Peptides & growth hormone

Glutathione

Updated · 22 sources · Editorial policy

Glutathione is a small molecule made of three amino acids (glutamate, cysteine and glycine) that the body’s cells make themselves. It is present in all mammalian tissues as the most abundant non-protein thiol and a central part of the body’s defense against oxidative stress and of the detoxification of drugs and toxins (Lu, Biochim Biophys Acta 2013).

It is sold as an oral dietary supplement and as compounded injections, mostly marketed for skin lightening, “detox” and general wellness. Glutathione is not a component of any FDA-approved drug. In 2019 and again in August 2026, the FDA warned that injectable glutathione compounded from dietary-supplement-grade powder had been linked to adverse events consistent with bacterial endotoxin contamination (FDA, 2026).

This page summarizes what the pharmacokinetic studies, clinical trials and FDA report. It is for education only and is not medical advice.

Property Detail
Class Endogenous tripeptide (γ-glutamyl-cysteinyl-glycine); thiol antioxidant
Formula / weight C₁₀H₁₇N₃O₆S, 307.33 g/mol (PubChem)
Forms Reduced (GSH) and oxidized (GSSG); oral capsules, liposomal and sublingual products, topical, inhaled, compounded IV
Studied doses Oral 250–1,000 mg/day; IV 1,400 mg three times weekly (Parkinson’s pilot); inhaled 646 mg twice daily (cystic fibrosis)
Half-life (IV) ≈14 min (14.1 ± 9.2 min) after a 2 g/m² infusion in healthy volunteers
Oral uptake A single 3 g dose did not raise blood levels; 6 months of daily dosing raised blood-compartment levels by 17–35%
US status Sold as a dietary supplement; not a component of any FDA-approved drug; FDA proposed not adding it to the 503A compounding bulks list (2022)
WADA status Not named on the 2026 list; IV infusions over 100 mL per 12 hours are a prohibited method (M2.2)

What it is

Glutathione is a tripeptide with an unusual bond: glutamate is linked to cysteine through its side-chain (gamma) carboxyl group rather than the usual alpha position (PubChem). Its active part is the sulfur-containing thiol group of cysteine. The reduced form (GSH) is the active antioxidant; the oxidized form (GSSG) is two molecules joined at their sulfur atoms. Trials use a falling oxidized-to-reduced glutathione ratio as a sign of lower oxidative stress (Richie et al., Eur J Nutr 2015).

Cells build glutathione in two steps (Lu, Biochim Biophys Acta 2013):

Step Enzyme Key point
1. Glutamate + cysteine Glutamate cysteine ligase (GCL) The rate-limiting step
2. Add glycine Glutathione synthetase (GS) Completes the tripeptide

The supply of cysteine is the other main limit on how much glutathione cells can make. This is the rationale for cysteine donors such as NAC (N-acetylcysteine), which raise glutathione indirectly by supplying its building block. Beyond antioxidant defense, glutathione is involved in detoxifying foreign chemicals, redox signaling and immune function.

Skin-lightening mechanism

The claimed skin effect rests on laboratory work showing that glutathione inhibits tyrosinase, the key enzyme of melanin production, and shifts pigment production from dark eumelanin toward lighter pheomelanin (Sonthalia et al., Indian J Dermatol Venereol Leprol 2016).

Pharmacokinetics

Intravenous

The main human kinetic study gave 10 healthy volunteers an IV infusion of 2 g/m² of glutathione (Aebi et al., Eur J Clin Invest 1991):

Measure Result
Plasma total glutathione 17.5 → 823 µmol/L
Volume of distribution 176 ± 107 mL/kg
Elimination half-life 14.1 ± 9.2 min
Plasma cysteine 8.9 → 114 µmol/L
Urinary glutathione excretion (90 min) Increased ≈300-fold

Infused glutathione is therefore cleared from the blood within minutes. Although free cysteine rose, total plasma cyst(e)ine fell, which the authors interpreted as increased uptake of cysteine into cells.

Oral

Oral glutathione is broken down in the gut and liver by the enzyme gamma-glutamyltransferase. In 7 healthy volunteers, a single oral dose of 0.15 mmol/kg (about 3 g) did not significantly raise plasma glutathione, cysteine or glutamate over 270 minutes. The authors concluded that the systemic availability of a single dose was negligible (Witschi et al., Eur J Clin Pharmacol 1992).

