Cosmetic ingredient dictionary
Cysteine in cosmetics: what it is and what it does
Cysteine is a cosmetic ingredient that stops the product reacting with oxygen and going off. Open Beauty Facts finds it in 5 products, most often hair care.
By Bravoora teamUpdated Sources checked 2 sourcesHow we check
What does Cysteine do in a product?
In a cosmetic product, Cysteine stops the product reacting with oxygen and going off, makes hair easier to comb, softer or shinier, and hides an unwanted smell or taste. The EU’s CosIng database lists these jobs for it: antioxidant, hair conditioning, masking, antistatic, hair waving or straightening and reducing.
What other names and numbers does Cysteine have?
- CAS number
- 52-90-4, 3374-22-9
- EC number
- 200-158-2, 222-160-2
- CosIng reference
- 75422
Which products contain Cysteine?
Open Beauty Facts finds Cysteine in the ingredient lists of 5 of the 22,021 products it has a list for, most often hair care, hair masks and face masks.
Products with it, by country of sale: Singapore 3 · United States 2.
Counted on 13 October 2026 from Open Beauty Facts, which volunteers fill from real packs: it shows where Cysteine turns up, not how much of the market it is.
Bravoora reads this ingredient for everyone you shop for: an allergy or intolerance, a vegan or vegetarian diet, a calorie or protein goal, and the labels on supplements and skincare too. Build a profile · For dermatologists, dietitians and doctors
Sources
The job, the description and the EU annex entry are CosIng’s; the fragrance allergens are the EU Annex III names Bravoora’s label checker reads; the product counts are Open Beauty Facts’.
- European Commission: CosIng cosmetic ingredient database (functions, description, EU annex entry)
- Open Beauty Facts: product database, 77,506 products, read 13 October 2026, ODbL
Contains information from Open Beauty Facts, which is made available here under the Open Database License (ODbL). Read the licence · Download this dictionary’s data · How we check
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