Cysteine: Properties, Uses, and Contraindications

Cysteine: Properties, Uses, and Contraindications

Cysteine is a non-essential amino acid that is highly useful and versatile in the cosmetics world, known for its remarkable properties in strengthening and protecting hair and nails. It can be extracted from animal hair or derived from plant sources through synthetic processes.

What It Is and What It’s Used For

Cysteine is an amino acid with a polar side chain, essential for protein synthesis. This element is fundamental for cell renewal, maintaining tissue elasticity, and strengthening protein fibers such as keratin. Thanks to its unique structure, cysteine forms bonds called disulfide bridges, which give hair strength, elasticity, and resilience.

Benefits

1. Strengthening
   Cysteine is a precursor to keratin, a key protein that improves hair’s robustness and elasticity. Through the formation of disulfide bridges, it contributes to fiber resilience, protecting them from breakage and damage. It acts like a sort of “glue” that binds the hair fibers together, making them stronger and less prone to breakage.

2. Antioxidant
   As a component of glutathione—one of the most powerful antioxidants—cysteine combats free radicals, reducing oxidative stress and countering environmental damage.

3. Protective
   It forms a protective barrier on the surface of hair and skin, helping to maintain natural hydration and defending against potentially harmful microorganisms, atmospheric agents, pollution, and chemical treatments.

4. Regenerating
   Indispensable for sensitive or irritated skin, cysteine is effective in cases of acne and dermatitis, promoting a more uniform and radiant appearance.

5. Elasticity and Resilience
   Cysteine helps retain moisture within the hair shaft and improve fiber density, making it softer, silkier, and more luminous.

What Is the Difference Between Cysteine and Cysteamine?

Origin and Structure

• Cysteine is an amino acid, while cysteamine is its simplified derivative.

Main Function

• Cysteine focuses on strengthening and protecting protein structures such as hair, skin, and nails.
• Cysteamine is used to break hair’s disulfide bonds or reduce skin hyperpigmentation.

Applications

• Cysteine is used in products to strengthen hair during eyelash and eyebrow lamination.
• Cysteamine is used in lamination products to open the hair cuticles.

In short, cysteine is ideal for structural support and hair reinforcement, while cysteamine is intended to “open” the hair.

Where It Is Found

Cysteine is widely used in the formulation of cosmetic products such as:

• Anti-aging and soothing creams
• Anti-acne lotions
• Pre-shampoo masks
• Balms and serums for eyelashes and eyebrows
• Hand and nail creams
• After-sun creams
• Eyelash and eyebrow lamination products (such as My Lamination’s Lami Powder)

Cysteine in Lamination

Cysteine stands out for its ability to modify the viscosity of cosmetic products, making lamination treatments more precise and personalized. It also improves the adhesion of lashes to the silicone pad, ensuring optimal application. This property should not be confused with any change to the My Lamination® lamination procedure or its processing times. The key point is to maintain a maximum 50/50% (1:1) ratio between the product and the powder. Specifically, cysteine is used to modify the density of Phase 1 or Phase 2 products, but they should not be mixed together because each phase has its own function: Phase 1 opens the hair cuticles, while Phase 2 neutralizes Phase 1.

During the lamination treatment, cysteine also supports the health of lashes and brows, keeping them strong and protected. This amino acid not only improves the fibers’ elasticity but also helps shield them from mechanical and chemical damage, ensuring lasting results and a flawless appearance.

Contraindications

Cysteine is generally well-tolerated, but it is important to carry out a patch test to check for any adverse reactions. Do not use it if you have an allergy or intolerance to its components. If redness or irritation occurs, discontinue use immediately and consult your doctor.

Conclusions

Cysteine is a valuable ingredient in the cosmetics field due to its regenerating, protective, and strengthening properties. It is ideal for enhancing the appearance and resilience of hair, skin, and nails, and represents an innovative and sustainable choice for those seeking advanced cosmetic solutions that respect the environment.