Glutathione
GSH · the cell's principal intracellular antioxidant (a tripeptide)
Glutathione (GSH) is the body's principal intracellular antioxidant — a small tripeptide of glutamate, cysteine and glycine that nearly every cell makes for itself and holds at millimolar concentrations. Its chemistry is real and important: a reactive thiol (–SH) on the cysteine neutralizes reactive oxygen species, regenerates other antioxidants, and conjugates toxins for clearance. That biological importance is exactly what the supplement and IV-clinic industry sells against — yet its two biggest commercial claims are its weakest. Whether swallowing or injecting glutathione meaningfully raises your antioxidant status is genuinely contested (oral bioavailability is poor; an IV dose clears in minutes), and its dominant real-world use — intravenous skin-lightening — is off-label, lacks robust efficacy data, and has drawn an explicit national-regulator safety advisory.
The short version
Glutathione is a tiny molecule your cells make on their own — three amino acids strung together — and it is one of the most important antioxidants inside the body. It mops up cellular 'rust' (reactive oxygen), helps recycle vitamins C and E, and tags toxins so the liver can clear them.
Because it sounds powerful, it is sold heavily as a pill, an IV drip, and especially as a skin-whitening injection. Here is the honest catch: the science behind the sales pitch is shaky. Swallowed glutathione is largely broken down in the gut, an IV dose disappears from the blood within minutes, and the skin-lightening use is unapproved, unproven, and has been flagged by drug regulators for serious side effects.
One common mix-up worth fixing: the emergency antidote for acetaminophen (Tylenol) overdose is N-acetylcysteine, a glutathione building block — not glutathione itself.
Molecular identity
Specs
- Molecular weight
- 307.33 g/mol
- Molecular formula
- C10H17N3O6S
- Monoisotopic mass
- 307.0838 Da
- Water solubility
- 292.5 mg/mL (water)
- XLogP
- −4.5 (highly hydrophilic)
- Topological polar surface area
- 160 Ų
- H-bond donors / acceptors
- 6 donors · 8 acceptors
- CAS / UNII
- 70-18-8 · GAN16C9B8O
- Oxidized form (GSSG)
- C20H32N6O12S2 · 612.6 g/mol
- Structure
- γ-L-glutamyl-L-cysteinyl-glycine (tripeptide; non-ribosomal, γ-peptide bond)PubChem CID 124886
- IUPAC name
- (2S)-2-amino-5-[[(2R)-1-(carboxymethylamino)-1-oxo-3-sulfanylpropan-2-yl]amino]-5-oxopentanoic acidPubChem CID 124886
- Molecular role
- Principal intracellular antioxidant; glutathione-peroxidase cofactor + glutathione-S-transferase substrate (redox / Phase II detox)Research literature
- Plasma half-life
- ~14 min (human IV; t½ 14.1 ± 9.2 min, n=10)PMID 1907548Half-life curve →
- Regulatory status
- Endogenous antioxidant + dietary supplement; injectable/IV glutathione is compounded, not FDA-approved as a drugResearch literature
Plain English
Mechanism
Glutathione is the cell's master thiol antioxidant. The free sulfhydryl (–SH) group on its cysteine residue is the reactive part: it donates electrons to neutralize reactive oxygen and nitrogen species, in the process being oxidized to its dimer GSSG (two glutathiones joined by a disulfide bond). The enzyme glutathione reductase then regenerates GSH using NADPH, and the ratio of reduced (GSH) to oxidized (GSSG) glutathione is one of the cell's central readouts of redox balance.
Beyond direct scavenging, glutathione is the cofactor (a helper molecule an enzyme needs to work) for the glutathione peroxidases (which detoxify hydrogen peroxide and lipid peroxides — two damaging by-products of oxidation) and the substrate for the glutathione-S-transferases, which conjugate (chemically attach) glutathione onto xenobiotics (foreign chemicals), drugs and electrophiles in Phase II detoxification (the liver's tagging step that prepares toxins for removal) — making them water-soluble for excretion via the mercapturic-acid pathway. Review literature also describes glutathione regenerating the oxidized (electron-depleted) forms of vitamins C and E.
Structurally, glutathione is unusual: it is built by two enzymes (glutamate-cysteine ligase, the rate-limiting step — the slowest reaction that caps how fast the whole pathway runs — then glutathione synthetase) rather than on the ribosome (the cell's normal protein-assembly machine), and the bond between glutamate and cysteine is a γ-peptide bond — formed from glutamate's side-chain carboxyl, not the usual α-carboxyl (the linkage that joins amino acids in ordinary proteins). That non-standard linkage is what makes it resistant to ordinary peptidases (the enzymes that chop peptides apart).
