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Glutathione

A small molecule the body makes from three amino acids. People take it by mouth hoping to lighten their skin.

Explained simply · Last reviewed 2026-09-26

What it is

Glutathione is a small molecule the body makes from three amino acids. Researchers in a 2018 trial describe it as the most abundant antioxidant the body makes, and a critical regulator of oxidative stress. They write that it is made from cysteine, glutamic acid and glycine. As a supplement it is sold as capsules and powders, as tablets that dissolve under the tongue, and in liposomal form.

More about Glutathione

Researchers in a 2018 trial describe it as the most abundant antioxidant the body makes, and a critical regulator of oxidative stress. They write that it is made from cysteine, glutamic acid and glycine. As a supplement it is sold as capsules and powders, as tablets that dissolve under the tongue, and in liposomal form.

The authors of a 2017 skin trial write that many people with darker skin look for whitening or lightening agents. They write that people who want fairer skin are given oral or even intravenous agents. Women, they add, are by far the majority of those who seek skin-whitening agents.

Injected and intravenous glutathione are not covered by this page's ratings. The FDA treats glutathione injections made by pharmacies as compounded drugs. The safety section reports one FDA alert about reactions to contaminated injections. This page has not reviewed the wider safety or effectiveness of injected glutathione.

All but one of the trials this page cites were funded in whole or in part by a company that supplied glutathione for them.

The open question with the capsules is simple to state: does swallowing glutathione raise the amount in the body? The ratings below report what the sources this page could read in full found.

Also known as: GSH, L-glutathione, reduced glutathione, liposomal glutathione

At a glance

Safety: known risks. See Safety ↓

Claims made about Glutathione, and how strong the evidence is for each:

Skin lightening when taken by mouth (lower melanin index)Evidence rating: Insufficient
Raises the body's glutathione levels when swallowed as a standard capsuleEvidence rating: Insufficient
Fatty liver disease not caused by alcohol (NAFLD), when taken by mouthEvidence rating: Insufficient

Each rating follows our published rules and the sources cited for it. We don’t add our own medical judgment. How we rate

Safety

Read this before the ratings below.

Risks

The US Food and Drug Administration (FDA) treats injectable glutathione made by pharmacies as a compounded drug, and this page does not rate it. In 2019 the FDA reported reactions in eight people given intravenous glutathione that pharmacies had made from a powder labeled as a dietary supplement. Seven, treated at one clinic, developed symptoms within minutes, including nausea, vomiting, light-headedness, chills, body aches and sneezing. One of them had low blood pressure and difficulty breathing and was taken to hospital. An eighth person was admitted to hospital with a possible bloodstream infection.
FDA testing found too much bacterial endotoxin in the powder those pharmacies received. The FDA states that powder labeled as a dietary supplement should not have been used to make sterile injectable drugs. This page has not reviewed the wider safety of injected glutathione.
In a 2017 12-week trial of oral glutathione for skin, 60 women enrolled and three stopped early: two because of raised liver enzyme tests, and one because she started taking oral contraceptives. The researchers describe the liver test rises as temporary, returning to normal within a few weeks. The paper does not say which study group those two women were in. It reported no serious adverse events among the 57 women analyzed. Adverse events (itching, skin redness, small red spots on the skin or tiredness) were reported in 2 of 18 women on oxidized glutathione, 3 of 20 on reduced glutathione and 4 of 19 on placebo.
In a 2011 four-week trial of oral glutathione in 40 healthy adults, 39 of whom were analyzed, the researchers report no serious or systematic adverse effects. They report no changes in clinical laboratory measures, including hematology and liver and kidney function tests, during glutathione supplementation. They describe the side effects reported as generally mild: five people reported increased flatulence and loose stools, two reported flushing and one reported weight gain. The paper does not say which study group those people were in.
In a 2017 four-month trial of oral glutathione in 32 people with fatty liver, which had no comparison group, three stopped early: one each because of fatigue, raised blood pressure and a rash. The authors write that glutathione may have been associated with the rash, and that its links to the other effects are unclear. HbA1c, a measure of average blood sugar, rose over the trial.

Safety sources: Source [1]Source [2]Source [3]Source [4]

What the evidence says

Each claim is rated on its own evidence. Ratings follow the scale on our methodology page.

Skin lightening when taken by mouth (lower melanin index) Evidence rating: Insufficient
People take glutathione by mouth hoping it will lighten their skin.
A 12-week trial in 57 women found no statistically significant difference in melanin from placebo overall, only on one forearm in a small group of women over 40.
Too little research to say. The one trial this page cites, read in full here, was a 12-week randomized, double-blind, placebo-controlled study. It enrolled 60 healthy women and analyzed 57. The company that supplied the capsules funded it. Across all women analyzed, melanin levels tended to be lower than with placebo, but the difference was not statistically significant.

