About Glutathione
Glutathione is a tripeptide of glutamate, cysteine, and glycine that serves as the body's primary intracellular antioxidant. Supplementation is studied for liver detoxification, oxidative stress, and skin pigmentation.
Longevity
Glutathione
Master Antioxidant Tripeptide
A tripeptide antioxidant studied for cellular detoxification and skin brightening.
Early humanResearch use only
Where to buy
Vendor offerings
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Best $/mg
S1 ResearchTestedGlutathione 1500mg(1482.36mg)
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$0.053/mg · 1500mg
Solution PeptidesTestedGlutathione – 1500mg
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Atomik LabzTestedLIQUID – Glutathione 200mg per ml (20ml)
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Evidence level
Early human studies
A tripeptide of glutamate, cysteine, and glycine that is the body's primary intracellular antioxidant. Exogenous supplementation is studied for liver detoxification, oxidative stress, and skin pigmentation, with mixed evidence depending on route.
Mechanism
Donates electrons to neutralize reactive oxygen species and regenerates other antioxidants.
Researched benefits
Replenishment of intracellular antioxidant pool
Glutathione (GSH) directly neutralizes reactive oxygen species and regenerates oxidized vitamins C and E. Tissue GSH declines with age and in chronic disease; IV and liposomal oral routes have shown measurable increases in plasma and red blood cell GSH.
Skin lightening
Multiple small randomized trials (most in Southeast Asian populations) show reductions in melanin index and skin lightening with oral or IV glutathione over 4–12 weeks. The effect is mediated by inhibition of tyrosinase and a shift from eumelanin to pheomelanin synthesis.
Hepatic detoxification support
GSH is the cofactor for glutathione-S-transferase conjugation, the major phase II detoxification pathway. N-acetylcysteine (NAC), a GSH precursor, is the established treatment for acetaminophen overdose — confirming the clinical relevance of replenishing this system.
Possible benefit in Parkinson's disease (early signal)
Small trials of IV and intranasal glutathione in Parkinson's have shown short-term symptomatic improvements, but a 2017 randomized trial (n=45) did not show benefit over placebo on UPDRS scores. The evidence is mixed.
Risks & cautions
- moderate
Unwanted depigmentation
The skin-lightening effect is dose- and duration-dependent and may be uneven. Some users develop visible patches of lighter skin or unwanted overall pallor. Philippine health authorities have issued warnings about high-dose IV glutathione for cosmetic use.
- moderate
IV-route adverse events
Case reports of Stevens-Johnson syndrome, toxic epidermal necrolysis, and severe hepatic events have been linked to high-dose cosmetic IV glutathione, particularly with compounded or unregulated preparations. Sterility of the preparation matters.
- low
Sulfur-related side effects
Sulfurous taste, mild GI upset, and odorous breath/urine are common with high oral doses. Liposomal formulations reduce GI symptoms.
- moderate
Asthma exacerbation (inhaled route)
Nebulized glutathione has triggered bronchospasm in some asthmatic patients. The inhaled route should be avoided in reactive airway disease.
Dosing
200–600 mg subcutaneous or IV, 1–3× per week. Oral liposomal preparations dose 500–1000 mg daily.
- Conservative
- 200 mg SC, 2×/week
- Standard
- 600 mg SC or IV, 2×/week
- Aggressive
- 1200 mg IV weekly (cosmetic protocols)
Vial sizes
200mg / 600mg / 1200mg
Half-life
Short
Route
subcutaneous, intravenous, oral
Plasma half-life of reduced glutathione is short (minutes). The relevant pharmacokinetic question is intracellular GSH recovery, which lags plasma. Oral non-liposomal glutathione is largely degraded in the gut; NAC or liposomal forms are preferred for oral routes.
Contraindications
- Active asthma if using the nebulized route
- Hypersensitivity to sulfur compounds
- Cosmetic use during pregnancy (no safety data)
In depth
Background
Glutathione is the most abundant intracellular thiol antioxidant. It exists in two forms — reduced (GSH) and oxidized (GSSG) — and the ratio between them is one of the best-validated cellular markers of oxidative stress. Every nucleated cell synthesizes its own glutathione; the rate-limiting substrate is cysteine.
It is not a "discovered" peptide in the way pharmaceutical peptides are — it has been known biochemically since the early 20th century. What is newer is its use as an injectable or oral supplement at supraphysiologic doses for skin, liver, and longevity indications.
Mechanism in depth
GSH functions through several distinct biochemical roles:
- Direct ROS scavenging — donates a hydrogen atom from the cysteine thiol to neutralize free radicals, becoming GSSG. Glutathione reductase regenerates GSH from GSSG using NADPH.
- Phase II conjugation — glutathione-S-transferases (GSTs) conjugate GSH to electrophilic xenobiotics for renal/biliary excretion.
- Redox signaling — the GSH/GSSG ratio modulates the activity of redox-sensitive transcription factors including Nrf2, NF-κB, and AP-1.
- Tyrosinase inhibition — the basis of the skin-lightening effect. GSH interferes with copper at tyrosinase's active site and shifts melanogenesis from eumelanin (dark) to pheomelanin (light).
Human evidence
Better-established than most peptides in this catalog, though indication-specific:
- Skin lightening: multiple small RCTs in Asian populations support a measurable effect on melanin index, with oral, IV, and topical routes all showing some activity.
- Oral supplementation and tissue GSH: a 2015 RCT (Richie et al., n=54) showed dose-dependent increases in body GSH stores after 6 months of oral dosing, modestly answering the long-running debate about oral bioavailability.
- Parkinson's disease: open-label trials suggested benefit; the only randomized trial was negative.
- NAFLD and liver disease: small trials with IV glutathione have shown improvements in liver enzymes, but evidence is preliminary.
Animal evidence
Foundational rather than novel — GSH biology in animals is so well-established that animal data is mostly used to validate biochemical mechanism rather than therapeutic claims. Models of acetaminophen toxicity, ischemia-reperfusion injury, and aging consistently show GSH depletion and benefit from precursor (NAC) repletion.
Stack synergy
Common pairings:
- NAD+ / NMN — both target redox/metabolic pathways; GSH protects mitochondria during NAD-driven metabolic upregulation.
- Vitamin C — IV vitamin C and IV glutathione are sometimes co-administered in "anti-aging" infusions; biochemically the two regenerate each other.
- Alpha-lipoic acid — recycles oxidized glutathione and vitamin C; rational pairing.
- NAC (N-acetylcysteine) — the cheaper oral precursor; for cost-conscious protocols, NAC plus glycine is a defensible alternative to direct GSH supplementation.
No major pharmacological conflicts. Caution with chemotherapy regimens that intentionally rely on oxidative stress (some platinum agents) — discuss with oncology.
Open questions
- Does long-term high-dose glutathione supplementation alter endogenous GSH synthesis through feedback?
- What is the best route for systemic effect — IV, liposomal oral, or sublingual?
- Is the skin-lightening effect cosmetically desirable in non-Asian skin types, or does it produce uneven pigmentation?
- Does chronic high-dose GSH have any effect on healthspan markers in humans? No long-term data exists.
References
- 1.Sechi G. et al. — Reduced intravenous glutathione in the treatment of early Parkinson's disease (Progress in Neuro-Psychopharmacology, 1996)
- 2.Sonthalia S. et al. — Glutathione as a skin whitening agent: facts, myths, evidence and controversies (Indian J Dermatol Venereol Leprol, 2016)
- 3.Richie J.P. et al. — Randomized controlled trial of oral glutathione supplementation on body stores (Eur J Nutr, 2015)