Peptides

Pentapeptide-29 Cysteinamide

INCI: PENTAPEPTIDE-29 CYSTEINAMIDE

Reviewed by Daisy · Last updated 2 Jun 2026

Also known as: Pentapeptide-29 Cysteinamide

A peptide derivative that may help regulate melanin production and protect skin's redox balance

Best For Skin Types

All

Addresses

Hyperpigmentation, Uneven skin tone, Dark spots

Usage Frequency

Daily

What Is Pentapeptide-29 Cysteinamide?

Pentapeptide-29 Cysteinamide is a synthetic peptide derived from cysteine, a sulfur-containing amino acid central to skin physiology. It is created by chemically modifying cysteine to improve its stability and skin penetration compared to the amino acid in its raw form.

This ingredient works primarily by influencing the pathways involved in melanin synthesis. Cysteine and its derivatives play a role in regulating tyrosinase, an enzyme that controls the production of melanin, the pigment responsible for skin colour. By modifying cysteine into a peptide form, the ingredient may offer improved bioavailability and targeted effects on pigmentation processes.

How It Works

Pentapeptide-29 Cysteinamide works by interfering with the biochemical pathways that lead to melanin synthesis. Specifically, it inhibits tyrosinase-mediated dopachrome formation—an early step in the production of eumelanin (dark melanin). This modulation occurs at the enzymatic level, reducing the rate at which melanin is manufactured within melanocytes.

The peptide form offers advantages over free cysteine: it is more chemically stable in formulations and may penetrate the skin more effectively. The sulphur-containing structure of cysteinamide also contributes to the skin's redox regulation, supporting broader cellular protective mechanisms.

Clinical Evidence & References

In-vitro research demonstrates that cysteinamide is a potent inhibitor of tyrosinase-mediated dopachrome formation and reduces melanin content in cultured melanoma cells. Studies comparing it to other thiol compounds and established depigmenting agents (such as kojic acid and β-arbutin) suggest cysteinamide has inhibitory properties comparable to or potentially stronger than some established alternatives.

However, evidence from human clinical trials remains limited. Most data comes from laboratory and cell-based studies. Translating these findings to real-world efficacy in human skin—particularly regarding the degree of visible pigmentation change—requires further investigation. The ingredient shows theoretical promise for hyperpigmentation concerns, but claims should be treated with appropriate caution until in-vivo human data accumulates.

How to Use

Pentapeptide-29 Cysteinamide is typically found in serums, treatments, and targeted pigmentation formulas. Apply to clean skin before moisturiser, or layer into your routine as directed by the product instructions. Consistency matters: the effects of melanin-regulating ingredients develop over weeks to months, so regular use is necessary. If using multiple active ingredients, introduce peptide products gradually to monitor tolerance.

Safety & Precautions

Cysteine derivatives are generally well-tolerated in cosmetic formulations. No specific safety concerns have been widely documented for pentapeptide-29 cysteinamide in topical skincare use.

Frequently Asked Questions

From the Clinic

Not sure what your skin actually needs?

Two minutes, a few questions, and we’ll point you at what matters — no guesswork.

Take the skin quiz

Learn More About Skincare Ingredients

Explore our comprehensive ingredient glossary to understand what's in your products.

Browse All Ingredients

Authorised Stockist

Official UK retailer

Tracked Delivery

Free UK shipping over £50

5 Star Rating

Trusted by thousands

Expert Advice

Free consultations