Why people reach for it
Potential benefits
Glutathione is reached for as the body's master antioxidant — and the honest appeal is its real, textbook biochemistry, not the oversold IV-clinic claims. Here's what draws people to it.
- The body's master antioxidant — Its core identity. The reactive thiol on Glutathione's cysteine neutralizes reactive oxygen species directly — the cell holds it at high concentrations precisely because it's the front-line defense against oxidative 'rust.'
- Detox and liver support — Glutathione is the substrate the liver's Phase II detox enzymes use to tag toxins and drugs for clearance, and the liver holds the most of it — which is why it's reached for on detoxification and liver-context goals.
- Recharges your other antioxidants — Beyond acting alone, Glutathione regenerates the spent forms of vitamins C and E, so it functions as the hub that keeps the wider antioxidant network running.
- An injection route that sidesteps the gut — Swallowed Glutathione is largely broken down in the gut; injecting it bypasses that degradation — the honest practical reason people choose the SC/IM route over oral capsules.
- A redox base that pairs with NAD+ — Because it runs on the NADPH that NAD+ metabolism supplies, it complements NAD+ cleanly — Glutathione does the radical scavenging while NAD+ keeps the recycling machinery charged.
Sources:PMID 6137189PMID 15822171PMID 24791752
What people reach for Glutathione for, drawn from its well-established antioxidant and detox biochemistry and how it's used — not proven outcomes. Honest limits: whether swallowing or injecting it meaningfully raises antioxidant status is contested, and the IV skin-whitening use is off-label, unproven, and carries a regulator safety advisory. No medical claims.
Implied timing
Best time to dose
Implied best time
Morning (or consistent)
Most people take Glutathione in the morning or after a workout; there's no strong time-of-day requirement, so consistency matters more than the exact hour.
- Glutathione's job is ongoing antioxidant and detox support rather than a single timed pulse, so there's no circadian constraint forcing a particular hour — a regular, consistent schedule is what matters.
- Morning fits its daytime antioxidant role; a post-workout dose is the other common choice, on the reasoning that it lines up with the transient rise in oxidative stress that exercise produces.
- It clears the blood fast (human IV plasma half-life ~14 min), so the value is in regular exposure feeding the body's redox pool, not in catching a specific peak — which again points to consistency over timing.
No study establishes an ideal time of day for Glutathione — this is reasoned from its antioxidant/detox mechanism and how it's used. As a rule of thumb most peptide dosing lands in the midday-to-evening window; for Glutathione, morning (or simply a consistent time) is the practical lean.
Sources:PMID 1907548
How to run it
Dosing & protocol
Glutathione is dosed here as a subcutaneous (SC) or intramuscular (IM) injection — the form the Ki product page and on-page calculator are built for. Injection bypasses the gut's degradation of the tripeptide, which is the honest practical argument for the injectable route over oral. Community SC/IM protocols run 200–600 mg per session; clinical IV protocols used in infusion settings are higher and administered by a practitioner. The numbers below follow the injectable-convention ranges from the file's calculator defaults (600 mg vial / 6 mL bacteriostatic water).
Community and practitioner convention, not a randomized-trial-proven injectable dose — the human studies on glutathione used oral or IV routes; SC/IM convention is extrapolated from mechanism and clinic practice. This page carries the injectable-first standard and presents oral-bioavailability context in the FAQ.
Tiered dose ranges
Most SC/IM protocols scale dose to goal intensity.
- Low / maintenance:
- 200 mg per session, 2–3× per week — antioxidant maintenance, general redox support, or first testing tolerance.
- Standard:
- 400 mg per session, 2–3× per week — the mid-range most practitioners use for ongoing antioxidant or liver-support goals.
- Higher / acute:
- 600 mg per session, up to daily — the upper SC/IM convention range; clinical IV settings go higher (1–2 g or more), but those require practitioner administration.
Subcutaneous administration
Inject into subcutaneous fat; site, rotation, and timing are the actionable choices.
- Injection site:
- Abdomen (a few inches from the navel), outer thigh, or love-handle area. Rotate sites between sessions to prevent local irritation.
- Measuring the dose:
- Standard mix: 600 mg vial + 6 mL bacteriostatic water = 100 mg per mL. On a U-100 insulin syringe (100 IU = 1 mL): 200 mg = 2 mL (draw 2 syringes or a 2 mL syringe) · 400 mg = 4 mL · 600 mg = 6 mL full vial. The calculator adjusts these for any vial size.
