Why does CAS 61-73-4 appear in more than one EU cosmetic annex?

A substance identified by CAS 61-73-4 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts — for example, restricted under Annex III with specific conditions, while also appearing in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

How do I check if my formula contains a substance with CAS 61-73-4?

Use the INCI Checker on CosIng Checker with INCI names, CAS numbers or EC numbers. Paste CAS 61-73-4 to screen it directly, then review every linked annex record and supplier document.

CAS 1 record

CAS 61-73-4

Q: How do I use CAS 61-73-4 for compliance screening?

Cross-reference CAS 61-73-4 against your raw material specification sheets and CoA documents. When it appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met. All annex entries sharing this CAS number are listed on this page.

CAS 61-73-4 matches 1 EU annex record across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 61-73-4

CAS 61-73-4PubChem CID 6099

Methylene Blue

Methylene blue is an organic chloride salt having 3,7-bis(dimethylamino)phenothiazin-5-ium as the counterion. A commonly used dye that also exhibits antioxidant, antimalarial, antidepressant and cardioprotective properties. It has a role as an antioxidant, an antimicrobial agent, a physical tracer, an antidepressant, an EC 3.1.1.8 (cholinesterase) inhibitor, an antimalarial, an EC 1.4.3.4 (monoamine oxidase) inhibitor, an acid-base indicator, a fluorochrome, a neuroprotective agent, a histological dye, a cardioprotective agent and an EC 4.6.1.2 (guanylate cyclase) inhibitor. It contains a 3,7-bis(dimethylamino)phenothiazin-5-ium. — ChEBI

IUPAC name: [7-(dimethylamino)phenothiazin-3-ylidene]-dimethylazanium chloride

Molecular formula: C16H18ClN3S
Molecular weight: 319.9 g/mol
Exact mass: 319.0909965 Da
Topological polar surface area: 43.9 Å²
Hydrogen-bond donors: 0
Hydrogen-bond acceptors: 4
Covalent units: 2
Defined stereocentres: 0

Also known as

Basic blue 9Methylthioninium chlorideSolvent blue 8Swiss BlueC.I. Basic Blue 9ChromosmonMethylene Blue anhydrousMethylene Blue N

16 more reported names

Methylene Blue BBUrolene blueMethylenium ceruleumMethylthionine chlorideMethylene Blue chlorideBleu de methyleneMethylene Blue AMethylene Blue BMethylene Blue DMethylene Blue GExternal Blue 1Tetramethylene BlueCalcozine Blue ZFMethylene Blue BDMethylene Blue BPMethylene Blue BX

Open full PubChem record PubChem annotations 3D structure image

External database identifiers

ChEBI:CHEBI:6872
ChEMBL:CHEMBL405110
EPA DTXSID:DTXSID0023296
PubMed:35435491
PubMed:33844597
PubMed:33352258
PubMed:31428839
PubMed:31173149
PubMed:30907955
PubMed:30590764
PubMed:25943564
PubMed:24556215
PubMed:23769903
PubMed:23159732
PubMed:21554916

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Records for CAS 61-73-4

1 total

Annex

Entry

1306

Phenothiazin-5-ium, 3,7-bis(dimethylamino)- and its salts, when used as a substance in hair dye products

200-515-2

How CAS 61-73-4 is used on this site

CAS 61-73-4 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 1 EU annex record shares this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

Use this page when a supplier specification, SDS or raw-material dossier gives you CAS 61-73-4 and you need to see every linked Annex II–VI record in one place. The entry cards above are the quickest route to concentration limits, warnings, annex placement and product-type conditions.

Frequently asked questions

A substance identified by CAS 61-73-4 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts. For example, a substance might be restricted under Annex III with specific conditions, and the same CAS might also appear in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

Cross-reference the CAS number against your raw material specification sheets and CoA documents. When a CAS appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met in your formulation. All annex entries sharing this CAS number are listed above.

A CAS number is assigned by the Chemical Abstracts Service (USA) and is globally recognised. An EC number is a European Commission identifier from inventories such as EINECS, ELINCS or the NLP list. Both identifiers may appear in EU cosmetic annex entries. Some substances have both, some have only one, and some older entries may have neither.

The INCI Checker accepts ingredient names, CAS numbers and EC numbers. Check this CAS number directly, then verify the result against supplier specification sheets and every linked annex condition.

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