Glutathione
A single 3 g oral dose did not raise blood glutathione. Over 6 months, daily oral doses raised body stores 30% to 35%. A 4-week trial found no change. Small trials found a lower skin melanin index. A 2016 review found no safety studies of IV use for skin lightening. FDA reported reactions to an endotoxin-contaminated IV batch.
Add to Bio HackChecked 2026-11-09
- Status
- Oral glutathione is sold as a dietary supplement in the US. IV glutathione in the US is made by compounding pharmacies. In 2019 FDA warned compounders against using one dietary-supplement-grade powder for injectables.
- Also called
- GSH, reduced glutathione, L-glutathione, liposomal glutathione, sublingual glutathione, S-acetyl glutathione, IV glutathione, glutathione drip, glutathione injection
- Taken for
- skin lightening, skin brightening, melasma, antioxidant, detox, liver health, immunity, anti-aging, Parkinson's disease, chemotherapy side effects
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help2
Reported risks1
What people take it for, and what was found
Shown to help2
Skin lightening (oral and topical)
Small trials found a lower melanin index on sun-exposed skin with oral or topical glutathione. Reviewers rated the evidence inconclusive or at high risk of bias.
The numbers and sources
- Effect
- In a review of 4 studies, oral glutathione at 500 mg a day and topical 2% oxidized glutathione lowered the melanin index on sun-exposed skin. Sun-protected skin showed no significant change [4]. A 2025 review found 5 trials and one open study of oral doses of 250 to 500 mg a day that lowered the melanin index against placebo [5].
- Population
- Healthy volunteers in 4 studies [4]; trials in the 2025 review [5].
- Sources
- [4], [5]
- Caveats
- The 2019 authors called the evidence inconclusive, citing study quality and inconsistent findings [4]. The 2025 review rated about half the studies at high risk of bias [5].
Liver function in chronic hepatitis B
One trial without placebo found lower ALT when glutathione was added to entecavir for 3 months in chronic hepatitis B.
The numbers and sources
- Effect
- In one trial, reduced glutathione added to entecavir for 3 months lowered ALT to 31.11 U/L against 56.90 U/L on entecavir alone, from about 348 U/L in both groups. Fibrosis markers fell more, and HBV DNA was undetectable at 48 weeks in 68.89% against 42.22% [10].
- Population
- 90 patients with chronic hepatitis B [10].
- Sources
- [10]
- Caveats
- One trial without placebo. The abstract does not state the glutathione dose or route [10].
Mixed results3
Raising the body's glutathione (oral)
Small trials found mixed results: single and 4-week doses did not raise glutathione, while 1,000 mg a day for 6 months raised it 30% to 35%.
The numbers and sources
- Effect
- Sources disagree. After a single 3 g dose, plasma glutathione did not rise significantly, and the authors judged systemic availability negligible [1]. Over 4 weeks of 500 mg twice a day, red cell glutathione and oxidative stress markers did not change [2]. Over 6 months, 1,000 mg a day raised glutathione 30% to 35% in red cells, plasma and lymphocytes. Levels returned to baseline a month after stopping [3].
- Population
- 7 healthy volunteers [1]; 40 healthy adults [2]; 54 nonsmoking adults [3].
- Sources
- [1], [2], [3]
- Caveats
- All three studies were small and differed in dose and length.
Nerve damage from chemotherapy (IV)
One trial found less nerve damage from oxaliplatin with IV glutathione. A larger review found no drop in all-grade neuropathy against placebo.
The numbers and sources
- Effect
- After 8 cycles, grade 2 to 4 neuropathy occurred in 2 patients on glutathione and 11 on placebo (P = 0.003). After 12 cycles, it was 3 against 8 (P = 0.004). Tumor response did not fall (26.9% against 23.1%) [7]. A 2026 network meta-analysis of 25 RCTs (1,625 patients) of glutathione and glutathione boosters found no agent lowered all-grade neuropathy against placebo. Glutathione was associated with fewer grade 3 or 4 cases (OR 0.34, 95% CrI 0.13 to 0.79) [8].
