Glutathione is the body's main antioxidant inside cells, and it is sold both as capsules and as an injection. The question is whether taking it raises levels and helps. The oral trials show that blood levels can rise. None shows a health benefit, and most were small and short. Injected glutathione has been tried in a few small studies, mainly in Parkinson's disease and for skin lightening.
The largest oral trial
Richie and colleagues gave 54 non-smoking adults 250 or 1,000 mg of glutathione a day for six months, with placebo as the comparison. Blood glutathione rose at both doses. Those are blood measurements. The trial did not measure disease, symptoms or any health outcome.
An oral trial with no change
Allen and Bradley randomized 40 healthy adults to 500 mg of glutathione twice a day or placebo for four weeks. Urinary markers of oxidative stress and red-cell glutathione did not differ between the groups. It is a short trial, and its markers did not move.
A liposomal pilot, supported by its maker
Sinha and colleagues gave 12 adults a liposomal glutathione product at 500 mg and at 1,000 mg a day for one month. Glutathione rose in blood, red cells, plasma and white cells. Natural-killer (NK) cell activity rose most by two weeks, by up to 400%. The authors say the sample was too small to compare doses. The research was supported by Researched Nutritionals, which makes the liposomal product.
Injected glutathione
Hauser and colleagues randomized people with Parkinson's disease to intravenous glutathione or placebo in a double-blind pilot and found no significant difference in motor or daily-living scores. Sechi and colleagues gave intravenous glutathione to people with early, untreated Parkinson's disease in an open-label study and reported improvement that faded after treatment stopped. Neither is a trial of health in healthy adults. Injected glutathione for skin lightening has been reviewed in 2026, and the review judged the clinical evidence too limited to support it.
Safety, briefly
The most common side effect in the oral studies reviewed in 2026 was mild stomach upset. The trials were too short and too small to rule out rare harm.
What this does not say
- No trial has shown that glutathione, by mouth or by injection, improves a health outcome.
- The oral trials were small and short (12 to 54 people, up to six months).
- Blood and cell levels are markers. They do not show that a disease is prevented or treated.
- GlyNAC, a combination of glycine and N-acetylcysteine, is a different intervention and is not evidence for glutathione itself.
- We found no controlled trial of injected glutathione that measured a health outcome in healthy people.
How we use this
The glutathione products on this site are capsules and an injection. The oral trials show that blood glutathione can be raised with daily doses; they do not show that it helps. Our physicians say so, and they do not present a rise in blood levels as a result.
For injection there is no controlled evidence of benefit, and we treat it as unproven. We use these studies to show what was measured and how little is known.
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- 1.Richie JP et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Eur J Nutr 2015 (online 2014). European Journal of Nutrition
- 2.Allen J, Bradley RD. Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers. J Altern Complement Med 2011. Journal of Alternative and Complementary Medicine
- 3.Sinha R et al. Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function. Eur J Clin Nutr 2018. European Journal of Clinical Nutrition
- 4.Hauser RA et al. Randomized, double-blind, pilot evaluation of intravenous glutathione in Parkinson's disease. Mov Disord 2009. Movement Disorders
- 5.Sechi G et al. Reduced intravenous glutathione in the treatment of early Parkinson's disease. 1996. Progress in Neuro-Psychopharmacology and Biological Psychiatry
- 6.Aloraini K et al. Glutathione for skin lightening via intravenous, oral, and topical routes: a critical narrative review of current evidence, safety, and the evidence-practice gap. J Med Life 2026. Journal of Medicine and Life