What is it?
Oxidized glutathione, also called glutathione disulfide or GSSG, is two molecules of glutathione linked by a disulfide (sulfur-to-sulfur) bond. Glutathione is a small peptide made of three amino acids, cysteine, glycine and glutamate, that the human body makes on its own and uses as a major antioxidant. In cosmetics, oxidized glutathione is used in skin care as a skin conditioning agent and emollient.
Key information
- Oxidized glutathione (GSSG) is two linked molecules of glutathione, an antioxidant the body makes naturally.
- In a 10-week placebo-controlled trial of a 2 percent lotion in 30 women, researchers reported no marked adverse effects.
- We found no independent safety review of it by the CIR or the EU's SCCS.
- Skin-lightening glutathione injections are a separate issue; a 2025 review concluded intravenous use is contraindicated.
More information
In the body, glutathione cycles between its reduced form (GSH) and its oxidized form (GSSG). An enzyme, glutathione reductase, converts GSSG back to GSH, and together the two take part in many reactions that neutralize free radicals and harmful substances.
We found no safety review of oxidized glutathione by the Cosmetic Ingredient Review (CIR) or the EU’s Scientific Committee on Consumer Safety (SCCS), and the EU places no restrictions on it in cosmetics. The main human evidence is a 2014 randomized, double-blind, placebo-controlled trial in 30 healthy women aged 30 to 50. They applied a 2 percent oxidized glutathione lotion to one side of the face and a placebo lotion to the other, twice a day for 10 weeks. The researchers reported no marked adverse effects. They also measured less melanin (skin pigment) on the treated side.
Reality check: glutathione is also sold as a skin-lightening agent in pills and injections, which are a different matter from a cosmetic lotion. A 2025 systematic review found that topical glutathione had minimal adverse effects while oral glutathione had more substantial ones, and it concluded that intravenous glutathione is contraindicated because of lack of efficacy and side effects. On labels, look for “oxidized glutathione”; plain “glutathione” is the reduced form.
Sources: European Commission CosIng: Oxidized Glutathione; PubChem: Glutathione disulfide; Clinical, Cosmetic and Investigational Dermatology (2014): Topical oxidized glutathione, a double-blind, placebo-controlled trial in healthy women; International Journal of Dermatology (2025): Glutathione as a skin-lightening agent and in melasma, a systematic review
