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Antioxidant

Cystine

A sulfur-containing amino acid dimer essential to keratin structure, used in hair and skin formulations to support the strength and integrity of keratinized tissue.

StructuralConditioningStrengthening
✓ Safe
Comedogenic Rating
0/5
Irritation Potential
0/5

What is it?

A sulfur-containing amino acid formed from two cysteine molecules linked by a disulfide bond, naturally abundant in keratin-rich tissues like hair, skin, and nails, used in cosmetics primarily for hair and nail conditioning.

Supports the structural integrity of keratin-based tissues by supplying the sulfur-containing amino acid building blocks essential to disulfide bond formation, contributing to hair and nail strength.

Key Benefits

✦
Keratin Structure Support
Provides amino acid building blocks central to the disulfide bonds that give keratin its structural strength, relevant to hair and nail health.
◈
Hair Conditioning
Frequently used in hair care formulations to support the strength and resilience of hair fibers, particularly for damaged or chemically treated hair.
✧
Nail Strengthening Support
Included in some nail treatments for its role in supporting the keratin structure that comprises nail plates.

Suitable for

Damaged hairBrittle nailsAll skin types

Main Actions

✓ Structural support✓ Conditioning✓ Strengthening
Cystine vs Cysteine

Cystine and cysteine are easily confused but structurally distinct — cysteine is the single amino acid, while cystine is the dimer formed when two cysteine molecules bond together. Both play related but distinct roles in keratin structure and hair care formulations.

CategoryAntioxidants

Frequently Asked Questions

What does Cystine do for skin?
Supports the structural integrity of keratin-based tissues by supplying the sulfur-containing amino acid building blocks essential to disulfide bond formation, contributing to hair and nail strength.
Who should use Cystine?
Cystine is suitable for: Damaged hair, Brittle nails, All skin types.
Are there any warnings about Cystine?
Cystine and cysteine are easily confused but structurally distinct — cysteine is the single amino acid, while cystine is the dimer formed when two cysteine molecules bond together. Both play related but distinct roles in keratin structure and hair care formulations.

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