Ingredient Research
Glutathione for Skin GSH and GSSG
The body's own antioxidant, shown in a double-blind, placebo-controlled trial to brighten the look of skin.
−10.7%
Skin pigment in 10 weeks
Melanin index on the glutathione side of the face, against −3.1% on the placebo side (p < 0.001), in a double-blind trial of 30 women (Watanabe et al., 2014).
77%
Saw brighter-looking skin
77% of the women rated the glutathione side moderately brighter at week 10, against 23% for the placebo side. The investigator's ratings: 67% against 3% (Watanabe et al., 2014).
Week 1
First measurable change
The melanin index was already significantly lower on the glutathione side at week 1. By week 6, 87% of the women saw at least a slight brightening, against 10% on the placebo side (Watanabe et al., 2014).
What Is Glutathione?
Glutathione is a tripeptide antioxidant that the body makes in its own cells, used in skincare for brighter-looking skin. In a double-blind, placebo-controlled trial, a lotion with 2% oxidised glutathione (GSSG) lowered skin pigment by 10.7% in 10 weeks, against 3.1% on the placebo side of the face.
Skin pigment was read by a Mexameter probe as the melanin index, not judged by eye alone.
Written by the Skingenetix Research Team, which compiles the claims registers behind these pages.
By Skingenetix. Medically reviewed by Dr Esther Bodde, Cosmetic & Medical Physician. Every figure checked against the published paper or its PubMed record. Last reviewed 26 September 2026.
At a glance
- What it is: a tripeptide of three amino acids: glutamic acid, cysteine and glycine. In skincare, oxidised glutathione (GSSG) is used for a brighter-looking complexion.
- Best evidence: skin pigment −10.7% in 10 weeks against −3.1% for placebo (p < 0.001), and 77% of the women saw brighter-looking skin, in a double-blind, split-face trial of 30 women run by Kyowa Hakko Bio, the company that makes GSSG (Watanabe et al., 2014).
- Independent evidence: in an independent double-blind trial, a serum with 2% glutathione and vitamin C lowered skin pigment against a placebo serum in 8 weeks (Wahab et al., 2021); an academic systematic review concluded that topical 2% oxidised glutathione "could brighten skin color in sun-exposed area" (Dilokthornsakul et al., 2019).
- Not shown: results on fair skin (types I and II) or in men; no independent trial has yet tested oxidised glutathione on its own.
- Safety: no reactions attributed to glutathione in 76 women across two controlled trials of 8 and 10 weeks. Patch-test first.
- How to use: morning and evening for at least 10 weeks, with SPF in the morning.
Glutathione features in our brightening and glow routine.
What Does Glutathione Do for Skin?
Why skincare uses GSSG. Skin holds less glutathione with age and sun exposure (Rhie et al., 2001). The reduced form, GSH, breaks down quickly in water, so creams and serums use the oxidised form, GSSG (Watanabe et al., 2014).
Here is what the evidence shows, strongest first. Each line opens the study behind it.
The manufacturer's trial used a lotion with 2% oxidised glutathione, applied twice a day; the independent trial used a serum with 2% glutathione and vitamin C. Read our appraisal of the manufacturer's 30-woman split-face trial.
Before
After 10 weeks
Skin pigment −10.7% vs −3.1% on placebo (10‑week trial)
Brighter-Looking Skin: Pigment −10.7%
In a double-blind split-face trial, 30 women aged 30 to 50 used a 2% oxidised glutathione (GSSG) lotion on one half of the face and a placebo lotion on the other, twice a day for 10 weeks.
Results on the glutathione side:
- Skin pigment −10.7% (melanin index), against −3.1% on the placebo side, lower from week 1 (p < 0.001 at week 10)
- 77% of the women saw brighter-looking skin at week 10, against 23% on the placebo side
Watanabe F et al. (2014). Clin Cosmet Investig Dermatol, 7:267–274. View on PubMed
Before
After 10 weeks
Crow's feet visibly softer in 1 in 3 women, none on placebo
Softer-Looking Crow's Feet in 1 in 3 Women
In the same trial, rated at the outer corner of the eye at week 10:
- A third of the women had visibly softer crow's feet on the glutathione side: 33% against 0% on placebo by the investigator, 30% against 0% by the women
- 9 in 10 showed at least a slight improvement, against about 1 in 4 on placebo
The authors: the lotion "effectively reduced wrinkle formation in both objective and subjective evaluation tests".
Independent Trial: Skin Pigment −10.8% in 8 Weeks
In a double-blind trial at Hasanuddin University, Indonesia, 46 women used a serum with 2% glutathione and vitamin C on one cheek and a placebo serum on the other, twice a day for 8 weeks. In the 23 who took no oral glutathione:
- Skin pigment −10.8% (melanin index) on the serum side, while the placebo side rose 1.8% (p = 0.029)
- Brighter-looking skin on the colour meter (p = 0.046)
No funding and no conflicts of interest declared.