Longer daily dosing gave a different result. In a 6-month randomized, double-blind, placebo-controlled trial in 54 non-smoking adults (Richie et al., Eur J Nutr 2015):

Dose Change in glutathione at 6 months vs baseline
250 mg/day +17% whole blood; +29% red blood cells
1,000 mg/day +30–35% in red blood cells, plasma and lymphocytes; +260% in cheek (buccal) cells

Levels returned to baseline after a 1-month washout. Natural killer cell activity more than doubled versus placebo at 3 months in the high-dose group.

Other delivery forms have been tested in small studies:

  • Liposomal: In a 1-month pilot in 12 healthy adults taking 500 or 1,000 mg/day, blood glutathione rose by up to 40% in whole blood and 100% in peripheral blood mononuclear cells by week 2. The study was funded by the maker of the product, and the authors noted limited statistical power (Sinha et al., Eur J Clin Nutr 2018).
  • Sublingual: In a 3-week crossover study of 20 people with metabolic syndrome, a sublingual form raised plasma glutathione and the GSH:GSSG ratio more than oral glutathione. The authors reported it as superior to both oral glutathione and NAC; two of the four authors were affiliated with a commercial laboratory, Laboratoires Le Stum (Schmitt et al., Redox Biol 2015).

Regulatory status

Glutathione is not an FDA-approved drug. In the US it is marketed as a dietary supplement ingredient (FDA, 2019). FDA states that dietary-supplement-grade glutathione is not an appropriate ingredient for making injectable drugs (FDA, 2026).

Pharmacies compound injectable glutathione from bulk powder. In June 2022, the FDA’s Pharmacy Compounding Advisory Committee reviewed whether glutathione should be added to the 503A bulks list of substances that may be used in compounding. FDA proposed that it not be included. The committee voted 8 to 5 (1 abstention) in favor of adding it; the vote is advisory. Members voting no cited a lack of evidence of effectiveness for the conditions reviewed (FDA PCAC minutes, 2022). The uses FDA evaluated ranged from skin lightening and cystic fibrosis to Parkinson’s disease, autism and septic shock.

Glutathione is not named on the WADA Prohibited List. However, intravenous infusions or injections of more than 100 mL in a 12-hour period are a prohibited method (M2.2) outside of legitimate hospital treatment, surgery or clinical investigations, regardless of what is infused (WADA 2026 Prohibited List).

What the research shows

Skin lightening

Most controlled human data come from small trials in healthy Asian volunteers:

Trial Design Dose and duration Result
Arjinpathana 2012 RCT, 60 medical students Oral 500 mg/day, 4 weeks Melanin index fell at all 6 sites; significantly more than placebo at 2 sites (right face p = 0.021; sun-exposed forearm p = 0.036)
Weschawalit 2017 RCT, 3 arms, healthy women Oral GSH 250 mg/day, GSSG 250 mg/day, or placebo, 12 weeks Melanin index and UV spots tended to be lower than placebo; some wrinkle sites improved with GSH

A 2025 systematic review found that five randomized trials of oral glutathione (250–500 mg/day) reported reductions in the melanin index versus placebo. It found only one placebo-controlled trial of IV glutathione, in which 6 of 16 (37.5%) versus 3 of 16 (18.7%) responded, a difference that was not statistically significant (p = 0.054). The review judged that the lightening from oral and topical forms is moderate and not sustained, and that IV glutathione should not be used because of lack of efficacy and side effects (Sarkar et al., Int J Dermatol 2025).

Parkinson’s disease

Glutathione is depleted early in the course of Parkinson’s disease, which led to trials of direct supplementation:

  • IV: A randomized, double-blind pilot gave 21 patients 1,400 mg IV or placebo three times a week for 4 weeks. Changes in UPDRS scores (the standard Parkinson’s rating scale) did not differ significantly between groups (p = 0.32), and the treatment was well tolerated (Hauser et al., Mov Disord 2009).
  • Intranasal: A phase IIb trial randomized 45 patients to placebo, 100 mg or 200 mg intranasal glutathione three times daily for 3 months. All groups improved, including placebo, and neither dose was superior to placebo. One participant in the high-dose group developed cardiomyopathy (Mischley et al., J Parkinsons Dis 2017).

