Methylene blue
Also called methylthioninium chloride, methylenium ceruleum, Swiss blue and Ehrlich's reagent III.
A deep blue thiazine dye that doubles as a medicine for methemoglobinemia. It stains cells for the microscope, treats fish tanks, and turns urine green.
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
Where you encounter it
Dispensed on prescription, not sold on a shelf.
Sources and notes
- The line abovefrom sourceMoleculeFinder curatedFrom the group the molecule belongs to.
Explore its structure
Choose a part to light it up.
Rings joined where they share atoms, or a single ring standing alone. Atoms in a ring are held in place, so this part keeps its shape while chains around it can bend.
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
- C16H18ClN3S
- Molecular weight
- 319.9 g/mol
- Polar surface areatopological
- 43.9 Ų
- H-bond donors
- 0
- H-bond acceptors
- 4
- Rotatable bonds
- 1
- Complexity
- 483
Measured LD50, HSDB via PubChem
3,500 mg/kg pure methylene blue, mouse, oral
An LD50 is an animal study measurement, not a dose for a person.
Reported Hazard label (GHS), ECHA via PubChem
Danger Corrosive pictogram (GHS05) and Irritant pictogram (GHS07); hazard statements H302, H318, H412
Reported Licence
The US Food and Drug Administration licenses Methylene blue for human use (NDA 204630, authorized April 8, 2016), as Provayblue. Drugs@FDA
Groups it belongs to
- Category
- Prescription medicine
- Chemical groups
- Aromatics, Halogenated
- Hazard classes
- Corrosive, Irritant, GHS Danger
CN(C)C1=CC2=C(C=C1)N=C3C=CC(=[N+](C)C)C=C3S2.[Cl-]PubChem CID 6099 · Wikidata Q422134 · InChIKey CXKWCBBOMKCUKX-UHFFFAOYSA-M · Data refreshed
Questions
- What is Methylene blue?
- A deep blue thiazine dye that doubles as a medicine for methemoglobinemia. It stains cells for the microscope, treats fish tanks, and turns urine green.
- How toxic is Methylene blue?
- The reported LD50 of Methylene blue is 3,500 mg/kg (mouse, oral). An LD50 is an animal study measurement, not a dose for a person. Its GHS hazard label carries the signal word Danger and the hazard pictograms Corrosive and Irritant. from sourcefrom source
- What kind of molecule is Methylene blue?
- Methylene blue has the formula C16H18ClN3S and a molecular weight of 319.9 g/mol. MoleculeFinder files it in the prescription medicine group. from sourcefrom sourcefrom source
- What else is Methylene blue called?
- Methylene blue is also called methylthioninium chloride, methylenium ceruleum, Swiss blue and Ehrlich's reagent III. from source
- Who licenses Methylene blue as a medicine?
- The US Food and Drug Administration licenses Methylene blue for human use (NDA 204630, authorized April 8, 2016), as Provayblue. from source
Sources and notes
- Calculated valuescomputedPubChemComputed from the structure, so no laboratory conditions apply; complexity is PubChem's own structural score.
- LD50from sourceHSDB via PubChemOther values the sources report: mouse, intravenous, 77 mg/kg; mouse, another route, 150 mg/kg; rat, intravenous, 1,250 mg/kg. The page shows the one LD50 the site uses everywhere.
- 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