Is CYSTEINE safe to use in EU cosmetics?

CYSTEINE is listed in the EU CosIng ingredient inventory with no direct annex restriction records linked at this time. Always verify against the current official CosIng database before formulating.

What function does CYSTEINE serve in cosmetics?

According to the EU CosIng inventory, CYSTEINE carries the following function designation(s): ANTIOXIDANT, ANTISTATIC, FRAGRANCE, HAIR CONDITIONING, HAIR WAVING OR STRAIGHTENING, REDUCING.

InventoryRef 7542215/10/2010

CYSTEINE

Q: How do I check if my formula contains CYSTEINE?

Use the INCI Checker tool on CosIng Checker to paste your full ingredient list and scan it against all EU annex records and allergen flags in one step.

L-Cysteine

CYSTEINE is listed in the EU CosIng inventory, but no direct annex records are linked on this page yet.

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Inventory details for CYSTEINE

INCI name

CYSTEINE

INN name

cysteine

Description

L-Cysteine

Annex records for CYSTEINE

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Key data

CAS

52-90-4 / 3374-22-9

200-158-2 / 222-160-2

Restriction

—

Function

ANTIOXIDANT ANTISTATIC FRAGRANCE HAIR CONDITIONING HAIR WAVING OR STRAIGHTENING REDUCING

How CYSTEINE appears in the CosIng inventory

The CosIng inventory lists CYSTEINE as a cosmetic ingredient and this page links it to 0 annex records. The inventory entry captures names and identifiers, while the annex records show where the substance is prohibited, restricted or positively listed in EU cosmetics law.

CYSTEINE is also tagged with 6 cosmetic functions in the official data. Function labels describe intended use, but they do not replace regulatory review of linked annex records before formulation or labelling work.

Frequently asked questions

CYSTEINE is listed in the EU CosIng ingredient inventory with no direct annex restriction records linked at this time. Absence of an annex link does not guarantee unrestricted use — always verify against the current official CosIng database before formulating.

According to the EU CosIng inventory, CYSTEINE carries the following function designation(s):

CAS 52-90-4 / 3374-22-9 may appear across multiple EU annex records. Viewing the CAS lookup page shows all Annex II–VI entries sharing this identifier, which is useful for identifying cross-annex regulatory status of the same chemical substance.

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Use the INCI Checker tool to paste your full ingredient list and scan it against all EU annex records and allergen flags in one step.

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Source note for CYSTEINE

This page reproduces the CosIng inventory entry for CYSTEINE from public European Commission cosmetic ingredient materials and shows linked identifiers even when no direct annex match is currently attached.

Use this inventory page to research CYSTEINE and compare linked records, but verify restrictions and legal status against the current official source text and law before making regulatory decisions.

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Tools & next steps

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Scan a full INCI list to detect CYSTEINE and any linked EU annex restrictions or allergen flags.

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