Wahab S et al. (2021). Int J Dermatol, 60(8):1013–1018. View on PubMed
Smoother, Better-Moisturised Skin, Measured by Instrument
In the same 10-week trial of 2% oxidised glutathione, instruments measured the skin at the outer corner of the eye and on the cheek.
- Smoother texture from week 6 to week 10 on the glutathione side, by skin-surface analysis
- Higher skin moisture at weeks 8 and 9, by Corneometer (p < 0.05)
Well Tolerated by 76 Women in Two Trials
In the 10-week trial of 2% oxidised glutathione, all 30 women completed twice-daily use, and the authors reported "no adverse reactions related to GSSG".
In the 8-week independent trial, none of the 46 women showed or reported redness, swelling, stinging or itching.
Same trial: Watanabe et al., 2014, on PubMed
Wahab S et al. (2021). Int J Dermatol, 60(8):1013–1018. View on PubMed
Glutathione Results: What the Trial Measured
Two charts from the double-blind trial of 2% oxidised glutathione (Watanabe et al., 2014): what the instrument recorded, and how many women and the investigator saw a difference.
Skin pigment after 10 weeks
Melanin index on the cheekbone, change from the start. 30 women, 2% GSSG lotion on one half of the face and placebo on the other, twice a day.
2% GSSG side
Placebo side
| Side of face | Change in melanin index |
|---|---|
| 2% GSSG side | −10.7% |
| Placebo side | −3.1% |
Left of zero is a reduction in pigment, so further left is brighter. The means: GSSG side 272.8 to 243.5, placebo side 274.1 to 265.5. The GSSG side was significantly lower than the placebo side from week 1 to week 10 (p<0.001 at week 10). Percentages are calculated from the paper's reported means (Watanabe et al., 2014).
Who saw a moderate improvement at week 10
Share of the 30 women given a score of 2 ("moderate change or improvement") on each side of the face, by the women themselves and by the blinded investigator.
2% GSSG sidePlacebo side
Brighter skin, rated by the women
Brighter skin, rated by the investigator
Softer crow's feet, rated by the women
Softer crow's feet, rated by the investigator
| Rating at week 10 | 2% GSSG side | Placebo side |
|---|---|---|
| Brighter skin, rated by the women | 76.7% | 23.3% |
| Brighter skin, rated by the investigator | 66.7% | 3.3% |
| Softer crow's feet, rated by the women | 30.0% | 0% |
| Softer crow's feet, rated by the investigator | 33.3% | 0% |
The trial's scale runs from 0 (no change) to 2 (moderate change). The paper labels this scale with an older lightening term; this page calls the same result brighter-looking skin (Watanabe et al., 2014, Table 3).
What 2% Glutathione Means
2% means 2 grams of glutathione in every 100 grams, or 20,000 parts per million. The manufacturer's trial used 2% oxidised glutathione (GSSG), twice a day, and the independent trial a serum with 2% glutathione and vitamin C. Our Glutathione 2% Brightening Serum states its 2% on the pack.
How to Use Glutathione
- 1Start cleanMorning and evening, on freshly cleansed skin, as both trials did.
- 2Give it ten weeksSmooth a few drops over the face twice a day. The pigment reading was lower from week 1, most women saw a first change by week 6, and the trial measured its main result at week 10.
- 3Finish with SPFEvery morning, as the last step of your routine, as in the independent trial.
Glutathione is not an acid or an exfoliant, so it layers easily with niacinamide, vitamin C and hyaluronic acid. For a daytime routine, follow it with a light cream such as our copper peptide (GHK-Cu) gel-cream, and patch-test any new product first.
Glutathione Evidence & Sources
Every study this page relies on, with its published title, our reading of it and a link to the source. Graded A controlled human trial measured by instrument · C human skin samples · Review a summary of other work.
