Established central role in antioxidant defence and detoxification [1]
Not in dispute at any level. Glutathione depletion is a recognised feature of oxidative stress, liver disease and numerous pathological states.
PrecisePep/Peptide Library/Glutathione
Immune & Anti-Inflammatory
Glutathione
GSH · γ-glutamyl-cysteinyl-glycine · reduced glutathione
The master antioxidant — a tripeptide every cell already synthesises for itself, sold for injection despite an oral precursor being cheaper, better studied and arguably more effective at raising it.
00 Overview
Glutathione is a tripeptide, so it belongs in a peptide library — but it is not a signalling peptide. It is a workhorse: the principal intracellular antioxidant, the substrate for glutathione peroxidase and glutathione S-transferase, and the molecule that conjugates electrophilic xenobiotics in Phase II hepatic detoxification. Every cell makes its own, and synthesis is rate-limited by cysteine availability.
That last fact is the crux of the whole page. Because cysteine is the bottleneck, the best-evidenced way to raise intracellular glutathione is to supply cysteine — which is what N-acetylcysteine does, orally, cheaply, with decades of clinical use including as the standard antidote for paracetamol overdose.[1]
Oral glutathione itself is largely hydrolysed in the gut, which is the argument for injecting it. It is also widely used — particularly in parts of Asia — for skin lightening, a use that has attracted explicit regulator warnings about unapproved injectable products.[3]
The precursor argument
If the goal is more intracellular glutathione, supplying the rate-limiting substrate is the mechanistically direct route, and NAC has far more human data behind it than injected GSH does. That is not an argument against glutathione being important — it is settled that it is — but against injection being the sensible way to get more of it.
// Mechanism of action
Redox buffering. The GSH/GSSG couple is the principal intracellular redox buffer, neutralising peroxides and reactive oxygen species via glutathione peroxidase.
Phase II conjugation. Glutathione S-transferases conjugate glutathione to electrophilic compounds — drug metabolites, environmental toxins, reactive intermediates — making them water-soluble and excretable. This is the "detoxification" claim, and here it is literal rather than metaphorical.
Cysteine as the bottleneck. Synthesis proceeds via γ-glutamylcysteine synthetase, and cysteine availability limits the rate. Supplying cysteine raises glutathione; supplying glutathione orally largely just supplies its constituent amino acids after hydrolysis.
Melanogenesis inhibition. Glutathione interferes with tyrosinase and shifts melanin synthesis from eumelanin toward the lighter phaeomelanin — the basis of the skin-lightening use.
Immune function. Lymphocyte function is glutathione-dependent, which is the basis for its inclusion in immune-support protocols.
01 Reported benefits
Effects that have been reported. A study-tier entry means a result was published — not that the effect is established, reproducible, or transferable from a rodent to a person.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
NAC reliably raises glutathione and is clinically established [1]
N-acetylcysteine is the standard treatment for paracetamol overdose precisely because it replenishes hepatic glutathione, and it has extensive additional trial literature.
Oral glutathione bioavailability is poor [2]
Hydrolysed by intestinal γ-glutamyltransferase. Some trials of sustained oral or liposomal forms report increased body stores, but the effect is inconsistent across studies.
Skin lightening effect demonstrated [3]
Human studies report reduced melanin index with oral and topical glutathione — the effect is real, which is why the practice is widespread.
Regulator warnings on injectable skin-lightening use [3]
The FDA and several national regulators have issued warnings about unapproved injectable glutathione products marketed for skin lightening, citing safety and sterility concerns.
Limited evidence for injected glutathione in healthy adults [4]
Parkinson disease and cystic fibrosis have seen small trials; general wellness use in healthy adults has essentially none.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
General antioxidant and detoxification support
The dominant use case. Coherent given the biochemistry and unestablished as an intervention in people who are not depleted.
Skin brightening and pigmentation reduction
The best-supported specific effect, and the one carrying regulator warnings when injected.