- Time of day:
- No strong circadian constraint for glutathione. Morning or post-workout are the most common choices — post-workout may align with the transient increase in oxidative stress that antioxidant support is meant to address.
- Food window:
- Subcutaneous injection is independent of meals — no absorption competition with food.
Cycle & washout
Glutathione is endogenous and generally tolerated continuously, but pulsed protocols are also used.
- Continuous approach:
- Some practitioners run low-to-standard doses (200–400 mg) 2–3× per week indefinitely for ongoing redox or liver support — consistent with its endogenous role.
- Pulsed cycle:
- 4–8 weeks of regular injection, then a 2–4-week break. Used when following a structured detox or antioxidant-loading protocol.
- Washout check:
- Erythrocyte (red blood cell) GSH level or the GSH:GSSG ratio (reduced-to-oxidized glutathione — the cell's redox readout) can be tracked during a washout to gauge whether baseline redox status has shifted.
Reconstitution at a glance
The on-page calculator does this live; quick reference for the standard 600 mg vial:
- Mixing:
- 600 mg vial + 6 mL bacteriostatic water = 100 mg per mL. Each mL = 100 IU on a U-100 syringe. Doses: 200 mg = 2 mL · 400 mg = 4 mL · 600 mg = 6 mL.
- Why 6 mL:
- Keeps the concentration at 100 mg/mL — a round number that makes the mg-to-mL math trivial and reduces measuring errors at the syringe.
Substrate the signal needs
Nutritional cofactor precision
Glutathione's cofactor case is textbook biochemistry — the body's own recipe for making and recharging it is well understood. Three functional groups: supply the synthesis substrate, power the recycling enzymes, and amplify the liver context where GSH matters most.
Reasoned from GSH synthesis and recycling biochemistry plus common supplement convention — not a glutathione cofactor study. Doses are practical convention ranges. Feeding the pathway is mechanistic reasoning, not proof the supplement raises your levels.
Supply the synthesis substrate
The body assembles glutathione from three amino acids: cysteine (rate-limiting — the ingredient in shortest supply), glutamate, and glycine. Give it the building blocks.
- NAC (N-acetylcysteine):
- 600–1,800 mg/day in divided doses — the stable cysteine donor that studies lean on to raise glutathione status more reliably than the tripeptide itself. Take with food to reduce GI upset. This is the same precursor logic as the acetaminophen-antidote fact: supply the cysteine, not the finished tripeptide.
- Glycine:
- 1–3 g/day, ideally in the same window as NAC — glycine is the second building block and is often the co-limiting substrate in older adults. Found in collagen/gelatin; a glycine supplement or collagen peptide powder covers both.
- Glutamate / protein adequacy:
- Glutamate (the third precursor) is abundantly available from dietary protein — ensure adequate total protein intake (1.2–2 g/kg bodyweight/day) rather than supplementing glutamate separately.
Power the recycling and peroxidase enzymes
After GSH neutralizes a radical it becomes oxidized (GSSG) and must be regenerated. Two enzyme systems do that work — each needs its own cofactor.
- Selenium:
- 100–200 mcg/day as selenomethionine — selenium is the cofactor physically embedded in the glutathione peroxidase enzymes (selenoproteins). Without adequate selenium, the antioxidant work GSH does is throttled regardless of how much GSH is present. Do not exceed 400 mcg/day (the tolerable upper limit).
- Riboflavin / Vitamin B2:
- 50–100 mg/day — riboflavin (as FAD, flavin adenine dinucleotide) is the cofactor for glutathione reductase, the enzyme that regenerates GSH from GSSG using NADPH. Deficiency slows the regeneration loop.
- Alpha-lipoic acid (ALA):
- 300–600 mg/day with a meal — sits in the same redox network, directly regenerates oxidized glutathione, and recycles vitamins C and E. Also amplifies NADPH availability through mitochondrial enzyme support.
- Vitamin C:
- 500–1,000 mg/day — reduces oxidized glutathione (GSSG) back toward the active GSH form via the ascorbate–glutathione redox cycle. Take separately from ALA if either causes GI sensitivity.
Amplify liver context (milk thistle / silymarin)
The liver is the highest-GSH organ and the primary site of GSH-mediated detoxification — supporting liver glutathione is where the compound's biology is most clinically discussed.
- Silymarin (milk thistle extract):
- 140–420 mg/day of standardized silymarin (70–80% silymarin content) — studies show silymarin upregulates hepatic (liver) glutathione synthesis and supports glutathione-S-transferase activity. Take with a meal containing fat for best absorption. This is an amplification lever, not a substitute for the synthesis precursors.
