Glutathione
GSH · L-glutathione · reduced glutathione
Oral 500 mg/day reduced the melanin index vs placebo in RCTs; IV use for skin lightening is not recommended
Overview
Glutathione is a tripeptide of glutamate, cysteine, and glycine and the body's principal intracellular antioxidant, central to redox balance, phase-II detoxification, and the recycling of other antioxidants such as vitamins C and E. Its single reactive thiol (the cysteine sulfur) donates an electron to neutralize reactive oxygen species, after which the oxidized form is regenerated by glutathione reductase. Plasma half-life of free GSH is short — on the order of 2–3 hours — which shapes how the various dosing routes are used.
Interest in glutathione for skin centers on pigmentation: it is proposed to inhibit tyrosinase and to shift melanin synthesis away from darker eumelanin toward lighter pheomelanin. The supporting human evidence is strongest for the oral route. Several randomized controlled trials of oral glutathione (250 mg once or twice daily, or 500 mg once daily) over 4–12 weeks have shown statistically significant — though modest — reductions in the melanin index versus placebo, with the effect reversing after the supplement is stopped. By contrast, the only placebo-controlled study of intravenous glutathione for lightening did not support routine use, and IV administration carries real risks (anaphylaxis, hepatotoxicity, and contamination in unregulated settings) without proven added benefit.
Routes differ substantially. Oral capsules (250–1,000 mg/day) and liposomal or sublingual products (~300–500 mg/day) are the supplement mainstays; bioavailability of plain oral GSH is debated, with some trials showing raised blood levels and others none. Intravenous dosing in clinics is typically 600–1,200 mg per session once or twice weekly. Intranasal/nebulized glutathione (around 300–600 mg) has been studied chiefly in pulmonary and neurological contexts rather than for skin. Subcutaneous and intramuscular use also occur in compounding practice. All figures here summarize published trials and reported clinical practice and are an educational research reference only — not medical advice, and not an endorsement of injectable use.
Key parameters
- Dose range
- 500 mg/day oral (RCT); 600–1,200 mg/session IV (clinic)
- Frequency
- Daily (oral) to 1–2× weekly (IV)
- Half-life
- ~2–3 hours (plasma GSH)
- Route
- Oral, IV, IM, SC, intranasal/nebulized
- Vial sizes
- 200 mg · 600 mg
- Regulatory status
- Glutathione is an endogenous tripeptide and a widely sold oral dietary supplement. No injectable glutathione product is FDA-approved for skin lightening or general wellness in the United States; injectable and nebulized forms are compounded or research-grade. The FDA issued a 2019 safety alert after patients reacted to an endotoxin-contaminated compounded injectable. Regional status varies.
Mechanism of action
Antioxidant / redox buffering
Acts as the major intracellular thiol antioxidant, donating an electron from its cysteine sulfur to neutralize reactive oxygen species and maintain cellular redox state, then being regenerated by glutathione reductase.
Detoxification (phase II conjugation)
Serves as the substrate for glutathione-S-transferases, conjugating reactive electrophiles, drugs, and other xenobiotics into water-soluble forms for elimination.
Tyrosinase inhibition and melanogenesis modulation
Proposed to inhibit tyrosinase and to steer melanin synthesis toward lighter pheomelanin rather than darker eumelanin — the rationale behind skin-lightening use, supported modestly by oral RCTs.
Regeneration of other antioxidants
Helps recycle oxidized vitamin C and vitamin E back to their active forms, extending the cell's overall antioxidant capacity beyond glutathione itself.
Dosing protocol & phases
| Phase | Weeks | Dose | Notes |
|---|---|---|---|
| Oral (supplement / RCT-supported) | 4–12 weeks (skin studies) | 250–1,000 mg/day; 500 mg/day used in lightening RCTs | Taken daily as a single or split dose; the melanin-index effect is modest and reverses on stopping. Liposomal/sublingual products use ~300–500 mg/day. |
| Intravenous (clinic-administered) | Per protocol (e.g. ~6 weeks) | 600–1,200 mg per session, 1–2× weekly | Reflects reported clinic practice, not an endorsed regimen; the controlled evidence for IV skin-lightening is weak and safety concerns are significant. |
| Intranasal / nebulized | Up to ~3 months (study settings) | ~300–600 mg/day, often split as a spray | Studied mainly for pulmonary and neurological indications (e.g. Parkinson's), where it was tolerated but did not clearly beat placebo — not a skin route. |
Reconstitution guide
For educational and research reference only. Not intended for human consumption, not medical advice. Compounds discussed are sold and used for laboratory research purposes only.