Supporting immune function
Lymphocyte function is glutathione-dependent, which is the rationale for the immune pillar placement.
Hepatic support during high compound loads
The reason it appears alongside multi-compound protocols. Mechanistically motivated by Phase II conjugation.
Concern: antioxidants can blunt adaptation
High-dose antioxidant supplementation has been shown in some studies to blunt exercise-induced adaptations, because reactive oxygen species are also signalling molecules. The same mitohormesis argument that applies to SS-31.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
Brighter, more even skin tone
The most consistent report, over weeks to months, and the one with the best supporting evidence.
Improved energy and reduced brain fog
Widely reported after IV administration. Same expectation-effect caveats as any clinic infusion.
Reduced hangover severity
A frequent use, and mechanistically plausible via acetaldehyde conjugation.
Sulphurous smell and taste
Reported with injection, unsurprising for a cysteine-containing tripeptide.
NAC reported as similarly effective and far cheaper
A counter-report that aligns with the evidence.
02 Adverse effects & risks
Adverse effects, contraindications and unknowns. The grey-market tier is where under-reporting is worst: uncontrolled use produces no systematic safety surveillance at all, so absence of a reported harm is not evidence of safety.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
Generally well tolerated [2]
Both oral and parenteral forms report good tolerability in studies at typical doses.
Regulator warnings on unapproved injectables [3]
Warnings cite sterility, contamination and unknown safety for injectable skin-lightening products specifically.
Reports of serious adverse events with IV skin-lightening use [3]
Including Stevens-Johnson syndrome, thyroid dysfunction, renal and hepatic effects reported in association with high-dose injectable use in the aesthetic context.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
Blunting of hormetic adaptation
Chronic high-dose antioxidant exposure may reduce the adaptive signalling that drives training benefit.
Asthma exacerbation with nebulised use
Inhaled sulphydryl compounds can provoke bronchospasm — relevant given nebulised use is common in community practice.
Sterility risk with self-administered IV
Intravenous self-administration of a non-sterile-filled product is among the higher-risk practices documented anywhere on this site.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
Injection-site stinging
Commonly reported with subcutaneous use.
Sulphur smell
Frequently reported.
Few systemic complaints
The adverse-effect column is quiet at community doses.
03 Dosing ranges
Figures below are documented, not recommended. Study ranges come from published protocols in the stated model; grey-market ranges are what the research community reports using and carry no safety validation of any kind.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
Oral and liposomal trial dosing [2]
Human studies have used several hundred milligrams to around a gram daily over weeks to months, with variable effects on measured glutathione stores.
NAC clinical dosing [1]
Well established across indications, and the better-characterised route to raising glutathione.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
Supply the precursor rather than the product
NAC is oral, inexpensive, clinically established and addresses the rate-limiting step directly.
Avoid self-administered IV
The risk is the route, not the molecule.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
IV: 600–2400 mg per session
Typical clinic infusion range, often weekly.
Subcutaneous: 100–300 mg daily
The common at-home community approach, and the reason 1200 mg vials are stocked alongside peptides. At 200 mg daily a 1200 mg vial is six days.
Subcutaneous doses are a fraction of IV doses
Injection volume limits subcutaneous dosing to the low hundreds of milligrams, against 600–2400 mg by infusion. Anyone reasoning from clinic infusion figures to a subcutaneous dose is out by roughly an order of magnitude.
Oral liposomal: 500–1000 mg daily
The practical oral route, better absorbed than plain oral glutathione.
| Route | Dose | Frequency | Notes |
|---|---|---|---|
| IV infusion | 600 – 2400 mg | Weekly | Clinic setting; regulator warnings apply |
| Subcutaneous | 100 – 300 mg | Daily | Stinging commonly reported |
| Oral liposomal | 500 – 1000 mg | Daily | Better absorbed than plain oral |
| NAC (precursor) | 600 – 1800 mg | Daily | Best clinical evidence, lowest cost |
04 Synergy & interactions
Combination effects. Almost no peptide combination has been studied as a combination in humans; stack logic is overwhelmingly mechanistic inference and community practice. Each linked compound has its own page.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
NAC plus glycine raises glutathione in older adults [4]
Combined supplementation of both rate-limiting precursors has been studied in older adults with reported improvements in glutathione status and several ageing markers.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
With Thymosin Alpha-1 in the immune pillar
Grouped together in the 15-Compound Matrix immune and detoxification matrix — complementary in framing rather than by demonstrated interaction.
