Glutathione (oral)
Summary
Oral glutathione can raise blood glutathione: a 6-month trial at 250–1,000 mg/day found dose-dependent rises, but a 4-week trial at 1,000 mg/day found none (grade C, mixed). Small Thai trials at 250–500 mg/day found modest skin lightening (grade C). Long-term safety beyond 6 months is unstudied.
Key facts
- A tripeptide of glutamate, cysteine and glycine made inside cells; supplements are reduced glutathione (GSH), sometimes liposomal[1][2]
- None set; glutathione is not an essential nutrient because the body makes it[1]
- No treatment-related adverse events reported in the cited trials; one skin trial noted both groups tolerated it well[4][5]
- 5 graded human outcomes on this page
- October 10, 2026
How it works
ProposedGlutathione is the main antioxidant made inside cells, recycling between its reduced (GSH) and oxidized (GSSG) forms. Because it is a peptide, much of an oral dose may be broken down in the gut, which is why absorption was long doubted; two trials found blood and immune-cell levels rose with daily use, and liposomal delivery is proposed to protect it. Skin lightening is proposed to come from shifting melanin production toward lighter pheomelanin.[1][3][6][7]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Skin | Grade C | Improved | RCT · n = 124 · 2022 | 2 rows |
| Glutathione levels | Grade C | Improved | RCT · n = 54 · 2015 | 3 rows |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Skin lightening and dark-spot size | Improved | Grade C | RCT · n = 124 · 2022 Asian women Form: glutathione 250 mg with L-cystine 500 mg, vs glutathione alone, cystine alone or placebo · Dose: 250 mg/day glutathione (with or without 500 mg L-cystine) · Duration: 12 weeks The cystine plus glutathione combination lightened skin and shrank dark spots more than placebo and more than either ingredient alone. | 33834608 (opens PubMed)Source [5] |
| Skin melanin index | Improved | Grade C | RCT · n = 60 · 2012 Healthy Thai medical students Form: oral reduced glutathione · Dose: 500 mg/day in two doses · Duration: 4 weeks Melanin index fell at all six sites with glutathione; the difference from placebo was significant at two sites (right face and sun-exposed forearm). | 20524875 (opens PubMed)Source [4] |
| Glutathione levels in blood and cells | Improved | Grade C | RCT · n = 54 · 2015 Healthy non-smoking adults Form: oral reduced glutathione · Dose: 250 or 1,000 mg/day · Duration: 6 months Glutathione rose 30–35% in red cells, plasma and lymphocytes and 260% in cheek cells at 1,000 mg/day; smaller rises at 250 mg/day. Levels returned to baseline 1 month after stopping. Oxidized-to-reduced glutathione ratio fell in both groups. | 24791752 (opens PubMed)Source [1] |
| Oxidative stress markers and glutathione status | No effect | Grade C | RCT · n = 40 · 2011 Adults without acute or chronic disease Form: oral reduced glutathione · Dose: 500 mg twice daily (1,000 mg/day) · Duration: 4 weeks No significant change vs placebo in urinary F2-isoprostanes, 8-OHdG, or red-cell reduced, oxidized or ratio glutathione. | 21875351 (opens PubMed)Source [2] |
| Glutathione levels with liposomal delivery | Improved | Grade D | Open-label trial · n = 12 · 2018 Healthy adults Form: oral liposomal glutathione · Dose: 500 or 1,000 mg/day · Duration: 4 weeks Whole-blood glutathione rose up to 40% and immune-cell (PBMC) glutathione up to 100% by week 2; NK-cell activity markers also rose. | 28853742 (opens PubMed)Source [3] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Reduced glutathione (GSH) capsules | Varies[1] | Two RCTs disagree: blood and cell levels rose over 6 months at 250–1,000 mg/day, but not over 4 weeks at 1,000 mg/day.[1][2] | No treatment-related adverse events reported in the cited trials.[1][2][4] | Raising glutathione stores, skin tone |
| Liposomal glutathione | Varies[3] | One 12-person uncontrolled pilot found blood glutathione rose within 1–2 weeks at 500–1,000 mg/day. No head-to-head trial against plain capsules.[3] | No adverse events reported in the pilot.[3] | Raising glutathione stores |
