A three-amino-acid antioxidant every cell makes, sold as an oral supplement, skin cream and IV drip, mostly for skin lightening.
Also called GSH, Reduced glutathione, L-glutathione, Glutathione reduced, gamma-glutamylcysteinylglycine, Oxidized glutathione (GSSG), Liposomal glutathione, Setria glutathione, Tathion, Glutathione IV drip, Glutathione injection
When Glutathione's status or evidence changes, it's in the next morning's email.
Glutathione is a tripeptide made of glutamate, cysteine and glycine. Your cells build it themselves, and it is the main molecule they use to neutralize reactive oxygen and to help the liver clear drugs and toxins. People take it by mouth as a supplement, put it on the skin in creams, and get it as an IV or intramuscular injection. In Japan an injectable glutathione called Tathion is a prescription drug for uses that include liver disease, eczema and melasma. In the US no glutathione drug is FDA-approved; injections come from compounding pharmacies.
Whether swallowed glutathione reaches the blood was doubted for decades. A 1992 study in 7 volunteers found no rise in blood glutathione after a single 3 g dose. Later trials that dosed daily for weeks did find higher levels: in a 6-month trial in 54 adults, 1,000 mg a day raised glutathione in red blood cells, plasma and immune cells by 30 to 35%. A 4-week trial of 500 mg twice a day in 40 adults found no change.
The skin-lightening evidence comes from small trials, mostly run in Southeast Asia. In a placebo-controlled trial of 60 Thai medical students, 500 mg a day by mouth lowered the skin's melanin reading more than placebo at 2 of 6 body sites. A second trial in 60 Thai women taking 250 mg a day found no significant difference from placebo overall. A 2% lotion lightened the treated side of the face in 30 women, in a trial run by the company that makes the ingredient. IV glutathione for skin lightening has only one placebo-controlled trial, which missed statistical significance, and it carries real risks. FDA warned in 2019 and again in August 2026 about patients who got fevers, chills and sepsis-like reactions from injectable glutathione made with contaminated dietary-supplement-grade powder.
What it binds to, and what happens inside the body after that, step by step.
Glutathione's cysteine carries a free thiol (-SH) group that gives up electrons to neutralize reactive oxygen species, turning two glutathione molecules into one oxidized glutathione (GSSG); enzymes then recycle it. It also binds drugs and toxins in the liver so they can be excreted. For skin color, lab studies show it inhibits tyrosinase, the enzyme that starts melanin production, and shifts pigment cells from dark brown-black eumelanin toward lighter red-yellow pheomelanin. Swallowed glutathione is largely broken down in the gut and liver by gamma-glutamyltransferase, which is why oral absorption has been questioned.
Human results and animal results are kept apart below. A result in rats tells you a mechanism is plausible. It does not tell you what happens in a person.
The A grade rests on glutathione being a prescription drug in Japan and on several small placebo-controlled trials, not on proof of a health benefit: no trial shows that taking extra glutathione improves a health outcome. Daily oral doses raised blood glutathione in a 6-month Penn State trial and a small uncontrolled Penn State pilot, but not in a 4-week trial of 500 mg twice a day. For skin, one oral trial and one company-run topical trial found modest lightening, a second oral trial missed significance on its main measure, and IV glutathione for skin lightening and for Parkinson's disease has not beaten placebo.
54 healthy non-smoking adults, 6 months, 250 mg or 1,000 mg a day versus placebo
At 1,000 mg a day, glutathione rose 30 to 35% in red blood cells, plasma and lymphocytes and 260% in cheek cells by 6 months; levels returned to baseline 1 month after stopping.
Read the study40 healthy adults, 500 mg twice a day or placebo for 4 weeks
No change in oxidative stress markers or in red blood cell glutathione compared with placebo.
Read the study60 healthy medical students in Bangkok, 500 mg a day or placebo for 4 weeks
Melanin index fell at all six sites measured, but the difference from placebo was significant at only two: the right side of the face and the sun-exposed forearm.
