Glutathione

Overview

Glutathione is an endogenous tripeptide (gamma-L-glutamyl-L-cysteinyl-glycine) that serves as the principal intracellular antioxidant in mammalian cells. It is not FDA-approved as a drug in the US; parenteral glutathione is used off-label (and in some compounding settings) for oxidative stress, hepatic support, and — controversially — skin lightening. The FDA has warned against injectable glutathione for skin lightening (2019) due to reports of serious adverse events.

Mechanism of Action

Glutathione cycles between reduced (GSH) and oxidized (GSSG) forms, donating electrons to reactive oxygen species via glutathione peroxidase. It serves as a cofactor for glutathione S-transferases (GSTs) in Phase II detoxification, maintains reduced protein thiols, supports T-cell proliferation and NK cell cytotoxicity, and regenerates vitamins C and E. Proposed skin-lightening activity is attributed to inhibition of tyrosinase and a shift from eumelanin toward phaeomelanin synthesis, though clinical evidence is limited and largely from small Asian dermatology trials.

Research Summary

A randomized, double-blind pilot trial (Hauser et al., Movement Disorders, 2009, PMID 19230029) tested IV glutathione 1,400 mg three times weekly for 4 weeks in Parkinson's disease (n=21); it was well tolerated but did NOT show a statistically significant effect on UPDRS scores. A large randomized trial of inhaled glutathione (646 mg every 12 hours for 6 months) in cystic fibrosis (Griese et al., Am J Respir Crit Care Med, 2013, PMID 23631796) did not demonstrate clinically relevant improvements in lung function, exacerbations, or quality of life. Oral glutathione has poor bioavailability due to GI degradation, driving investigation of IV, nebulized, liposomal, and sublingual delivery. The FDA issued a 2019 warning about compounded sterile injectable glutathione made from dietary-grade ingredient, citing adverse-event reports (including Stevens-Johnson syndrome, toxic epidermal necrolysis, and kidney dysfunction) particularly in the context of unregulated IV skin-lightening use.

Dosing Information

Reported Side Effects

• Bloating and abdominal cramps (oral administration)
• Zinc depletion with prolonged high-dose use
• Bronchospasm (inhaled formulations)
• Severe cutaneous adverse reactions — Stevens-Johnson syndrome and toxic epidermal necrolysis — reported with unregulated injectable skin-lightening use (FDA 2019)
• Acute kidney injury, thyroid dysfunction, and hypersensitivity reactions reported with unregulated IV use
• Risk of infection / bloodborne pathogen transmission from non-sterile IV administration

Research References

• Randomized, double-blind, pilot evaluation of intravenous glutathione in Parkinson's disease (Hauser et al., Movement Disorders) (2009)
• Regulation of glutathione synthesis (Lu, Mol Aspects Med) (2009)
• Inhalation treatment with glutathione in patients with cystic fibrosis: a randomized clinical trial (Griese et al., Am J Respir Crit Care Med) (2013)
• FDA highlights concerns with using dietary ingredient glutathione to compound sterile injectables (2019)