Glutathione: research, side effects and dosage in studies
In short
Glutathione is an antioxidant made of three amino acids that the body makes itself and that is sold as a food supplement. The trials measured blood values, not diseases [1, 5]A. Skin-lightening drips into a vein carry serious harms [12]regulator.
- Glutathione taken by mouth raised blood glutathione in a six-month trial [5]A, but not in a four-week trial [1]A.
- Taken by mouth it lightened skin moderately and temporarily [8].
- In August 2026 the FDA said it was aware of adverse events in at least 30 patients after glutathione given into a vein [12]regulator.
- In Finland glutathione is not on the medicines list, and food supplements are foods [14, 15]regulator. WADA does not name glutathione, but large infusions are prohibited [17]regulator.
What is glutathione?
Glutathione is a tripeptide, a chain of three amino acids (glutamic acid, cysteine and glycine), and it is the most abundant free radical scavenger the human body makes itself [1]A [3]regulator. It protects cells from oxidative damage and from the toxicity of foreign substances, and it maintains the redox balance of cells [2].
Glutathione occurs in food: freshly prepared meat is relatively high in it, fruits and vegetables have moderate to high amounts, and dairy products and cereals are low. Freezing preserved glutathione, but other forms of processing and preservation generally destroyed much of it [4]D.
Glutathione is used as an ingredient in food supplements on the EU market [3]regulator. Basics: What are peptides?. All substances: Peptides A-Z.
Evidence at a glance
Each cell gives the kind of study and its source. The letter is the evidence level, not the result.
| Claimed effect | Humans | Animals | Cells |
|---|---|---|---|
| Body glutathione stores | 54 adults, 6 months: levels rose [5]A; 40 adults, 4 weeks: no change [1]A | - | - |
| Oxidative stress | 40 adults, no change in markers [1]A | - | - |
| Fatty liver | 34 patients without a comparison group, liver enzyme fell [6]B | - | - |
| Skin lightening, by mouth | 60 students: difference from placebo at only 2/6 sites [7]A; moderate and temporary in a review [8] | - | - |
| Skin lightening, into a vein | Only one placebo-controlled trial [8]; limited evidence [11] | - | - |
| Safety | Well tolerated by mouth in short trials [7]A; serious adverse events into a vein [12]regulator | - | - |
"-" = no such study is known.
What is glutathione studied for?
In Finland glutathione has no approved medicinal use: it is not on the medicines list, and no glutathione medicine is recorded for Finland [13, 14]regulator. According to a review, in countries where injectable glutathione is a medicine it is approved only for severe liver disorders and for preventing nerve damage caused by chemotherapy [9]. Among EU and EEA countries, injectable glutathione medicines are recorded only for Italy [13]regulator.
- Body stores and oxidative stress: small randomised trials in healthy adults [1, 5]A.
- Fatty liver: one pilot study without a comparison group [6]B.
- Skin lightening: glutathione taken by mouth, applied to the skin or given into a vein [7]A [8, 11].
Claims online. Glutathione is advertised as a liver detox and a skin lightener, and intravenous glutathione is offered by clinics and online [10]. For fatty liver there is only one study without a comparison group [6]B, and according to a 2016 review there was no study of the long-term safety of intravenous use [10].
How does glutathione work?
Glutathione scavenges free radicals and protects cells from oxidative damage and from the toxicity of foreign substances [2]. The body makes it itself [1]A.
Results on absorption by mouth vary. In a six-month trial levels rose in a dose-dependent way [5]A, in a four-week trial they did not [1]A.
For the skin, the authors of a 2016 review describe glutathione shifting skin pigment from brown eumelanin to lighter, red-yellow pheomelanin [10].
Has glutathione been studied in humans?
Yes, but the glutathione trials are small and measure blood values, markers or skin colour, not prevention or treatment of disease [1, 5, 7]A.
Glutathione taken by mouth
- Body stores (2015). In a six-month placebo-controlled trial, 54 non-smoking adults received glutathione at two different doses or placebo. With the higher dose, glutathione rose by 30-35% in red blood cells, plasma and lymphocytes (a type of white blood cell), and levels returned to baseline after a one-month break. Natural killer cell activity more than doubled in the high-dose group at three months [5]A.
- Oxidative stress (2011). In a four-week randomised trial, 40 healthy adults received glutathione or placebo. No changes were seen in oxidative stress markers or in red blood cell glutathione [1]A.
- Fatty liver (2017). In an open-label single-arm pilot study, 34 patients with fatty liver first changed their lifestyle for three months and then took glutathione for four months. The liver enzyme ALT, triglycerides, free fatty acids and ferritin fell, but there was no comparison group, and the investigators consider large trials necessary [6]B.
