structures, drawn by RDKit