- Population
- 52 people with advanced colorectal cancer receiving oxaliplatin, given 1,500 mg/m² IV before each dose [7]. 1,625 patients receiving chemotherapy in 25 RCTs [8].
- Sources
- [7], [8]
- Caveats
- The grade 3 or 4 association was not retained when the analysis was restricted to double-blind studies, and the authors call it preliminary [8].
Parkinson's disease
Limited evidence: intranasal glutathione raised brain glutathione modestly without improving Parkinson's symptoms.
The numbers and sources
- Effect
- A 2026 systematic review of 9 studies (196 participants) of N-acetylcysteine or glutathione in Parkinson's disease found intranasal glutathione gave modest increases in brain glutathione without significant improvement in symptoms or oxidative stress markers [9].
- Population
- People with Parkinson's disease in RCTs and non-randomized studies from 2009 to 2019 [9].
- Sources
- [9]
- Caveats
- Small samples, short durations and varied doses and routes. The authors call the glutathione findings inconclusive [9].
Not shown to help1
Skin lightening (IV)
One trial found lightening in 37.5% on IV glutathione against 18.7% on placebo, a difference that was not significant.
The numbers and sources
- Effect
- One placebo-controlled trial of IV glutathione was found. Lightening occurred in 6 of 16 on glutathione (37.5%) and 3 on placebo (18.7%), P = 0.054 [5].
- Population
- One trial within a systematic review [5].
- Sources
- [5]
- Caveats
- A 2016 search found no studies of IV glutathione for skin lightening and none of its safety in chronic use for any indication [6].
Doses studied
Oral studies used a single 3 g dose [1], 500 mg twice a day for 4 weeks [2], and 250 or 1,000 mg a day for 6 months [3]. Skin trials used 250 to 500 mg a day by mouth [4][5]. The chemotherapy trial gave 1,500 mg/m² IV over 15 minutes [7]. In the FDA case reports, patients received 1,400 mg or 2,400 mg IV [11].
Risks
Reported risks1
Reactions to contaminated IV glutathione
Case reports: 7 clinic patients had nausea, vomiting and chills minutes after compounded IV glutathione. FDA linked this to possible high endotoxin levels.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- Seven patients at an outpatient clinic received 1,400 mg of compounded IV glutathione. Within minutes they had nausea, vomiting, lightheadedness, chills, body aches and sneezing. One had low blood pressure and trouble breathing and went to hospital. FDA linked the reactions to possible high endotoxin levels in a dietary-supplement-grade powder, and in February 2019 warned compounders not to use it for injectables [11].
- Population
- 7 patients in one report, plus a second report from a different pharmacy [11].
- Sources
- [11]
- Caveats
- These are adverse event reports tied to specific lots, not trial data [11].
Checked, no increase found1
Side effects of oral glutathione
Limited evidence: short trials reported no or minimal side effects with oral glutathione.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- A review reported some nonserious adverse events in skin trials [4]. A 2016 review found most trials reported no or minimal side effects, over a few IV doses or 4 to 12 weeks oral [6]. In the hepatitis B trial, adverse reaction rates were 8.89% with glutathione and 20.00% without, a difference that was not significant [10].
- Population
- 4 studies [4]; trials across indications [6]; 90 patients with hepatitis B [10].
- Sources
- [4], [6], [10]
- Caveats
- Trials were short. The 2016 authors raise a hypothesis that a switch in melanin type could raise sun-induced skin cancer risk, which no study has tested [6].
Possible, not studied in people1
Long-term IV use
Not studied in people. No study has followed repeated IV use over time, and reviewers warn that shifting skin pigment toward red melanin could raise sun-related skin cancer risk.
No study in people. This rests on how it acts in the body.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- A 2016 review found that IV glutathione trials for any use lasted only a few doses, and that no study reported long-term IV use. Its authors note that the switch from brown to red melanin production that skin lightening relies on may increase the risk of sun-induced skin cancers [12]. A 2026 review lists hepatotoxicity, hypersensitivity reactions and possible kidney and hormone effects as safety concerns for IV glutathione and calls for prolonged safety studies [13].