Skin
- Student trial (2012). In a four-week trial in 60 medical students, glutathione reduced the melanin index at all six measurement sites, but the difference from placebo was significant at only two sites [7]A.
- Systematic review (2025). In five randomised trials, glutathione taken by mouth reduced the melanin index compared with placebo, but the effect was not lasting. There was only one placebo-controlled trial of intravenous glutathione, and about half of the studies had a high risk of bias [8].
- Intravenous glutathione (2026). According to a review, the evidence on skin lightening is limited and varied, studies are small with short follow-up, and vitamin C given at the same time makes it hard to judge the effect of glutathione itself [11].
Who studies glutathione?
The studies and reviews on skin lightening have been published in dermatology journals [7]A [8, 9]. As a food supplement, the safety of glutathione has been assessed by the European Food Safety Authority EFSA [3]regulator.
Who wrote this page: the editorial team
This page was written by the Molecular Recovery editorial team. The draft was made with the help of AI, and the claims were checked against the sources (AI policy). The page has not been medically reviewed. How we work: About us.
How long does glutathione stay in the body?
There are no exact data on the half-life of glutathione taken by mouth. In the six-month trial, blood glutathione levels returned to baseline after a one-month break [5]A.
EFSA treated sublingual and liposomal glutathione products separately, because their absorption differs from the usual form [3]regulator. So study results for one product form do not directly apply to another.
What are the side effects of glutathione?
Taken by mouth, glutathione was well tolerated in short trials [7]A. Glutathione given into a vein carries serious harms [12]regulator.
What users report. In the Reddit accounts we compiled (not research), 38 of 58 people (66%) reported some harm, most often: injection site pain or reaction (22, 38%), fatigue (5, 9%) and acne or skin change (4, 7%). People tend to post when something goes wrong, so this share does not tell how common harms are. The figures cover only injected and intravenous glutathione (injection 48, drip 10 people); glutathione taken by mouth is not in the data. Some writers used it to lighten their skin. The harms in detail: Glutathione user experiences.
By mouth
In a four-week skin trial glutathione and placebo were very well tolerated, but long-term safety has not been established [7]A. According to EFSA, human data on glutathione taken by mouth support the safety of the acetylated form in adults [3]regulator.
The French food agency ANSES assessed glutathione in 2008 as a source of amino acids, with cysteine the part most likely to cause adverse effects [3]regulator.
Into a vein
In August 2026 the FDA said it was aware of adverse events in at least 30 patients after intravenous glutathione. The glutathione was a dietary supplement grade ingredient that should not have been used for injectable products. Symptoms included fever, chills, pain, dizziness and shock-like and sepsis-like symptoms, and some patients were hospitalised [12]regulator.
According to a 2026 review, intravenous glutathione carries risks of liver injury and hypersensitivity reactions as well as possible kidney and hormonal effects [11]. The authors of a 2016 review considered that a shift in skin pigment from brown eumelanin to red-yellow pheomelanin may increase the risk of sun-induced skin cancers [10].
According to Fimea, impurities such as endotoxins that end up in injectable products during manufacture raise the risk of serious health hazards [16]regulator. More: Side effects and safety.
Interactions and who has no data
Little is known about interactions of glutathione with medicines. EFSA's safety assessment of the acetylated form concerns adults, and pregnant and breastfeeding women were excluded from it [3]regulator. According to the Finnish Food Authority, you should tell your doctor that you use a food supplement [15]regulator.
Evidence against and what is unknown
The results are mixed, and the trials measure blood values rather than health benefits [1, 5]A.
Evidence against
- In the four-week trial, oxidative stress markers and red blood cell glutathione did not change [1]A.
- In the student trial the difference from placebo was significant at only two of six sites [7]A.
- The authors of a systematic review consider intravenous glutathione contraindicated because of lack of efficacy and side effects [8].
What the evidence does not support
- "Glutathione is not absorbed by mouth at all": in a six-month trial levels rose in a dose-dependent way [5]A. In another trial they did not change [1]A.
- "Glutathione detoxes the liver": the evidence is scant. The only fatty liver study had no comparison group [6]B.
- "Glutathione injections are a safe way to lighten skin": there is only one placebo-controlled trial of intravenous glutathione [8], and serious harms have been reported to the FDA [12]regulator.
- "A health claim on a supplement means it treats disease": according to the Finnish Food Authority, claims about treating, preventing or curing disease can be allowed only for medicines [15]regulator.
What is not known
- Whether glutathione taken by mouth has health benefits. The trials measured blood values and markers rather than diseases [1, 5]A.
- Whether glutathione helps fatty liver. According to the authors, the pilot study needs large follow-up trials [6]B.