200 mg vial + 2 mL bacteriostatic water
Concentration100,000 mcg/mL · 100 mg/mL
| Target dose | Draw volume | U-100 units |
|---|---|---|
| 50,000 mcg | 0.5 mL | 50 |
| 100,000 mcg | 1 mL | 100 |
A 200 mg vial in 2 mL gives 100,000 mcg/mL (100 mg/mL). Because glutathione is dosed in tens-to-hundreds of milligrams, draws are large: 100 mg is a full 1.0 mL (100 units). Illustrative only — injectable dosing is not a validated or endorsed protocol.
600 mg vial + 3 mL bacteriostatic water
Concentration200,000 mcg/mL · 200 mg/mL
| Target dose | Draw volume | U-100 units |
|---|---|---|
| 100,000 mcg | 0.5 mL | 50 |
| 200,000 mcg | 1 mL | 100 |
A 600 mg vial in 3 mL gives 200,000 mcg/mL (200 mg/mL), so a 200 mg amount is 1.0 mL (100 units). Larger doses are typically diluted further into IV fluid by a clinician rather than drawn into an insulin syringe.
Reconstitution calculator
Pre-filled with Glutathione's vial sizes. Adjust the water volume and target dose to see the exact draw, with warnings for doses that are hard to measure or won't fit a syringe.
At 100,000 micrograms per millilitre, a 50,000 microgram dose is 0.5 millilitres, or 50 units on a U-100 syringe, giving 4 doses per vial.
Supplies needed
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Recommended supply
Glutathione — research vial
From our verified partner Dynotides, with a third-party certificate of analysis per batch.
Injection supplies
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Bacteriostatic water
Diluent for reconstituting lyophilized vials.
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Insulin syringes (U-100)
0.3–0.5 mL, 29–31 G for accurate small draws.
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Alcohol prep pads
Sterile swabs for the vial stopper and site.
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Sharps container
Safe disposal of used needles.
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Storage fridge
Keeps reconstituted vials at 2–8 °C.
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Insulated travel case
Cooled, TSA-friendly case for travel.
Missed-dose guidance
No approved-label schedule exists for injectable glutathione, so missed-dose handling is not standardized. For oral supplement use, simply resume the usual daily routine rather than doubling up; a single missed dose is not significant given the short half-life. For clinic-administered IV sessions, the missed session is typically rescheduled with the provider rather than made up by increasing a later dose.
Side effects & safety
| Category | Effect | Trial incidence |
|---|---|---|
| Gastrointestinal | Bloating, loose stools, or cramping (oral/liposomal)Generally mild and the most common complaints with oral use. | — |
| Gastrointestinal | Abdominal cramps (injectable)Reported in roughly 40% in some injectable case series. | 40% |
| Hepatic | Liver-enzyme abnormalities (injectable)Reported in about a third of an injectable case series; serious acute liver injury has appeared in case reports. | 32% |
| Immunologic | Anaphylaxis / serious hypersensitivity (injectable)Documented in case reports; a key reason IV glutathione for cosmetic use is discouraged. | — |
| Infectious | Contamination-related reactions in unregulated settingsEndotoxin or sterility failures are the primary danger with compounded injectables; the FDA's 2019 alert followed seven such reactions. | — |
| Dermatologic | Skin rash, and theoretical pigmentary changes with prolonged lightening useReported occasionally; long-term safety of sustained pigment suppression is not well established. | — |
Clinical trials & evidence
Oral glutathione skin-lightening RCTs (pooled)
Phase 2 / RCT4–12 weeks · Adults, predominantly Asian cohorts
Across several randomized, placebo-controlled trials, oral glutathione (250 mg once or twice daily, or 500 mg once daily) produced statistically significant but modest reductions in the melanin index in sun-exposed skin, with the effect reversing after discontinuation.
