Glutathione skincare glossary: 27 terms explained simply

By the GlutaNex team · Updated 14 October 2026 · 1 sources cited

Short, plain definitions of the terms used across our guides and on glutathione product labels. Each term links to the full guide where there is one.

Antioxidant

A substance that neutralises free radicals, the unstable molecules made by sunlight, pollution and normal metabolism. Glutathione, vitamin C and vitamin E are antioxidants. Glutathione guide

Broad-spectrum sunscreen

A sunscreen that protects against both UVB (burning) and UVA (tanning and ageing) rays. Summer tan guide

Ceramides

Natural fats in the outer skin layer that hold skin cells together and keep moisture in. Added to creams to support the skin barrier.

Cysteine

One of the three amino acids in glutathione. Its sulphur group is what lets glutathione act as an antioxidant. Glutathione-rich foods

Eumelanin

The dark brown-black type of melanin. Glutathione may shift production away from it.

Free radicals

Unstable molecules that damage cells. UV light and pollution increase them in skin.

GSH (reduced glutathione)

The active form of glutathione that neutralises free radicals. GSH vs GSSG

GSSG (oxidised glutathione)

Two glutathione molecules joined after doing their antioxidant job. More stable in lotions; the body can turn it back into GSH. GSH vs GSSG

Hyaluronic acid

A water-holding molecule found naturally in skin. In creams it draws water into the top layer so skin feels hydrated.

Hyperpigmentation

Any area of skin darker than the skin around it: tan, sun spots, acne marks or melasma. Pigmentation guide

Kojic acid

A brightening ingredient made by fungi that slows melanin production. Can irritate some skin. Glutathione vs kojic acid

Liposomal

Wrapped in tiny fat bubbles (liposomes), usually to help a supplement survive digestion. Liposomal glutathione

Melanin

The pigment that gives skin, hair and eyes their colour and helps protect skin from the sun. Glutathione guide

Melanin index

A number measured by a skin meter in studies to track how much melanin is in skin. Facts and figures

Melanocyte

The skin cell that makes melanin.

Melasma

Brown or grey-brown patches, usually on both cheeks, forehead or upper lip, linked to sun, hormones and genetics. Needs a dermatologist. Melasma guide

Niacinamide

Vitamin B3. Helps the look of uneven tone and supports the skin barrier. Often paired with glutathione. Glutathione and niacinamide

PA rating

A rating (PA+ to PA++++) used on Asian sunscreens for UVA protection. More plus signs mean more UVA protection.

Patch test

Trying a product on a small area, such as behind the ear, for 24 hours before using it on the face. Side effects

Pheomelanin

The lighter red-yellow type of melanin.

PIH (post-inflammatory hyperpigmentation)

Dark marks left after a pimple, cut, burn or rash heals. Common in Indian skin. Acne marks guide

Retinol

A form of vitamin A used at night for smoother-looking skin. Can cause dryness at first and makes skin more sun-sensitive. Retinol vs glutathione

Salicylic acid (BHA)

An oil-soluble acid that exfoliates inside pores. Helpful for oily skin; can sting on broken or shaved skin. Oily skin guide

SPF

Sun Protection Factor: how well a sunscreen protects against UVB. SPF 30 or higher is recommended for daily use.

Tripeptide

A small chain of three amino acids. Glutathione is a tripeptide of glutamic acid, cysteine and glycine. Glutathione guide

Tyrosinase

The enzyme skin uses to make melanin. Glutathione, kojic acid and vitamin C can slow it. Glutathione guide

Visible light

The light we can see. On brown skin it can deepen pigmentation such as melasma; tinted sunscreens with iron oxides help block it. Melasma guide

General information about cosmetic skincare, not medical advice. Results vary from person to person. See a dermatologist for persistent or changing pigmentation.