- How long skin lightening lasts and long-term safety [7]A [8].
- Long-term safety of intravenous glutathione. A 2016 review found no study of long-term use [10].
Glutathione dosage in studies
There is no approved medicinal dosing in Finland, because glutathione is not a medicine here [13, 14]regulator. Below are the amounts used in human studies. They are not instructions.
| Study | Who | Dose and route | Duration |
|---|---|---|---|
| Richie 2015 | 54 non-smoking adults | 250 mg or 1,000 mg per day by mouth | 6 months [5]A |
| Allen 2011 | 40 healthy adults | 500 mg twice per day by mouth | 4 weeks [1]A |
| Honda 2017 | 34 patients with fatty liver | 300 mg per day by mouth | 4 months [6]B |
| Arjinpathana 2012 | 60 medical students | 500 mg per day by mouth | 4 weeks [7]A |
According to a review, skin trials used 250 mg once or twice per day or 500 mg once per day [8]. EFSA assessed the acetylated form of glutathione (S-acetyl glutathione) as safe for adults up to 300 mg per day, excluding pregnant and breastfeeding women. The assessment concerns this form, for which novel food authorisation was sought [3]regulator.
What the numbers do not tell you. The amounts do not show whether glutathione has a health benefit, and long-term safety was not established in these trials [7]A. They say nothing about intravenous amounts. A fuller table with sources: Glutathione doses used in studies. Why the vial calculator does not cover this substance: glutathione and the calculator.
Glutathione by mouth vs into a vein: what is the difference?
They are different things in both evidence and risk.
- By mouth: several small randomised trials [1, 5, 7]A. Skin lightening was moderate and temporary [8]. Well tolerated in short trials [7]A.
- Into a vein: only one placebo-controlled skin trial [8], and a 2016 review found no study of long-term use [10]. Serious adverse events have been reported to the FDA [12]regulator.
Status in the United States
In the United States, the FDA reminded in August 2026 that dietary supplement grade glutathione must not be used to make injectable drugs. According to the FDA, ingredients labelled for dietary supplement use may contain impurities, including endotoxins, that can be harmful when injected [12]regulator.
Is glutathione legal in Finland?
Glutathione is not on the Finnish medicines list, and as a food supplement it is a food [14, 15]regulator.
- Food supplement. Food supplements are foods, and according to the Finnish Food Authority their labelling or advertising may not make claims about treating, preventing or curing disease [15]regulator.
- EFSA. According to an opinion published in September 2026, glutathione is used in food supplements on the EU market, and novel food authorisation has been sought for its acetylated form [3]regulator.
- Injectable product. According to Fimea, a product injected through the skin may be a medicine in Finland [16]regulator. Italy has glutathione medicines for injection into a muscle or vein, but none was recorded for Finland (data as of 21 Sep 2026) [13]regulator.
- Import. Ordering medicines from outside the EU is covered on Peptides and the law. Bringing them back from travel: Travelling with peptides.
This is not legal advice. Disclaimer.
Is glutathione doping?
The WADA 2026 Prohibited List does not name glutathione. However, intravenous infusions or injections of more than a total of 100 ml per 12 hours are prohibited (M2.2) unless received in hospital treatment, surgery or clinical diagnostic investigations [17]regulator.
How to assess a glutathione product
Dietary supplement grade glutathione is not meant for injection: according to the FDA it may contain impurities such as endotoxins [12]regulator. According to the Finnish Food Authority, getting a food supplement online from an unknown seller can be a risk, and when ordering online you should check whether the product may be regarded as a medicine in Finland [15]regulator.
The product form matters: EFSA treated sublingual and liposomal products separately [3]regulator. On certificates of analysis (COA): How to read a COA and check a test result.
FAQ
Glutathione: where does it come from?
The body makes glutathione itself [1]A. In food it is found mainly in fresh meat and in fruits and vegetables, less in dairy products and cereals [4]D.
Glutathione benefits: what do studies show?
In a six-month trial, glutathione taken by mouth raised body glutathione stores [5]A, but in a four-week trial oxidative stress markers did not change [1]A. Prevention or treatment of disease was not measured.
Glutathione and the liver: does it help?
Not known. In one uncontrolled pilot study of 34 patients with fatty liver, the liver enzyme ALT fell, but the investigators say large trials are needed [6]B.
Glutathione experiences: what do studies say?
In skin trials the lightening was moderate and temporary [7]A [8], and serious harms have been reported with intravenous use [12]regulator.
What do users themselves report about glutathione?
In the Reddit accounts of 58 people we compiled (not research), 23 (40%) reported some benefit and 38 (66%) some harm. The accounts are self-selected and prove neither that it works nor that it is safe: Glutathione user experiences.