Combinations + timing
Stacking notes + timing windows
Glutathione's best 'stack partner' is its own synthesis and recycling support — that is not a cop-out; it is the honest biochemistry. The cofactor group above (NAC + selenium + riboflavin + ALA + vitamin C) is the rational stack. A peptide-to-peptide stack exists, but it is honest to say the redox-network support outranks it.
Combinations reasoned from complementary redox mechanisms — not head-to-head trials. Doses are community convention. 'Reached for' describes where users go, not a proven indication.
Glutathione + NAD⁺
The two anchors of the cellular redox economy — GSH handles the oxidative-stress side; NAD⁺ drives the NADPH that recharges it.
- Why it works:
- Glutathione reductase regenerates GSH from GSSG using NADPH (reduced nicotinamide adenine dinucleotide phosphate). NADPH is itself produced from NAD⁺ metabolism via the pentose-phosphate pathway. Running NAD⁺ alongside glutathione keeps the NADPH supply — the fuel for GSH recycling — well stocked, so the two systems reinforce each other rather than competing. Different levers: GSH does the front-line radical scavenging; NAD⁺ keeps the recycling machinery charged.
- The protocol:
- Glutathione 200–400 mg SC/IM 2–3× per week alongside NAD⁺ on its own typical SC schedule (commonly 25–100 mg SC once daily or on a 5-on-2-off rotation). Timing does not need to be synchronized — both are independent injections.
- Outcome:
- The combination reached for in longevity and mitochondrial-health contexts where both oxidative stress and NAD⁺ decline are considered together.
Honest note on peptide stacking
Glutathione's best complement is nutritional, not peptide-to-peptide.
- Why no second peptide here:
- Most peptide pairings on this site work because two peptides target different biological levers (e.g. inflammation + repair). Glutathione's primary job — neutralizing reactive oxygen species and feeding the liver's Phase II detox pathway — is not what other research peptides target, so pairing it with BPC-157 or TB-500 would not create synergy; it would just run two unrelated mechanisms in parallel. The high-synergy partners are NAC (synthesis), selenium (peroxidase), and the recycling cofactors above — those are the same lever, at the step upstream and downstream of the GSH molecule itself.
Reconstitution math
Reconstitution calculator
Reconstitution calculator
Calculated for a 1 mL U-100 insulin syringe (100 units/mL).
Units per dose
600
Draw to this mark on a U-100 syringe
- Volume per dose
- 6 mL
- Doses per vial
- 1
- Concentration
- 100 mg/mL
One vial lasts
- Daily
- 1 days
- Every other day
- 2 days
- 5×/week
- 1 days
- Dose volume (6 mL) exceeds the 1 mL syringe capacity. Use a larger syringe or split the draw.
- Large draw (600 units). Double-check the vial size and dose — a mcg/mg mix-up produces values like this.
Research use only. Not for human consumption. Outputs are reference values based on research literature — verify all measurements independently.
From the studies
Side effects from research
Oral glutathione is generally well tolerated in trials. The serious safety signal is specific to the off-label (outside any approved use) intravenous (IV — into a vein) skin-whitening use: the Philippine FDA (the national drug regulator) issued a public advisory against IV glutathione for skin-lightening, citing toxic effects on the liver, kidneys and nervous system and the risk of severe skin reactions such as Stevens-Johnson syndrome (a rare, life-threatening blistering reaction), alongside infection from unregulated administration; health authorities have also linked the practice to reported deaths. Inhaled glutathione can provoke bronchospasm (a sudden tightening of the airways that makes breathing hard) in susceptible airways.
The overarching safety point: glutathione's risks track the route and the claim. Endogenous (made by the body) and oral glutathione are low-concern; the high-dose, unregulated IV cosmetic use is where documented serious harm appears.