| Study | Grade | What it found |
|---|---|---|
Skin-whitening and skin-condition-improving effects of topical oxidized glutathione: a double-blind and placebo-controlled clinical trial in healthy women Watanabe F, Hashizume E, Chan GP, Kamimura A, 2014 · Clin Cosmet Investig Dermatol · 7:267–274 View on PubMed → | A | 30 women aged 30–50, 10 weeks, randomised, double-blind, split-face. Skin pigment −10.7% against −3.1% on placebo (p < 0.001); 77% against 23% saw brighter-looking skin; crow's feet visibly softer in 1 in 3 women against none; smoother and better-moisturised by instrument. Run by Kyowa Hakko Bio, the GSSG manufacturer. |
Combination of topical and oral glutathione as a skin-whitening agent: a double-blind randomized controlled clinical trial Wahab S, Anwar AI, Zainuddin AN, Hutabarat EN, Anwar AA, Kurniadi I, 2021 · Int J Dermatol · 60(8):1013–1018 View on PubMed → | A | A serum with 2% glutathione and vitamin C lowered skin pigment 10.8% in 8 weeks against a placebo serum on the other cheek (p = 0.029), and brightened the colour-meter reading (p = 0.046). No reactions in 46 women. Independent: no funding, no conflicts of interest. |
The clinical effect of glutathione on skin color and other related skin conditions: A systematic review Dilokthornsakul W, Dhippayom T, Dilokthornsakul P, 2019 · J Cosmet Dermatol · 18(3):728–737 View on PubMed → | Review | An academic systematic review: topical 2% oxidised glutathione "could brighten skin color in sun-exposed area". |
Systematic Review of the Efficacy and Safety of Topical Glutathione in Dermatology Khanna R, Rambhia P, Chapas A, 2025 · J Clin Aesthet Dermatol · 18(9):51–54 View on PubMed → | Review | A review of five topical trials: topical glutathione "shows promise for dermatological applications". No conflicts of interest declared. |
Aging- and photoaging-dependent changes of enzymic and nonenzymic antioxidants in the epidermis and dermis of human skin in vivo Rhie G et al., 2001 · J Invest Dermatol · 117(5):1212–1217 View on PubMed → | C | Glutathione was lower in naturally aged and sun-aged human skin than in young skin. |
Published titles are quoted exactly as they appear in the journal.
Frequently Asked Questions
Everything you need to know about topical glutathione.
What is glutathione?
Glutathione is a tripeptide, a small molecule of three amino acids (glutamic acid, cysteine and glycine), that every cell in the body makes for itself. It is one of the body's primary antioxidants. In skincare it is used, as oxidised glutathione (GSSG) or reduced glutathione (GSH), for brighter-looking skin: in a placebo-controlled trial, a 2% GSSG lotion lowered skin pigment by 10.7% in 10 weeks.
Does topical glutathione work for brightening skin?
For a brighter-looking result on sun-exposed skin, yes, in the two controlled trials that measured it. In a double-blind, placebo-controlled trial, 2% oxidised glutathione lowered skin pigment by 10.7% in 10 weeks, against 3.1% for placebo (p < 0.001), and 77% of the women saw brighter-looking skin on the treated side, against 23%. An independent trial found the same direction with a serum of 2% glutathione and vitamin C (−10.8% in 8 weeks, p = 0.029). That is two small trials, 76 women in all, so it is good evidence for that one effect and no evidence for anything else. Both tested the ingredient at 2%, the level in our serum; the serum's own formula has not been trialled.
How long does topical glutathione take to work?
The pigment reading was significantly lower from week 1. By week 6, 87% of the women saw at least a slight brightening on the treated side, against 10% on the placebo side, and at week 10, 77% rated it moderately brighter. Use it morning and evening for at least 10 weeks. The trial measured the effect during use; what happens after stopping was not studied.
Can glutathione be absorbed through the skin?
The trial measured the treated side of the face against the untreated side, and only the treated side changed, so the effect appears where the product is applied. In that controlled trial, 2% GSSG lowered the treated side's pigment reading from week 1, against a placebo on the other side. Whether glutathione passes through the skin has not been measured in people. Skincare uses GSSG because it is the stable form: reduced glutathione, GSH, breaks down quickly in water.
What is the difference between GSH and GSSG?
GSH is reduced glutathione, the form that does the antioxidant work inside cells and makes up most of the body's glutathione. GSSG is oxidised glutathione: two GSH molecules joined by a disulfide bond. It is the more stable of the two in water, which is why the brightening trial used it.
Is topical glutathione safe?
In two controlled trials, 76 women used topical glutathione twice a day for 8 to 10 weeks. One had mild facial redness on days 2 and 3 that settled without stopping; no reaction was attributed to glutathione. As with any new product, patch-test first.
Who should be careful with topical glutathione, and is it the same as oral or IV glutathione?
A cream or serum is a cosmetic applied to the skin. It is not the oral supplements or the intravenous infusions discussed online; their results and their risks do not apply to a topical product. In the 10-week trial, one woman had mild facial redness on days 2 and 3 that settled without stopping; in the 8-week trial, none of the 46 women reported redness, swelling, stinging or itching. Our serum has no tolerance study of its own, so patch-test any new product first. It has not been tested in pregnancy or while breastfeeding, so ask your doctor or pharmacist first. Do not apply it to broken skin, keep it away from the eyes, and see a pharmacist or dermatologist if a reaction persists.
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Explore Our Glutathione Serum
Our Glutathione 2% Brightening Serum pairs glutathione with a stable form of vitamin C and niacinamide. Apply it morning and evening, follow with SPF, and give it at least 10 weeks.