With vitamin C
Vitamin C regenerates oxidised glutathione, a genuine biochemical relationship and the reason the two are often infused together.
Possible antagonism with hormetic interventions
Exercise adaptation, and arguably mitochondrial stress signalling, depend on reactive oxygen species. Suppressing them broadly may work against the goal.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
Immune and detoxification pillar of the 15-Compound Matrix
Paired with Thymosin Alpha-1.
Combined with vitamin C infusions
Standard clinic pairing.
05 Protocols
Whole schedules — dosing, titration, cycle length, and off-time — as documented in trials, as proposed from mechanism, and as circulated in the research community. Reproduced for study and comparison only.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
NAC in paracetamol overdose [1]
A defined, established clinical protocol built entirely on glutathione repletion — the strongest demonstration that the pathway matters.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
Precursor first, oral, cheap
The route with the evidence and none of the sterility risk.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
Weekly IV or daily oral
The two common patterns.
15-Compound Matrix — Q3 immune and detoxification
Introduced in the third quarter with Thymosin Alpha-1.
05b Condition-specific interest
Glutathione has an enormous global market for an application most people in the peptide space have never considered — intravenous skin lightening — and that market is the subject of explicit regulatory warnings. It also carries an interaction concern that matters more than any of its claimed benefits.
No approval, no trial
Glutathione is not a peptide drug in the therapeutic sense and is not approved for any of the uses below. It is an endogenous tripeptide antioxidant — glutamate, cysteine, glycine — present in every cell. Oral glutathione is poorly absorbed intact, which is the argument for injecting it; the more established route to raising cellular glutathione is supplying cysteine, which is what N-acetylcysteine does at a fraction of the cost.
Actionable warning
Skin lightening — the largest market, and the warnings
Pathophysiology
Glutathione shifts melanin synthesis from darker eumelanin toward lighter phaeomelanin by inhibiting tyrosinase and modulating the melanogenic pathway. The mechanism is real, which is why the market exists.
Mechanistic rationale
No published clinical trial has evaluated injectable glutathione for skin lightening, no dosing guideline exists, and no regulator has approved any injectable product for it. The Philippine FDA has issued a public advisory on unsafe use of glutathione as a skin lightening agent; the US FDA has flagged safety concerns about compounding sterile injectables from glutathione following adverse event reports. Reported harms include anaphylaxis, hepatic and renal dysfunction, neurological effects, and Stevens-Johnson syndrome — a life-threatening skin reaction with a real mortality. Reported adverse events after infusion have included hypotension and dyspnoea requiring hospitalisation.
Community reports
An enormous market across Asia and increasingly elsewhere, generally through cosmetic clinics rather than medical ones. The compound is frequently sold in this library’s market as an antioxidant, by people unaware of what it is mainly used for globally.
Components carrying the argument: Tyrosinase inhibition, melanin pathway shift
Actionable warning
The chemotherapy interaction — the most important item here
Pathophysiology
Several chemotherapy agents and radiotherapy work partly by generating oxidative stress and reactive oxygen species in tumour cells. Glutathione is the cell’s principal endogenous antioxidant, and elevated tumour glutathione is a recognised mechanism of resistance to platinum agents.
Mechanistic rationale
Supplementing a systemic antioxidant during treatment that depends on oxidative damage carries a live concern about reducing the effectiveness of curative therapy. This is not hypothetical caution applied for form — it is one of the few places in this library where an intervention that is otherwise fairly harmless could plausibly make a curable cancer less curable. Anyone in cancer treatment should raise antioxidants with their oncology team before, not after.
