Cysteamine HCl

BrighteningAntioxidant

INCI: Cysteamine HCl

In short · TL;DR

Category

Brightening

Effect

Suppresses melanin production and addresses the appearance of uneven color.

Concentration

The study used a 5% cream (Mansouri 2015). Whether it can be used in Japanese cosmetics is unconfirmed.

Effect

Suppresses melanin production and addresses the appearance of uneven color.

Mechanism

An endogenous aminothiol. Reported to suppress melanin production through copper chelation, reducing action, and effects on the tyrosinase/peroxidase system.

Typical concentration

The study used a 5% cream (Mansouri 2015). Whether it can be used in Japanese cosmetics is unconfirmed.

Onset

In a double-blind study (50 people) applying 5% cream once daily at bedtime for 4 months, pigmentation was lighter than placebo at both 2 and 4 months.

Cautions

A characteristic sulfur-like odor and transient irritation may occur. A patch test is recommended.

Evidence & references

Mansouri 2015 https://pubmed.ncbi.nlm.nih.gov/25251767/ (checked 2026-10-20)

This page is reference information and does not guarantee efficacy. Figures vary by test conditions (in vitro / manufacturer / concentration). It does not indicate pharmaceutical efficacy.

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