The difference reached significance on one sun-exposed forearm in the women over 40, a subgroup of 7 on reduced glutathione and 10 on placebo. The authors call for further studies in larger and more diverse populations.

No systematic review is cited. Two that this page found exist, but this page could not obtain their full texts free of charge. So it has not read them, and their findings are not reported or counted here. Injections are not covered by this rating; the safety section reports one FDA alert about them.

Sources: Source [1]
Raises the body's glutathione levels when swallowed as a standard capsule Evidence rating: Insufficient
People swallow glutathione capsules hoping to raise the amount of glutathione in their body.
A four-week placebo-controlled trial in healthy adults found glutathione in red blood cells unchanged, with no trend toward a rise; its authors say a larger or longer study might find a response.
Too little research to say. This page cites no systematic review of the question, and one randomized, placebo-controlled trial. In that 2011 trial, four weeks of oral glutathione in 40 healthy adults (39 analyzed) left glutathione in red blood cells unchanged. Markers of oxidative stress did not change either.

Its authors conclude that short-term oral glutathione does not improve glutathione status in healthy adults. They also write that a response in a larger sample or with longer use cannot be ruled out. The trial measured markers in blood, cells and urine, not illness or other health outcomes. It was funded by the company that supplied the glutathione, and the authors declare no competing financial interests.

Another trial this page found exists, but this page could not obtain its full text free of charge. So it has not read it, and its findings are not reported or counted here.

Sources: Source [1]
Fatty liver disease not caused by alcohol (NAFLD), when taken by mouth Evidence rating: Insufficient
People with fatty liver disease take glutathione by mouth hoping it will help their liver.
Two small trials with no comparison group reported falls in the liver enzyme ALT after glutathione; in the one that scanned the liver, liver fat did not change significantly overall.
This page found no systematic review of glutathione for fatty liver, and no trial with a placebo or comparison group. Two small trials, read in full here, gave glutathione by mouth to everyone taking part. Each compared people's results with their own before they started glutathione. Neither examined liver tissue after the glutathione period or measured clinical outcomes, such as disease progression or symptoms.

A Japanese trial of 15 people with fatty liver confirmed by biopsy included 10 with the inflamed form of the disease (NASH). In them, the liver enzyme ALT and a marker of oxidative damage to DNA fell significantly after glutathione, but GGT, another liver enzyme, did not. In the 5 with simple fatty liver the falls were not statistically significant, a group too small to show whether there was an effect. That trial declares no funding and no conflicts of interest.

A second Japanese trial enrolled 34 people with fatty liver found on ultrasound. They began a diet and exercise program three months before glutathione, and 29 completed four months of glutathione. ALT fell significantly, as did triglycerides, free fatty acids and ferritin, while HbA1c, a measure of average blood sugar, rose. Liver fat and liver stiffness, measured by scan, did not change significantly across all patients.

Afterwards, the researchers split patients into two groups by how much their ALT had fallen, at the middle value. In the 15 whose ALT fell by at least that much, liver fat fell significantly on average; in the other 14, ALT on average rose. The authors list the lack of a control group, the small size and the short four-month period as limitations. They write that large trials are needed to confirm the effects. The company that supplied the glutathione provided partial funding, and the authors declare no competing interests.

A 2024 guideline from the Chinese Society of Hepatology lists reduced glutathione among several drugs used for liver injury in China that "have been found to assist in improving liver biochemical parameters" in chronic liver disease, including fatty liver. It states that "there is insufficient evidence supporting their histological benefits" in fatty liver. It cites no study of glutathione for that statement. The guideline does not say whether it means glutathione taken by mouth or by injection.

Sources: Source [1]Source [2]Source [3]

Which form the evidence used

Supplements are sold in several forms. This is what the sources on this page say about them — which form the research used, and any comparison those sources themselves made. Where they made none, this page does not rank the forms.