Community reports
Widely used during cancer treatment for fatigue and for neuropathy, frequently without the oncologist knowing.
Components carrying the argument: Antioxidant capacity — the mechanism, working against treatment
Study — studied, inconsistent, and complicated by the above
Chemotherapy-induced peripheral neuropathy
Pathophysiology
Platinum agents and taxanes damage peripheral nerves, producing a dose-limiting and frequently permanent neuropathy with no established preventive treatment.
Mechanistic rationale
Glutathione has been studied for platinum-induced neuropathy with inconsistent results across trials. The rationale is sound and the evidence never consolidated. And the same trials sit under the shadow of the interaction concern above — which is precisely why this is an oncology decision rather than a self-directed one.
Community reports
Used in this context. ARA-290 has better neuropathy trial evidence, in different populations, without the antioxidant interaction question.
Components carrying the argument: Antioxidant protection of peripheral nerve
Theorized — with one genuinely established use nearby
Liver disease and detoxification
Pathophysiology
The liver has the highest glutathione concentration of any organ and depends on it for phase II conjugation and for handling reactive metabolites.
Mechanistic rationale
The one indisputable clinical fact in this area is that N-acetylcysteine is the antidote for paracetamol overdose, and it works by replenishing hepatic glutathione — by supplying cysteine, the rate-limiting precursor, orally or intravenously. That is a genuinely life-saving, evidence-based use of glutathione biology, and it does not involve injecting glutathione. In fatty liver and general "detox" contexts the evidence thins out to nothing comparable.
Community reports
"Detox" framing dominates the marketing. The liver does not require assistance to perform conjugation reactions in a person without liver disease.
Components carrying the argument: Hepatic conjugation and reactive metabolite handling
Study — investigated, and did not deliver
Parkinson disease
Pathophysiology
Glutathione depletion in the substantia nigra is one of the earliest identified biochemical changes in Parkinson disease, which made it an obvious therapeutic target.
Mechanistic rationale
Intravenous and intranasal glutathione have been studied in Parkinson disease, and the trials did not establish clinical benefit. It is a clean example of the recurring pattern: a well-documented deficiency in a specific tissue does not mean that supplying the depleted molecule systemically corrects the disease.
Community reports
Still used in this context on the strength of the biochemistry rather than the trial results.
Components carrying the argument: Nigral oxidative stress
Theorized — and antioxidant supplementation has a history
General antioxidant and immune claims
Pathophysiology
Oxidative stress contributes to a wide range of pathology, and glutathione is the principal intracellular antioxidant.
Mechanistic rationale
The generic antioxidant argument has a poor track record in trials: several large antioxidant supplementation studies found no benefit, and some found increased mortality or cancer incidence — beta-carotene in smokers being the best-known example. Reactive oxygen species also have physiological signalling roles, including in exercise adaptation, and blunting them indiscriminately is not obviously desirable.
Community reports
The dominant framing in the peptide market, generally without reference to how antioxidant supplementation has performed when tested.
Components carrying the argument: Systemic antioxidant capacity
| Use | Evidence | The thing to know |
|---|---|---|
| Skin lightening | No trials; regulator warnings | Anaphylaxis, hepatic/renal, Stevens-Johnson reported |
| During chemotherapy | — | May reduce efficacy of oxidative treatment |
| Chemo-induced neuropathy | Inconsistent trials | An oncology decision, not a self-directed one |
| Liver / paracetamol | Established — for NAC | NAC supplies cysteine orally or IV |
| Parkinson disease | Trials did not deliver | Documented deficiency ≠ correctable by supply |
| General antioxidant | Poor trial record | Some antioxidant trials found harm |
| Oral glutathione | Poorly absorbed intact | NAC is the cheaper, evidenced route |
What actually has evidence for these conditions
If raising cellular glutathione is the goal: N-acetylcysteine supplies cysteine, the rate-limiting precursor, is orally active, inexpensive, and is the established route — it is the paracetamol overdose antidote for exactly this reason. Dietary sulphur amino acids and adequate protein matter too.