Sources:PH FDA 2019-182
As reported in literature
Research dosing ranges
These are the doses actually used in the published human studies — the evidence the practical figures above lean on, shown separately so research data is never mistaken for a recommended dose. The throughline is that the route (how it enters the body) matters enormously: oral (swallowed) and intravenous (IV — into a vein) glutathione behave very differently, and the headline commercial uses (IV antioxidant 'boosting' and IV skin-whitening) rest on the thinnest evidence.
| Dose | Route | Model | Outcome | Sources: |
|---|---|---|---|---|
| 250 / 1000 mg/day | Oral | Human RCT · 6 months | Raised body GSH stores vs placebo | PMID 24791752 |
| Single oral dose | Oral | Human PK | No acute rise in blood GSH | PMID 1362956 |
| 500 mg/day | Oral | Human RCT · 4 weeks (skin) | Lower melanin index at 2 of 6 sites | PMID 20524875 |
| Off-label | IV | Skin-whitening (clinic use) | No robust efficacy; serious harms reported | PH FDA 2019-182 |
| Per protocol | Intranasal | Parkinson's RCT | No benefit vs placebo | PMID 28436395 |
| Per protocol | Inhaled | Cystic fibrosis RCT | No consistent clinical benefit | PMID 23631796 |
Labs before / during / after
Cofactor blood markers to track
Markers a researcher might track around redox (the body's oxidation-vs-repair balance) / antioxidant status — general context, not glutathione-specific clinical endpoints:
Whole-blood or erythrocyte (red-blood-cell) glutathione and the GSH:GSSG ratio (reduced-to-oxidized glutathione, a direct measure of how much is still 'charged up') as a direct redox readout; and, since glutathione synthesis depends on it, cysteine availability — often the limiting substrate (the ingredient in shortest supply, which caps how much can be made), which is why the precursor (the upstream building block) N-acetylcysteine is studied for raising glutathione.
Sources:PMID 6137189
Quick answers
Frequently asked
Does taking glutathione actually raise my antioxidant levels?
It is genuinely contested. A single oral dose does not meaningfully raise blood glutathione, since much of it is broken down in the gut; a 6-month randomized trial reported that daily oral dosing modestly raised body stores over time. A reliable acute 'boost' from swallowing it is not established, and an IV dose clears from the blood within minutes.
Is IV glutathione for skin-whitening safe or approved?
No. It is off-label and not approved for that use. The Philippine FDA issued an advisory against intravenous glutathione for skin-lightening, citing toxic effects on the liver, kidneys and nervous system and the risk of severe skin reactions, with infection risk from unregulated administration; health authorities have also linked it to reported deaths. Robust efficacy data is lacking.
Is glutathione the antidote for a Tylenol (acetaminophen) overdose?
No — and this is a common mix-up. The antidote is N-acetylcysteine, a glutathione precursor that replenishes the liver's glutathione. Glutathione itself is not the administered antidote.
Is glutathione a peptide?
Technically it is a tripeptide — three amino acids — but an unusual one: it is built by two enzymes rather than on the ribosome, and joined by a γ-peptide bond that resists ordinary peptidases. It is the body's principal intracellular antioxidant, not a signaling peptide.
My glutathione turned cloudy when I mixed it — is that normal?
Usually yes, at first. A 600 mg vial is a dense load of powder, so adding bacteriostatic water can briefly look milky or cloudy — like a shaken snow globe — as the powder disperses. Glutathione is freely water-soluble (it dissolves to about 290 mg/mL, far above the ~100 mg/mL of a standard 600 mg in 6 mL mix), so with a minute or two of gentle swirling it should turn completely clear; add the water down the side of the vial and swirl rather than shake. Discard the vial if the cloudiness will not clear, if particles or a precipitate appear, or if it turns yellow or changes color — glutathione is an antioxidant, so it reacts with air (oxidizes), and a reconstituted vial should be kept refrigerated, out of light, and used within about 28 days. One caution: glutathione can lose strength to oxidation while still looking clear, so 'it looks fine' is not a guarantee — cold storage matters on its own. (This is a different situation from cloudiness when you combine two peptides in one syringe, which usually means they clashed; see the reconstitution and mixing guides.)
Primary sources
References
- PubChem CID 124886PubChem CID 124886
- PubChem CID 65359PubChem CID 65359 (GSSG)
- PMID 6137189Glutathione metabolism (review)
- PMID 15822171Glutathione-S-transferases (review)
- PMID 1362956Witschi et al. 1992 (oral PK)
- PMID 1907548Aebi et al. 1991 (high-dose IV PK in man; plasma t½ 14.1 min, n=10)
- PMID 24791752Richie et al. 2015 (6-mo RCT)
- PMID 20524875Arjinpathana & Asawanonda 2012 (skin RCT)
- PH FDA 2019-182Philippine FDA Advisory No. 2019-182
- PMID 28436395Mischley et al. 2017 (intranasal PD RCT)
- PMID 19230029Hauser et al. 2009 (IV PD pilot)
- PMID 23631796Griese et al. 2013 (inhaled CF RCT)
Reviewed by Ki Researcher Team · Research use only · Not medical advice · Updated 2026-06-04