Cysteine

This naturally occurring sulfur-containing amino acid is used in cosmetic formulations. It's chosen for humectant and antioxidant functions that support moisture retention and product stability, without serving as a drug treatment.
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Ingredient Snapshot

Overview
An amino acid that draws in moisture and fights free radicals.
Category
Hydration, Skin Conditioning, Antioxidant
Type
Humectant

Ingredient Ratings

Overall Rating

Good

Comedogenic Risk

None

Skin Benefits

Draws moisture to the skin for a plumper, more supple feel and helps defend against oxidative stress. Supports a healthy-looking barrier without heaviness.

Uses In Skincare & Cosmetics

Used in hydrating serums, moisturizers, and sheet masks to boost water retention and comfort.

Comedogenic Rating

This ingredient is not typically evaluated for comedogenicity, and no standardized rating is available.

Safety

Generally well tolerated with low irritation potential in leave-on formulas. Rare users may notice mild transient stinging or a sulfurous odor; patch test if very sensitive.

Is Cysteine a Good Ingredient?

Good rating: a well-characterized amino acid humectant and antioxidant that supports hydration and stability with a generally low irritation profile. Its water solubility and compatibility make it a dependable supporting ingredient rather than a standout active, which keeps the rating at Good instead of Great.

Products with Cysteine

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