Trial identifier needs verification
Intravenous glutathione for skin lightening
Clinical (placebo-controlled, single study)Varies · Adults seeking skin lightening
The single placebo-controlled study did not establish efficacy, and reviews conclude IV glutathione is not recommended for lightening given the lack of proven benefit and documented risks (anaphylaxis, hepatotoxicity).
Trial identifier needs verification
Oral glutathione in non-alcoholic fatty liver disease (pilot)
Pilot / small trials~4 months · Adults with NAFLD (one pilot of ~300 mg/day; pooled review ~109 participants)
Reported reductions in ALT and oxidative-stress markers, suggesting an antioxidant effect, though the trials were small and not skin-focused.
Trial identifier needs verification
Storage & handling
- Lyophilized
- Store lyophilized or powdered glutathione cold (2–8 °C) and protected from light; −20 °C is used for long-term storage. The powder is white to off-white.
- Reconstituted
- Refrigerate the reconstituted solution at 2–8 °C, protected from light, and use promptly — glutathione oxidizes readily, so stability is limited. The solution should be clear; discard if it turns cloudy or discolored, and do not freeze.
Comparisons
| Vs. | Target | Half-life | Dosing | Efficacy | Status |
|---|---|---|---|---|---|
| NAC (N-acetylcysteine) | Antioxidant thiol vs cysteine precursor that feeds GSH synthesis | ~2–3 h vs ~6 h | Oral 250–1,000 mg/day or IV vs oral/IV in gram amounts | Direct antioxidant vs precursor; NAC is the recognized antidote for acetaminophen overdose | Supplement orally / not approved injectable for skin vs FDA-approved drug (acetaminophen toxicity) |
| NAD | Antioxidant thiol vs NAD+ precursor/cofactor for cellular metabolism | ~2–3 h vs route-dependent | Route-dependent (oral mainstay) vs route-dependent | Redox/pigmentation focus vs energy-metabolism and longevity focus | Both not approved drugs for these uses |
Sources & references
- [1]Sarkar R et al. Glutathione as a skin-lightening agent and in melasma: a systematic review. Int J Dermatol 2025. ↗ source
- [2]Wahab S et al. Combination of topical and oral glutathione as a skin-whitening agent: a double-blind RCT. Int J Dermatol 2021. ↗ source
- [3]FDA. Drug Safety Alert — adverse events from compounded injectable glutathione (2019). ↗ source
Frequently asked questions
Does glutathione actually lighten skin?
The best evidence is for the oral route: randomized placebo-controlled trials of about 250–500 mg/day for 4–12 weeks have shown modest, statistically significant drops in the melanin index, but the effect is small and reverses once you stop. Intravenous glutathione for lightening is not supported by good controlled evidence and is discouraged because of safety risks.
Why is injectable glutathione considered risky?
Beyond the weak efficacy data, injectable glutathione has been linked to anaphylaxis, liver injury, and — most importantly in unregulated settings — contamination. The FDA issued a 2019 alert after seven patients reacted to an endotoxin-contaminated compounded product. No injectable glutathione is FDA-approved for skin lightening or wellness.
Is glutathione a peptide?
Yes — it is a tripeptide of glutamate, cysteine, and glycine and the body's main intracellular antioxidant. It is included in the skin category for its aesthetic-research use, principally the pigmentation claims.
How is glutathione different from NAC?
NAC (N-acetylcysteine) is a precursor that supplies cysteine, the rate-limiting building block for the body to make its own glutathione — it is not glutathione itself. Some people use NAC to raise glutathione indirectly; unlike cosmetic glutathione, NAC is an FDA-recognized drug used as the antidote for acetaminophen overdose.
Related protocols
NAD+
Nicotinamide adenine dinucleotide
Central redox coenzyme; declines with age (mechanistic interest)
GHK-Cu
Copper tripeptide-1
Endogenous copper-binding tripeptide that declines with age
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For educational and research reference only. Not intended for human consumption, not medical advice. Compounds discussed are sold and used for laboratory research purposes only.