Chemotherapy-induced nerve damage

In a double-blind trial in 50 patients with advanced gastric cancer receiving weekly cisplatin, glutathione (1.5 g/m² IV before each cisplatin dose, then 600 mg IM on days 2–5) was compared with placebo. After 15 weeks, neuropathy occurred in 4 of 24 assessable patients on glutathione versus 16 of 18 on placebo (p = 0.0001), with no apparent loss of tumor response (Cascinu et al., J Clin Oncol 1995).

A Cochrane review pooled seven glutathione trials (387 participants). On non-quantitative toxicity grading, glutathione reduced the risk of grade 2 or higher neuropathy (RR 0.29, 95% CI 0.10–0.85). But the reviewers concluded that the data were insufficient to show that glutathione, or any other agent studied, prevents platinum neurotoxicity when measured with objective tests (Albers et al., Cochrane 2014).

Cystic fibrosis

In a 6-month randomized, double-blind trial in 153 people with cystic fibrosis aged 8 and older, inhaled glutathione (646 mg every 12 hours) did not improve lung function (FEV₁), the primary endpoint. It also did not reduce exacerbations or improve quality of life, and markers of oxidative stress and inflammation did not change even though glutathione reached the airways (Griese et al., Am J Respir Crit Care Med 2013).

Exercise

Evidence in athletes is minimal. In a crossover study, 8 healthy men took 1 g/day of oral glutathione or placebo for 2 weeks before 60 minutes of cycling at 40% of maximal heart rate. Blood lactate after exercise was lower with glutathione (2.9 vs 3.4 mM), and fatigue ratings improved. Two authors were affiliated with a company (KOHJIN Life Sciences), and there are no larger trials on performance, muscle mass or recovery (Aoi et al., J Int Soc Sports Nutr 2015).

Side effects and risks

Oral

Oral glutathione was well tolerated in the trials above, at 250–1,000 mg/day for up to 6 months (Richie et al., Eur J Nutr 2015; Arjinpathana 2012). Long-term safety beyond that has not been studied.

Contaminated compounded injections

The main documented hazard is contaminated injectable product, not glutathione itself:

  • 2019: FDA received reports of seven patients at one clinic who developed nausea, vomiting, lightheadedness, chills and body aches within minutes of receiving 1,400 mg IV glutathione; one with low blood pressure and difficulty breathing was transferred to a hospital. A second patient was admitted with chills, fever and shaking after a 2,400 mg dose. FDA testing found endotoxin as high as five times the appropriate limit. The powder, repackaged by Letco Medical, had been labeled as a dietary supplement (FDA, 2019).
  • 2026: FDA reported at least 30 patients with adverse events after IV glutathione, alone or in combinations, compounded by different pharmacies that all used one lot of dietary-supplement-grade glutathione from Medisca. Reported events included fever, chills, pain, dizziness, signs of shock and sepsis-like symptoms, some requiring hospitalization. Two Texas pharmacies recalled glutathione injectables over elevated endotoxin levels (FDA, 2026).

Endotoxin (a toxic component of bacterial cell walls) can cause fever, chills, nausea, low blood pressure, shock and death when injected (FDA, 2019).

IV use for skin lightening

Reviews describe a gap between the popularity of IV glutathione for skin lightening and the evidence for it. The Food and Drug Administration of the Philippines issued a public warning against IV glutathione for off-label uses such as skin lightening, citing its adverse effects (Sonthalia et al., Indian J Dermatol Venereol Leprol 2016). A 2025 systematic review concluded that IV glutathione should not be used for this purpose (Sarkar et al., Int J Dermatol 2025).

Inhaled glutathione and asthma

In a randomized crossover study of 8 patients with mild asthma, nebulized glutathione (600 mg) caused marked airway narrowing: FEV₁ fell 19% versus 1% with placebo, and some patients developed cough or breathlessness. The authors attributed this to sulfite formation (Marrades et al., Am J Respir Crit Care Med 1997). In the larger cystic fibrosis trial, adverse events were similar with glutathione and placebo (Griese et al., 2013).

