Glutathione: The Master Antioxidant and Its Absorption Limits
The body's master antioxidant tripeptide — sold as an IV/injectable and oral wellness supplement for detox, skin, and liver support.
What is Glutathione?
Glutathione is a tripeptide (glutamate-cysteine-glycine) produced naturally in the liver and considered the body's primary intracellular antioxidant, neutralizing free radicals and supporting detoxification pathways. Though technically a tripeptide, it's marketed and used almost exclusively as a wellness supplement rather than a research peptide — sold as an oral/liposomal capsule and as an IV or intramuscular injectable at wellness clinics, often alongside NAD+ on the same infusion menu. It's regulated as a dietary/food ingredient rather than an approved drug, and injectable glutathione marketed specifically for skin lightening has drawn FDA scrutiny.
Quick facts
- Molecular Formula
- C10H17N3O6S
- Molecular Weight
- 307.32 g/mol
- CAS Number
- 70-18-8
- Class
- Tripeptide antioxidant (Glu-Cys-Gly), produced endogenously
- Brand Names
- No trademarked brand — sold as a generic antioxidant supplement
- Legal Status
- OTC dietary supplement (oral); injectable skin-lightening use is not FDA-approved and has drawn FDA import warnings
- Category
- Antioxidant & Detox Support
- Storage
- Store the lyophilized vial refrigerated (2-8°C) or at -20°C, away from light. Once reconstituted, keep refrigerated at 2-8°C and use promptly.
Dosing at a glance
Injectable glutathione protocols vary by vendor; a common convention is a 600mg vial reconstituted with bacteriostatic water for IM/IV clinic administration. Run the numbers in the reconstitution calculator.
Doses shown are those reported in published research, not a recommendation.
Glutathione Mechanism of Action
Master Antioxidant
Glutathione is a tripeptide of glutamate, cysteine, and glycine, synthesized primarily in the liver. Its central thiol (-SH) group allows it to neutralize reactive oxygen species and regenerate other antioxidants like vitamins C and E, making it a core component of the body's intracellular antioxidant defense and detoxification machinery, including conjugation reactions in liver Phase II metabolism.
Endogenous Recycling
Rather than being consumed and excreted like a typical supplement, glutathione is continuously recycled between its reduced (GSH) and oxidized (GSSG) forms via glutathione reductase, an enzymatic cycle that regenerates the antioxidant pool from within cells rather than relying solely on external replenishment.
Glutathione Dosage and Protocols
Route-Dependent Protocols
Injectable protocols commonly use 200–600mg IM or IV, a few times weekly, at wellness clinics. Oral liposomal supplements are commonly dosed at 250–1000mg daily. There is no FDA-established clinical dosing standard for either route.
Glutathione Side Effects and Safety
Reported Effects
Glutathione is generally well tolerated. Rare reports include mild abdominal cramping or bloating with oral use, and injection-site irritation with IM/IV use. Nebulized or very high-dose IV glutathione has been associated with rare bronchospasm reports in patients with asthma. Sulfa/sulfite-sensitive individuals should discuss injectable formulations with a clinician, as some preparations contain sulfite preservatives.
Glutathione Research Evidence
Oral vs. Injectable Evidence
Oral glutathione has historically faced bioavailability questions, since it's broken down by digestive enzymes before absorption — liposomal and S-acetyl formulations were developed to address this. Injectable/IV glutathione bypasses digestion entirely and is popular in wellness clinics for detox, skin, and liver-support claims, though robust controlled human trial data supporting these specific outcome claims is limited.
Regulatory and Legal Status
Glutathione is available over-the-counter as an oral dietary supplement — the FDA treats it as a GRAS (generally recognized as safe) food/dietary ingredient, not an approved drug. Injectable glutathione marketed specifically for skin lightening is not FDA-approved for that use, and the FDA has issued import alerts regarding unapproved injectable skin-lightening glutathione products sourced from overseas.
Glutathione Stacking and Combinations
Common Wellness Pairings
Glutathione is frequently paired with NAD+ on wellness-clinic IV menus as complementary cellular-health/antioxidant support, rather than combined with peptides in a dosing-protocol sense.
Glutathione Pharmacokinetics
Rapid Intracellular Turnover
Free circulating glutathione has a very short plasma half-life — on the order of minutes — because it's rapidly taken up and recycled intracellularly via the glutathione redox cycle rather than persisting in the bloodstream like a conventional drug.
Contraindications
- pregnancy
- sulfa/sulfite sensitivity
Frequently asked questions
What is a typical Glutathione dose?
Published research protocols report 200–1000 mg, route-dependent. This is the range described in the literature, not a recommendation.
What is the half-life of Glutathione?
Very short in circulation (minutes) — rapidly recycled intracellularly via the glutathione redox cycle rather than persisting as free plasma glutathione.
Is Glutathione backed by strong evidence?
Glutathione carries a REGEN research grade of D. REGEN Research Tier D — no approval for the uses it is sold for, and the FDA has warned specifically about compounded injectable forms.
How is Glutathione administered?
Routes reported in the literature: intravenous, intramuscular, oral.
Who should avoid Glutathione?
Contraindications noted in the literature include pregnancy, sulfa/sulfite sensitivity.