Does glutathione lighten skin?

What the reviews found

A 2025 systematic review looked at studies from the previous 10 years:^[1]

• 5 randomized trials and 1 open study gave glutathione by mouth: 250 mg once a day, 250 mg twice a day or 500 mg once a day. Compared with placebo, it lowered the melanin index, a measure of skin pigment.^[1]
• A cream with 0.5% glutathione worked better than a 0.1% cream and than placebo.^[1]
• A 2% glutathione cream together with glutathione by mouth worked better than either one alone.^[1]
• Only one placebo-controlled trial tested glutathione into a vein. 6 of 16 people (37.5%) responded with glutathione and 3 (18.7%) with placebo. The difference was not statistically significant.^[1]
• About half of the studies had a high risk of bias. The authors judged glutathione by mouth and cream moderately effective, and wrote that glutathione into a vein should not be used.^[1]

A 2019 systematic review found only 4 studies. It saw a trend toward lighter skin in areas exposed to the sun, and no significant difference in areas the sun does not reach. It called the evidence inconclusive, because the studies were of limited quality and their results differed.^[2]

Two trials

• 60 healthy medical students in Thailand took 500 mg a day, in two doses, or placebo for 4 weeks. The melanin index fell at all 6 measured sites. The difference from placebo was significant at only 2 of them: the right side of the face and the left forearm, which was exposed to the sun.^[3]
• 124 Asian women took 250 mg of glutathione, 500 mg of L-cystine, both together, or placebo every day for 12 weeks. The combination lightened the skin and made dark spots on the face smaller. It did better than placebo and better than either part alone.^[4] Two of the authors worked for BCF Life Sciences.^[4]

How it may work

Glutathione blocks tyrosinase, the enzyme that makes melanin, in direct and indirect ways. It also shifts melanin production from dark eumelanin to lighter phaeomelanin.^[5][4]

What is still unknown

A 2016 review said that it is not known how long to use glutathione, how long the effect lasts or how to keep it. It called for larger and longer placebo-controlled trials.^[5] The authors of the 4-week trial wrote that long-term safety has not been established.^[3]

Injections

Glutathione injections for lighter skin are popular, but there is no evidence that they work. Their side effects led the Food and Drug Administration of the Philippines to warn against this use.^[5] In the US, the FDA reported fever, chills and signs of shock in people who got glutathione injections made from supplement-grade glutathione.^[6]