Glutathione side effects: what is known?
Taken by mouth, glutathione was well tolerated in short trials [7]A. For glutathione given into a vein, adverse events in at least 30 patients have been reported to the FDA, and some were hospitalised [12]regulator.
Glutathione dosage: what did studies use?
We do not give dosing instructions. The amounts used in studies are listed under Glutathione dosage in studies [1, 5]A. They are not a recommendation.
Glutathione at the pharmacy: is it a medicine in Finland?
No. Glutathione is not on the Finnish medicines list [14]regulator, and no medicine containing glutathione was recorded for Finland [13]regulator. Food supplements are foods [15]regulator, but according to Fimea an injectable product may be a medicine [16]regulator.
Glutathione and doping: is it banned?
Not by name. However, intravenous infusions of more than 100 ml per 12 hours are prohibited except in hospital treatment and investigations [17]regulator.
Read the research yourself: sources
Every source opens the original publication or the regulator's page. The level shows what the source itself reports.
- Allen J, Bradley RD. Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers. J Altern Complement Med. 2011;17(9):827-833. PMID 21875351 A
- Forman HJ, Zhang H, Rinna A. Glutathione: overview of its protective roles, measurement, and biosynthesis. Mol Aspects Med. 2009;30(1-2):1-12. PMID 18796312 (review)
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA); Turck D, Bohn T, Cámara M, et al. Safety of S-acetyl glutathione as an novel food pursuant to Regulation (EU) 2015/2283. EFSA J. 2026;24(9):e10258. PMID 42683004 regulator
- Jones DP, Coates RJ, Flagg EW, et al. Glutathione in foods listed in the National Cancer Institute's Health Habits and History Food Frequency Questionnaire. Nutr Cancer. 1992;17(1):57-75. PMID 1574445 D
- Richie JP Jr, Nichenametla S, Neidig W, et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Eur J Nutr. 2015;54(2):251-263. PMID 24791752 A
- Honda Y, Kessoku T, Sumida Y, et al. Efficacy of glutathione for the treatment of nonalcoholic fatty liver disease: an open-label, single-arm, multicenter, pilot study. BMC Gastroenterol. 2017;17(1):96. PMID 28789631 B
- Arjinpathana N, Asawanonda P. Glutathione as an oral whitening agent: a randomized, double-blind, placebo-controlled study. J Dermatolog Treat. 2012;23(2):97-102. PMID 20524875 A
- Sarkar R, Yadav V, Yadav T, P J, Mandal I. Glutathione as a skin-lightening agent and in melasma: a systematic review. Int J Dermatol. 2025;64(6):992-1004. PMID 39444151 (review)
- Sonthalia S, Jha AK, Lallas A, Jain G, Jakhar D. Glutathione for skin lightening: a regnant myth or evidence-based verity? Dermatol Pract Concept. 2018;8(1):15-21. PMID 29445569 (review)
- Davids LM, Van Wyk JC, Khumalo NP. Intravenous glutathione for skin lightening: Inadequate safety data. S Afr Med J. 2016;106(8):782-786. PMID 27499402 (review)
- Aloraini K, Alangari A, Arif J, Alkhodairy F. Glutathione for skin lightening via intravenous, oral, and topical routes: a critical narrative review of current evidence, safety, and the evidence-practice gap. J Med Life. 2026;19(7):511-523. PMID 42751591 (review)
- U.S. Food and Drug Administration. FDA reminds compounders not to use dietary supplement grade glutathione for injectables (27 Aug 2026). FDA regulator
- European Medicines Agency. Article 57 product data (EMA/518502/2018, data as of 21 Sep 2026): intramuscular/intravenous glutathione medicines recorded for Italy only. EMA regulator
- Finland. Lääkeluettelo (Fimea medicines list), 230/2025, annexes 1 and 1 A. Finlex regulator
- Ruokavirasto (Finnish Food Authority). Ravintolisät (food supplements: advice for consumers). Ruokavirasto regulator
- Fimea. Fimea varoittaa: älä käytä verkosta ostettuja pistettäviä peptidejä / Fimea warns: do not use injectable peptides purchased online. 29 Jun 2026. Fimea regulator
- World Anti-Doping Agency. 2026 Prohibited List. WADA regulator
Sources checked 12 Oct 2026. The Fimea warning does not name glutathione.
Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed · regulator = a regulator's assessment or decision, not research evidence. The marker official means official product information (summary of product characteristics or label); it is not research evidence. For a review, the level shows what kind of research the statement rests on. No level: statements that something has not been studied, reviews' interpretations, named hypotheses and the general rules in our certificate-of-analysis guide.
Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.