Glutathione

Grade B: Human evidence, not approved for this use

TL;DR: Glutathione is an endogenous tripeptide antioxidant synthesized by virtually all human cells; its supplementation is marketed for oxidative stress, immune support, skin lightening, and aging-related conditions. Oral bioavailability is limited because glutathione is extensively hydrolyzed in the gut, though a six-month RCT (PMID 24791752) found that sustained oral supplementation did raise body glutathione stores. A small number of direct oral glutathione RCTs (approximately two to three peer-reviewed trials) show modest effects on systemic oxidative biomarkers, though effect sizes are generally small and clinical significance is unclear. Much of the apparent RCT evidence in the research literature actually measures glutathione as a secondary biomarker in trials of precursors (GlyNAC, NAC, whey protein) or unrelated interventions, inflating the apparent direct trial count. IV glutathione bypasses the bioavailability barrier but introduces a distinct and documented risk profile. No oral or IV glutathione formulation holds FDA approval for any therapeutic indication.

Key Takeaways

Grade B: Human evidence, not approved for this use
Not FDA approved: Not FDA-approved for any indication in oral or injectable form; FDA has issued formal safety warnings about compounded sterile glutathione preparations.
Compounding: Injectable glutathione compounding is not straightforwardly authorized: FDA has documented specific contamination concerns with dietary-ingredient-grade glutathione used to compound sterile products. Oral glutathione is available as a dietary supplement without prescription. As of June 2026, IV compounded glutathione remains in a regulatory gray zone and is not on the FDA 503A Category 1 bulk drug substances list.

Glutathione chemical structure — Structure via PubChem CID 124886

Mechanism

Glutathione functions as the primary intracellular thiol-based antioxidant, directly neutralizing reactive oxygen species and regenerating other antioxidants (vitamins C and E) via the glutathione redox cycle; it also serves as a cofactor in glutathione S-transferase detoxification reactions.

Evidence

Glutathione is an endogenous tripeptide antioxidant synthesized by virtually all human cells; its supplementation is marketed for oxidative stress, immune support, skin lightening, and aging-related conditions. Oral bioavailability is limited because glutathione is extensively hydrolyzed in the gut, though a six-month RCT (PMID 24791752) found that sustained oral supplementation did raise body glutathione stores. A small number of direct oral glutathione RCTs (approximately two to three peer-reviewed trials) show modest effects on systemic oxidative biomarkers, though effect sizes are generally small and clinical significance is unclear. Much of the apparent RCT evidence in the research literature actually measures glutathione as a secondary biomarker in trials of precursors (GlyNAC, NAC, whey protein) or unrelated interventions, inflating the apparent direct trial count. IV glutathione bypasses the bioavailability barrier but introduces a distinct and documented risk profile. No oral or IV glutathione formulation holds FDA approval for any therapeutic indication.

Safety and risks

Oral glutathione at supplemental doses has a generally mild adverse-effect profile in short-term trials, but long-term safety data from controlled studies are lacking. IV compounded glutathione carries substantially greater documented risk. The FDA has formally identified safety concerns with compounded sterile glutathione preparations: in 2019, adverse events were linked to compounded glutathione injections contaminated with bacterial endotoxin at levels up to five times the appropriate limit, prompting an FDA safety notice specifically warning compounders against using dietary-supplement-grade glutathione to manufacture sterile injectables. A 2025 case report described a patient developing systemic inflammatory response syndrome (SIRS) after high-dose unregulated IV glutathione infusion, with fever exceeding 41 degrees Celsius, acute liver injury, and clotting abnormalities. Compounded IV preparations are not subject to the manufacturing quality controls of FDA-approved drugs, creating ongoing contamination and potency risks. IV use for cosmetic indications (e.g., skin lightening) has been independently assessed as posing unacceptable risk-benefit profiles by multiple international health authorities.

Interactions

May theoretically potentiate the effects of platinum-based chemotherapy agents (cisplatin) if used concurrently at high IV doses; clinical significance is not established. No well-characterized pharmacokinetic drug interactions for oral supplemental doses.

Compounding legality

Injectable glutathione compounding is not straightforwardly authorized: FDA has documented specific contamination concerns with dietary-ingredient-grade glutathione used to compound sterile products. Oral glutathione is available as a dietary supplement without prescription. As of June 2026, IV compounded glutathione remains in a regulatory gray zone and is not on the FDA 503A Category 1 bulk drug substances list.

Sources

Glutathione is Not FDA approved. PeptideGrids presents evidence and regulatory status for informational purposes only. We do not sell, supply, source, or help anyone obtain this compound, and we provide no dosing or administration guidance. This is not medical advice; consult a licensed clinician. Full disclaimer.

Last reviewed June 1, 2026 by PeptideGrids editorial team (independently audited).