For skin tone and pigmentation: sun protection first, since ultraviolet exposure drives most unwanted pigmentation. Topical options with evidence include hydroquinone under supervision, azelaic acid, topical retinoids, niacinamide and tranexamic acid, plus chemical peels and laser under dermatological care. None requires a cannula.
During cancer treatment: supportive care is a specialist field with its own evidence base. Antioxidant and immune-modulating supplements are a genuine interaction question and belong in a conversation with the oncology team.
For Parkinson disease: levodopa remains the most effective symptomatic treatment, alongside dopamine agonists, MAO-B inhibitors, and exercise — which has among the best evidence of any non-pharmacological intervention in this disease.
06 Handling, reconstitution & storage
Physical-chemistry reference for laboratory handling of the lyophilised material. Reproduced so that stability and concentration mathematics can be studied — see the calculator for the arithmetic and the reconstitution guide for sterile technique.
Reconstitution
Supplied as a lyophilised powder, commonly 600, 1200 or 2000 mg per vial in the research market. Reconstituted solutions oxidise readily — glutathione converts to its disulphide form (GSSG) on exposure to air, which is the inactive species. Because doses are in hundreds of milligrams, the concentration chosen determines whether a dose fits in a syringe at all: a 1200 mg vial in 3 mL gives 400 mg/mL, so a 200 mg dose is 0.5 mL — 50 units, half a 1 mL syringe.
Storage
Powder: refrigerated or frozen, protected from light and air. Reconstituted: refrigerated and used promptly.
Common vial sizes
Commonly 1200 mg vials; also oral capsules and liposomal preparations.
Stability notes
Oxidation is the governing concern rather than proteolysis. A solution that has been sitting is progressively less reduced glutathione and more GSSG.
07 Legal & regulatory status
Regulatory status changes and differs by country. This is a summary for orientation, not legal advice — check your own jurisdiction.
Not approved as an injectable therapeutic in most jurisdictions. Oral glutathione is sold as a dietary supplement; injectable glutathione is offered by clinics under practice-of-medicine arrangements rather than on the basis of an approved indication.
The FDA and several national regulators have issued specific warnings about unapproved injectable glutathione marketed for skin lightening, citing safety and product-quality concerns. N-acetylcysteine, by contrast, is an established medicine.
Regulatory and trial claims re-checked against primary sources on 16 August 2026. Checked: regulator advisories on IV skin lightening. Approvals, trial readouts and compounding decisions move faster than anything else on this page — a date here means someone looked, not that nothing has changed since.
Anti-doping
Athletes subject to WADA, USADA, UKAD, NCAA or military testing should assume any peptide is prohibited unless they have verified otherwise against the current WADA Prohibited List. Several classes here (growth-hormone secretagogues, TB-4 analogues, metabolic modulators) are explicitly named. Check the current list — it is republished annually.
§ Sources & further reading
Links resolve to PubMed records, trial registries, publisher pages or primary documents. Where a body of work rather than a single paper is cited, the link opens a PubMed query so the full result set — including newer papers than this page — can be reviewed. Verify every claim against the primary source before relying on it.
- PubMed: N-acetylcysteine, glutathione repletion and clinical use (live query)Database or literature search
- PubMed: oral and liposomal glutathione supplementation — bioavailability trials (live query)Database or literature search
- PubMed: glutathione for skin lightening — efficacy, injectable use and safety warnings (live query)Database or literature search
- PubMed: glycine and N-acetylcysteine (GlyNAC) supplementation in older adults (live query)Database or literature search
Reminder
For educational and research reference only. Nothing on this site is medical advice, a recommendation, or an instruction to administer any substance to a human being. Every figure on this page is a record of what has been reported, not a recommendation. Full disclaimer.