Overview
Glutathione is the body's most abundant intracellular antioxidant — a tripeptide of glutamate, cysteine, and glycine — central to phase II hepatic detoxification, redox cycling, and conjugation of reactive electrophiles. Its inclusion in this 'peptide companion' library follows the same logic as NAD+: it is technically a peptide (a tripeptide), is heavily marketed alongside peptide regimens, and most users encounter it through IV-clinic protocols rather than as a primary intervention. The strongest clinical evidence is for paracetamol (acetaminophen) overdose, where N-acetylcysteine — a glutathione precursor — is a Tier 1 antidote. The IV-clinic marketing for skin lightening, brain-fog 'detox,' and general anti-aging runs well past the supporting evidence, particularly given persistent questions about IV / oral glutathione bioavailability and its rapid plasma clearance.
Mechanism
Acts as the primary intracellular thiol antioxidant, donating its cysteine sulfhydryl to neutralize reactive oxygen species and to conjugate electrophiles (xenobiotics, toxic metabolites) for biliary or renal excretion via glutathione S-transferases. Cellular GSH:GSSG ratio is a key redox signal. Oral glutathione is largely degraded in the GI tract, with cysteine being the limiting precursor for de novo synthesis — a major reason that NAC (N-acetylcysteine), a stable cysteine precursor, is the clinical workhorse rather than oral GSH. IV glutathione bypasses GI degradation but plasma half-life is short (~minutes) and tissue uptake mechanisms are not fully characterized.
Evidence by indication
We classify each indication separately. The same peptide can be Tier 1 for one use and Tier 4 for another. Tiers reflect the published literature, not the strength of community framing.
Paracetamol (acetaminophen) overdose (via NAC precursor mechanism)
N-acetylcysteine, the rate-limiting cysteine precursor for hepatic glutathione synthesis, is the standard-of-care antidote for paracetamol overdose. Prescribed by ED protocol; survival benefit demonstrated in multiple decades of clinical use. Indication is for NAC, not glutathione directly — but the mechanism is glutathione restoration in hepatocytes.
Skin lightening (cosmetic)
Heavily marketed in Asian cosmetic markets (Philippines, Thailand, Indonesia). Some small RCTs (Sonthalia 2018 review) report modest skin-tone changes with oral glutathione; effect sizes are small and clinical relevance modest. Tier 3 for a cosmetic indication.
Liver disease / NAFLD / general 'detoxification'
Mechanistic plausibility from the role of glutathione in phase II hepatic detoxification. Small RCTs in NAFLD report modest improvements in liver enzymes; clinical-outcome data is limited. The 'detox' marketing language is non-clinical.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
Parkinson's disease
Pilot studies (Sechi 1996, Mischley 2017) of IV or intranasal glutathione in PD report some symptomatic improvements. Larger trials are limited. Tier 3 reflects underpowered studies with consistent but small signals.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
General anti-aging / longevity / 'master antioxidant' marketing
IV-clinic marketing positions glutathione as a general anti-aging intervention. There is no RCT supporting this in healthy adults. Mechanism-as-evidence reasoning amplified by clinic-economics incentive.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
Studied dose ranges
The ranges below come from published trial protocols where available, and from documented self-experimenter consensus where the literature does not include human dose-finding work. The notes flag which is which.
Clinic IV glutathione doses range widely from 200 mg to 2000+ mg per infusion. Note the unit math: 1000 mg = 1,000,000 mcg. The Asian skin-lightening market often uses higher doses (1500–2000 mg) 1–2× per week.
Compounded SubQ glutathione is increasingly common as a 'home protocol' alternative to clinic IV. No published RCT validates SubQ bioavailability or efficacy.
Liposomal-encapsulated oral glutathione is sold to bypass GI degradation. Some bioavailability studies (Sinha 2018, Richie 2015) report measurable increases in body GSH stores; others are null.
Contraindications
- Asthma (rare reports of bronchospasm with IV glutathione, particularly in sulfite-sensitive patients)
- Active sulfite hypersensitivity
- Pregnancy and breastfeeding (limited human safety data outside the NAC paracetamol-overdose context)
- Cysteine metabolism disorders
- Known hypersensitivity to glutathione or formulation excipients
Reported side effects
- IV: rare bronchospasm, flushing, nausea during rapid infusion
- SubQ: injection-site stinging (sulfur compounds are irritating)
- Oral: GI upset, sulfur-burp odor (the cysteine smell)
- Inhaled / nebulized: bronchospasm has been reported and is a real concern in asthma
- Headache
- Skin rash (rare allergic reaction)
Reconstitution & storage
Compounded sterile glutathione is supplied either as a prefilled vial of solution (200 mg/mL is common) or as lyophilized powder reconstituted with sterile preservative-free saline. Many compounding pharmacies use preservative-free saline rather than BAC water because the benzyl alcohol can be irritating with the volumes typical of glutathione dosing. Dose volumes for IV / SubQ doses are often multi-mL.
Storage. Compounded sterile solutions: refrigerate 2–8 °C, follow vendor expiration (typically 14–30 days once compounded). Lyophilized powder: refrigerate; reconstituted within 14 days. Liposomal oral: room temperature, dry, protected from light per label.
Open the peptide calculator → to compute exact draw volumes for your specific vial and BAC water choice.
Editorial note
DRAFT — pending Wayne's review. Glutathione is technically a tripeptide, so it fits the 'companion peptide' library more cleanly than NAD+. Two-tier editorial framing: name the Tier 1 evidence (NAC for paracetamol) honestly, and refuse to soften the Tier 4 'master antioxidant' clinic-marketing claims. The skin-lightening market is large enough that the Tier 3 cosmetic indication is real and shouldn't be dismissed, but should be framed as cosmetic, not health.
Citations
- [1]Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. Analysis of the national multicenter study (1976 to 1985)Smilkstein MJ, Knapp GL, Kulig KW, Rumack BH · New England Journal of Medicine · 1988 · PMID 3047581Foundational clinical evidence for NAC in paracetamol overdose — the indirect Tier 1 indication for glutathione restoration.View source
- [2]Glutathione as a skin whitening agent: facts, myths, evidence and controversiesSonthalia S, Jha AK, Lallas A, Jain G, Jakhar D · Indian Dermatology Online Journal · 2018 · PMID 29688177Cross-trial review of glutathione skin-lightening evidence — anchors Tier 3 for the cosmetic indication.View source