Standard glutathione (capsules or powder you swallow), What the sources supportDetails
The 2017 skin trial and the 2011 placebo-controlled trial of glutathione levels cited on this page both used this form. The 2011 trial found glutathione in red blood cells unchanged (see the ratings below). Source [1]Source [2]
Sublingual glutathione (a tablet dissolved under the tongue), What the sources supportDetails
One 2015 trial compared forms directly. In 20 adults with metabolic syndrome, each of whom took every product for three weeks in turn, plasma glutathione rose with a sublingual tablet and fell with standard capsules. The ratio of reduced to oxidized glutathione was higher with the tablet. The authors report these differences between the two forms as statistically significant. The maker of the sublingual tablet sponsored the trial, and two of the four authors are its employees. This is about blood markers, not about whether either form helps any of the claims rated below. Source [1]
Liposomal glutathione (glutathione carried in liposomes, taken by mouth), What the sources supportDetails
A 2018 pilot trial with no placebo group randomly assigned 12 healthy non-smoking adults (11 women) aged 51 to 72 to one of two amounts of a liposomal glutathione liquid for a month. Glutathione in blood and blood cells tended to rise from starting levels, significantly only at some time points. Oxidative stress markers tended to fall. Amounts did not differ, which the authors say may partly reflect the small size. They call the findings preliminary, and write that placebo-controlled trials and side-by-side comparisons of forms will be required. The product's supplier funded the trial and provided the glutathione, and two authors received research funding from it for the study. The trial measured blood markers, not the rated claims. Source [1]

Sources

Glutathione and its antiaging and antimelanogenic effects
Clinical, Cosmetic and Investigational Dermatology, 2017 · Randomized controlled trial · Supporting source
This source discloses industry funding.
Effects of Oral Glutathione Supplementation on Systemic Oxidative Stress Biomarkers in Human Volunteers
The Journal of Alternative and Complementary Medicine, 2011 · Randomized controlled trial · Supporting source
This source discloses industry funding.
Reduced Glutathione suppresses Oxidative Stress in Nonalcoholic Fatty Liver Disease
Euroasian Journal of Hepato-Gastroenterology, 2016 · Trial without a placebo group · Supporting source
Efficacy of glutathione for the treatment of nonalcoholic fatty liver disease: an open-label, single-arm, multicenter, pilot study
BMC Gastroenterology, 2017 · Trial without a placebo group · Supporting source
This source discloses industry funding.
Guideline for the Prevention and Treatment of Metabolic Dysfunction-associated Fatty Liver Disease (Version 2024)
Journal of Clinical and Translational Hepatology, 2024 · Clinical practice guideline · Supporting source
FDA highlights concerns with using dietary ingredient glutathione to compound sterile injectables
US Food and Drug Administration, 2019 · Health authority summary · Primary source
Effects of N-acetylcysteine, oral glutathione (GSH) and a novel sublingual form of GSH on oxidative stress markers: A comparative crossover study
Redox Biology, 2015 · Randomized controlled trial · Supporting source
This source discloses industry funding.
Some of its authors disclose ties to industry.
Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function
European Journal of Clinical Nutrition, 2018 · Trial without a placebo group · Supporting source
This source discloses industry funding.
Some of its authors disclose ties to industry.

Page history

Show all 7 changes to this page

2026-09-28 — Rewritten to the content style guideline; ratings and sources unchanged.
2026-09-26 — Revised after an audit of sources. Removed the two skin-lightening reviews and the 2015 trial of glutathione levels, because this page could not read their full texts. Skin lightening by mouth is now rated insufficient (was limited), resting on one trial. Raising glutathione levels with standard capsules is now rated insufficient (was limited), resting on one trial that found no change. Removed the safety statements that rested only on the two reviews, including the review's conclusion on intravenous glutathione, and the form note's sentence on absorption. Added the side effects reported in the 2011 trial and the adverse events by group in the 12-week skin trial. Narrowed the text on injections to the one FDA alert this page reports.
2026-09-26 — Added a rating for fatty liver disease not caused by alcohol (NAFLD), taken by mouth: insufficient, because the only trials found are two small studies with no comparison group. Restored the liposomal form entry, citing its pilot trial as a trial without a placebo group, a source type the site added on 2026-09-26. Added the fatty-liver trial's withdrawals to the safety section. Existing ratings unchanged.
2026-09-23 — Published. Both claims, the safety section and every source passed the site's source and wording reviews. The withdrawn FDA consumer update, the two skin reviews read from abstract only, and the missing source type for uncontrolled trials stay logged in docs/08-open-decisions.md.
2026-09-23 — Revised after source and wording review. Reworded to describe what was measured (melanin index) rather than how skin looks, attributed the treatment of injectable glutathione as a drug to the FDA, and removed detail about the letter that this page knew only from the trial authors' reply. Ratings unchanged.
2026-09-23 — Revised after source review. Oral safety now reports the 2025 review's "minimal versus substantial adverse effects" wording and the two temporary liver-test rises in the 12-week trial. Removed the liposomal form entry: its only source was a pilot study with no placebo group, which the site cannot yet label accurately. Ratings unchanged.
2026-09-23 — First drafted. Skin lightening by mouth and raising glutathione levels with standard capsules both rated limited.