Key takeaways

  • The body makes its own. Glutathione is made inside cells, and its production depends mainly on cysteine supply and the enzyme glutamate cysteine ligase.
  • Oral uptake is limited but not zero. A single 3 g dose did not raise blood levels, but 6 months of 250–1,000 mg/day raised blood levels by about 17–35%, and levels fell back after stopping.
  • IV glutathione is cleared in minutes. The measured half-life was about 14 minutes.
  • Clinical benefits are unproven. Trials in Parkinson’s disease and cystic fibrosis were negative or inconclusive; evidence for preventing chemotherapy nerve damage is not considered sufficient; oral skin lightening is modest and temporary.
  • Not an approved drug. It is sold as a supplement, and FDA proposed not adding it to the compounding bulks list.
  • Injectable products carry real contamination risk. FDA linked IV glutathione made from supplement-grade powder to endotoxin reactions in 2019 and in at least 30 patients in 2026.

Sources

  1. National Center for Biotechnology Information. PubChem Compound Summary for CID 124886, Glutathione. PubChem.
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  4. Witschi A, Reddy S, Stofer B, Lauterburg BH. The systemic availability of oral glutathione. Eur J Clin Pharmacol. 1992;43(6):667–669. PubMed.
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  6. Sinha R, Sinha I, Calcagnotto A, et al. Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function. Eur J Clin Nutr. 2018;72(1):105–111. PubMed.
  7. Schmitt B, Vicenzi M, Garrel C, Denis FM. Effects of N-acetylcysteine, oral glutathione (GSH) and a novel sublingual form of GSH on oxidative stress markers: A comparative crossover study. Redox Biol. 2015;6:198–205. PubMed.
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  9. 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. PubMed.
  10. Weschawalit S, Thongthip S, Phutrakool P, Asawanonda P. Glutathione and its antiaging and antimelanogenic effects. Clin Cosmet Investig Dermatol. 2017;10:147–153. PubMed.
  11. Sarkar R, Yadav V, Yadav T, et al. Glutathione as a skin-lightening agent and in melasma: a systematic review. Int J Dermatol. 2025;64(6):992–1004. PubMed.
  12. Hauser RA, Lyons KE, McClain T, et al. Randomized, double-blind, pilot evaluation of intravenous glutathione in Parkinson’s disease. Mov Disord. 2009;24(7):979–983. PubMed.
  13. Mischley LK, Lau RC, Shankland EG, et al. Phase IIb Study of Intranasal Glutathione in Parkinson’s Disease. J Parkinsons Dis. 2017;7(2):289–299. PubMed.
  14. Cascinu S, Cordella L, Del Ferro E, et al. Neuroprotective effect of reduced glutathione on cisplatin-based chemotherapy in advanced gastric cancer: a randomized double-blind placebo-controlled trial. J Clin Oncol. 1995;13(1):26–32. PubMed.
  15. Albers JW, Chaudhry V, Cavaletti G, Donehower RC. Interventions for preventing neuropathy caused by cisplatin and related compounds. Cochrane Database Syst Rev. 2014;(3):CD005228. PubMed.
  16. Griese M, Kappler M, Eismann C, et al. Inhalation treatment with glutathione in patients with cystic fibrosis. A randomized clinical trial. Am J Respir Crit Care Med. 2013;188(1):83–89. PubMed.
  17. Marrades RM, Roca J, Barberà JA, et al. Nebulized glutathione induces bronchoconstriction in patients with mild asthma. Am J Respir Crit Care Med. 1997;156(2 Pt 1):425–430. PubMed.
  18. Aoi W, Ogaya Y, Takami M, et al. Glutathione supplementation suppresses muscle fatigue induced by prolonged exercise via improved aerobic metabolism. J Int Soc Sports Nutr. 2015;12:7. PubMed.
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  20. Food and Drug Administration. FDA highlights concerns with using dietary ingredient glutathione to compound sterile injectables. June 7, 2019. FDA.
  21. Food and Drug Administration. FDA reminds compounders not to use dietary supplement grade glutathione for injectables. August 27, 2026. FDA.
  22. World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA 2026 Prohibited List.