- Population
- Reviews of published trials and reports [12][13].
- Sources
- [12], [13]
- Caveats
- The skin cancer concern is reasoned from melanin biology and has not been looked for in people who use IV glutathione [12]. The acute reactions in the block above came from single infusions, not long-term use.
Claims tested and not found
- That a dose of oral glutathione raises blood glutathione. A single 3 g dose did not raise plasma glutathione [1].
- That 4 weeks of oral glutathione lowers oxidative stress. Oxidative stress markers and glutathione status did not change [2].
- That glutathione improves Parkinson's symptoms. Intranasal glutathione did not significantly improve symptoms in a systematic review of 9 studies [9].
Sources
- Witschi A, Reddy S, Stofer B, et al. The systemic availability of oral glutathione. European Journal of Clinical Pharmacology. 1992. https://doi.org/10.1007/BF02284971
- Allen J, Bradley RD. Effects of Oral Glutathione Supplementation on Systemic Oxidative Stress Biomarkers in Human Volunteers. The Journal of Alternative and Complementary Medicine. 2011. https://doi.org/10.1089/acm.2010.0716
- Richie JP, Nichenametla S, Neidig W, et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. European Journal of Nutrition. 2015. https://doi.org/10.1007/s00394-014-0706-z
- Dilokthornsakul W, Dhippayom T, Dilokthornsakul P. The clinical effect of glutathione on skin color and other related skin conditions: A systematic review. Journal of Cosmetic Dermatology. 2019. https://doi.org/10.1111/jocd.12910
- Sarkar R, Yadav V, Yadav T, et al. Glutathione as a skin-lightening agent and in melasma: a systematic review. International Journal of Dermatology. 2025. https://doi.org/10.1111/ijd.17535
- Davids LM, Van Wyk JC, Khumalo NP. Intravenous glutathione for skin lightening: Inadequate safety data. South African Medical Journal. 2016. https://doi.org/10.7196/SAMJ.2016.v106i8.10878
- Cascinu S, Catalano V, Cordella L, et al. Neuroprotective Effect of Reduced Glutathione on Oxaliplatin-Based Chemotherapy in Advanced Colorectal Cancer: A Randomized, Double-Blind, Placebo-Controlled Trial. Journal of Clinical Oncology. 2002. https://doi.org/10.1200/JCO.2002.07.061
- Geum MJ, Jeon J, Moon J, et al. Evidence on Glutathione and Boosters for Prevention of Chemotherapy-Induced Neuropathy: A Systematic Review and Network Meta-Analysis. Basic & Clinical Pharmacology & Toxicology. 2026. https://doi.org/10.1111/bcpt.70319
- Mohammed I, Nankya Y, Hong UT, et al. The role of N-acetylcysteine and glutathione in the management of Parkinson's disease: a systematic review of oxidative biomarkers and clinical outcomes. Amino Acids. 2026. https://doi.org/10.1007/s00726-026-03513-5
- Wei Q, Zhao J. Therapeutic effects of reduced glutathione on liver function, fibrosis, and HBV DNA clearance in chronic hepatitis B patients. BMC Gastroenterology. 2025. https://doi.org/10.1186/s12876-025-03600-z
- US Food and Drug Administration. FDA highlights concerns with using dietary ingredient glutathione to compound sterile injectables. 2019. https://www.fda.gov/drugs/human-drug-compounding/fda-highlights-concerns-using-dietary-ingredient-glutathione-compound-sterile-injectables
- Davids LM, Van Wyk JC, Khumalo NP. Intravenous glutathione for skin lightening: inadequate safety data. South African Medical Journal. 2016. https://doi.org/10.7196/samj.2016.v106i8.10878
- 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. Journal of Medicine and Life. 2026. https://doi.org/10.25122/jml-2026-0054