Read the study60 healthy women in Bangkok, three arms: 250 mg reduced glutathione, 250 mg oxidized glutathione or placebo daily for 12 weeks
Melanin index and UV spots trended lower than placebo with both forms, but the difference was not statistically significant; reduced glutathione cut wrinkles at some sites. The capsules were supplied by the ingredient maker, Kyowa Hakko Bio.
Read the study30 women aged 30 to 50, 2% oxidized glutathione lotion on one side of the face and placebo on the other, twice daily for 10 weeks
The treated side had a significantly lower melanin index than the placebo side at 10 weeks (P<0.001); the authors work for the ingredient maker, Kyowa Hakko Bio, so this is supplier data.
Read the study45 people with Parkinson's disease, nasal glutathione 100 mg or 200 mg three times a day or saline for 3 months
All groups improved, including placebo, and neither glutathione dose beat placebo; one person on the high dose developed cardiomyopathy.
Read the study21 people with Parkinson's disease, IV glutathione 1,400 mg or placebo three times a week for 4 weeks
No significant difference in Parkinson's rating scores; glutathione was well tolerated.
Read the studyNo preclinical studies are listed as key studies here. The human data above carries the evidence.
When a new Glutathione study in people is published, the daily email covers it.
These are questions the published research has not answered.
No FDA-approved glutathione drug exists. Oral glutathione is sold in the US as a dietary supplement and topical glutathione as a cosmetic ingredient. In Japan, Tathion injection (100 to 200 mg once a day, intramuscular or IV) is a prescription drug; the current PMDA label lists sales starting in July 2000 and lists anaphylaxis (under 0.1%) as its serious adverse reaction. The Philippine FDA has publicly warned against IV glutathione for off-label skin lightening, and FDA reviewers told the 2022 advisory committee that Thai authorities banned IV glutathione for skin lightening. In August 2026 FDA reported at least 30 patients with adverse events after IV glutathione made from Medisca dietary-supplement-grade glutathione (lot 229536), and two Texas pharmacies recalled glutathione injectables for high endotoxin. WADA does not name glutathione, but IV infusions or injections of more than 100 mL in 12 hours are a prohibited method (M2.2), which covers many glutathione drips.
When the FDA or WADA changes Glutathione's status, it's in the next morning's email.
How much of Glutathione is left after a single dose
Simple first-order model from the published half-life. Real clearance varies with dose, route, kidney and liver function and formulation. This is not a dosing schedule.
This table records the doses that trials and approved labels used, with the source for each row. It is a record of research, not a recommendation, and it is open to free members.
Which symptoms are expected and which mean stop and get help: side effects and red flags.
Tap a claim to see what the studies found.
A single large dose did not raise blood levels, but daily dosing for 1 to 6 months raised body stores in two trials. A third trial at 500 mg twice a day found no change, so results depend on dose, form and duration.
The only placebo-controlled IV trial lightened 6 of 16 people versus 3 of 16 on placebo, which was not statistically significant. A 2025 systematic review advises against IV use for skin lightening.
Your cells do rely on glutathione to neutralize reactive oxygen and process toxins. That does not mean extra glutathione from a supplement or drip improves detoxification in a healthy person; no trial shows that.
The molecule being natural does not make the product safe. FDA has linked compounded glutathione injections to endotoxin reactions in 2019 and 2026, and allergic reactions and liver injury have been reported.
IV and nasal glutathione trials in Parkinson's disease did not beat placebo.
These pairings come up often. Almost none have been tested together in a trial, and the evidence note on each says so plainly.
Clinics add vitamin C to glutathione drips on the idea that it keeps glutathione in its reduced form and adds its own lightening effect.
EvidenceNo trial has isolated the combination's benefit, and the added vitamin C makes it impossible to tell which ingredient caused any effect.
Wellness clinics sell them together as an antioxidant and energy infusion.
EvidenceNo published trial has tested this pair. Both are often given by IV, and drips over 100 mL in 12 hours are banned for athletes.
The Japanese injection is supplied as freeze-dried powder with its own solvent and is stored per the label. Oral supplements are kept dry at room temperature per the package.
Reduced glutathione oxidizes in solution over time, so the Japanese label has it dissolved just before use. Compounded vials should follow the pharmacy's beyond-use date.
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