Peptides · Tripeptide antioxidant (oral, IV, injectable)

Glutathione: what the studies show

Every line below comes from a study, label or regulator record, checked by two models, with the source linked. Information, not medical advice. For adults 18+.

What it is

Glutathione (GSH) is a three-amino-acid molecule (glutamate, cysteine, glycine) that every cell makes. It helps the body handle oxidative stress. It is sold as oral capsules, sublingual and film forms, creams, inhalers and injectable or IV products.^[1]^[2]^[3]
Many papers about glutathione measure the body's own levels or related enzymes. Those papers do not show that taking glutathione works.^[4]

Bottom line

Oral glutathione can raise blood glutathione levels over months in healthy adults, and small trials suggest it lightens skin pigment a little. Proof of benefit for any disease is thin, IV and injected glutathione has little controlled trial support, and FDA has warned compounders about supplement-grade glutathione used in injectables.^[1]^[3]^[5]^[6]

What the human studies found

Body stores, oral (double-blind RCT, 54 non-smoking adults, 6 months, 250 or 1,000 mg a day): blood glutathione rose at both doses. At 1,000 mg, levels were 30 to 35% higher in red cells, plasma and lymphocytes and 260% higher in cheek cells. Levels returned to baseline within a month after stopping. Natural killer cell activity more than doubled in the high-dose group at 3 months.^[1]
Absorption by formulation: in a 2026 crossover study in healthy adults, a 300 mg orally dissolving film gave higher plasma glutathione at 4 and 6 hours than a tablet. The abstract itself says oral availability is still debated.^[2]
Skin lightening: a 2025 systematic review found five RCTs and one open-label study of oral glutathione 250 to 500 mg a day that showed a lower melanin index than placebo. Topical 0.5% glutathione beat 0.1% and placebo. The one placebo-controlled IV study had 6 of 16 responders versus 3 of 16 (p=0.054). Risk of bias was high in about half of the studies.^[3]
IV glutathione, Parkinson disease (double-blind pilot RCT, 21 people, 1,400 mg three times a week for 4 weeks): no significant difference from placebo on the Parkinson rating scale. It was well tolerated.^[5]
IV glutathione, heart attack (RCT, 50 people, 2,500 mg before angioplasty and at 24, 48 and 72 hours): blood markers of oxidative stress were lower than with placebo. In a sub-analysis of a 100-patient trial, hospital stay was 8.6 versus 10.8 days.^[7]^[8]
Inhaled glutathione, cystic fibrosis (double-blind RCT, 153 people aged 8 and older, 646 mg every 12 hours for 6 months): lung function (FEV1), the main outcome, did not differ from placebo.^[9]

Known risks and side effects

Case report: a woman developed shock, fever above 41 degrees C, liver injury and clotting problems within an hour of an unregulated high-dose IV glutathione skin-lightening infusion. She had also been using tirzepatide with low food intake, so the cause is not certain.^[10]
Case report: a 33-year-old woman developed Stevens-Johnson syndrome or toxic epidermal necrolysis, a severe skin reaction, after an IV infusion of glutathione with vitamins C and D. The report says the Philippines FDA warned about this link. A separate case describes the same skin reaction after glutathione whitening pills.^[11]^[12]
In the controlled trials listed above, no safety concerns were reported at the doses and durations studied. They were small, so rare harms would not show.^[5]^[1]^[9]

Legal status

FDA's Compounding Risk Alerts index (2026) lists two glutathione alerts: 'FDA highlights concerns with using dietary ingredient glutathione to compound sterile injectables' (2019-06-07) and 'FDA reminds compounders not to use dietary supplement grade glutathione for injectables' (2026-08-27). Only the headlines are in the record.^[6]
On FDA's 503A bulk drug substances list (updated 2026-05-14), glutathione is in category 1, substances still under evaluation. It is not on the 503A bulks list.^[13]