| Oxidized glutathione (GSSG) | Varies[7] | One 12-week trial found 250 mg/day of either GSH or GSSG tended to lower melanin index vs placebo; no absorption data in our sources.[7] | No serious adverse effects in that trial.[7] | Skin tone |
Studied doses
Doses studied in human trials ranged from 250 to 1,000 mg/day of oral glutathione for 4 weeks to 6 months. Skin trials used 250–500 mg/day; the stores trials used 500–1,000 mg/day.[1][2][3][4][6]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- Medicines
- No published drug interactions for oral glutathione were found in our sources. That is an absence of data, not proof of safety with every medicine.[1][2]
- Asthma and inhaled glutathione
- Nebulized (inhaled) glutathione caused airway narrowing in a small study of people with mild asthma. This applies to inhaled use, not capsules, but people with asthma should know the inhaled form is not the same product.[8]
- Pregnancy and breastfeeding
- No safety trials of glutathione supplements in pregnancy or breastfeeding in our sources.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
How to read the label
- Label dose vs clinical doseCompare the mg of glutathione per serving on your label with the trials: those that measured a rise in body stores used 250–1,000 mg/day for months; the skin trials used 250–500 mg/day for 4–12 weeks.[1][4][6]
- Check reduced vs oxidizedMost trials used reduced glutathione (GSH). The label may say "L-glutathione (reduced)"; oxidized glutathione (GSSG) has only one small skin trial.[1][7]
- Liposomal amounts are glutathione, not liposome weightCompare the mg of glutathione per serving. The liposomal pilot dosed 500–1,000 mg of glutathione, not of the total liquid.[3]
Cost per studied dose, without the sales pitch
Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.
Cost per studied dose
Enter the price, servings and the amount per serving from your label.
Frequently asked questions
Is oral glutathione absorbed?
Partly, according to one 6-month trial that found blood and cell glutathione rose with daily use. A 4-week trial at 1,000 mg/day found no change, so results depend on duration and are not consistent.[1][2]
Is liposomal glutathione better than capsules?
No head-to-head trial in our sources. A 12-person uncontrolled pilot found blood levels rose within 2 weeks on liposomal glutathione, which is promising but weak evidence.[3]
Does glutathione lighten skin?
Small trials in Thai and other Asian participants found modest drops in melanin index at 250–500 mg/day, mostly on sun-exposed skin. Effects were small and long-term safety is unknown.[4][5][6]
How much glutathione was used in studies?
Between 250 and 1,000 mg/day: 250–500 mg/day in skin trials, and 500–1,000 mg/day in trials measuring body stores.[1][2][4][6]
How long until glutathione levels rise?
In the 6-month trial levels were higher at 1, 3 and 6 months and fell back to baseline a month after stopping. The liposomal pilot saw peaks at 2 weeks.[1][3]
What are the side effects of glutathione?
The cited trials reported no treatment-related adverse events over 4 weeks to 6 months. Inhaled glutathione is different and caused airway narrowing in people with asthma.[1][4][8]
Glutathione vs NAC: which raises glutathione?
No head-to-head trials in our sources. NAC supplies cysteine, the building block that limits how fast the body makes glutathione; see the NAC page for its own evidence.[1]
Sources
- [1]Randomized controlled trial of oral glutathione supplementation on body stores of glutathione.. Eur J Nutr, 2015. RCT
- [2]Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers.. J Altern Complement Med, 2011. RCT
- [3]Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function.. Eur J Clin Nutr, 2018. open-label
- [4]Glutathione as an oral whitening agent: a randomized, double-blind, placebo-controlled study.. J Dermatolog Treat, 2012. RCT
- [5]The effects of the oral supplementation of L-Cystine associated with reduced L-Glutathione-GSH on human skin pigmentation: a randomized, double-blinded, benchmark- and placebo-controlled clinical trial.. J Cosmet Dermatol, 2022. RCT
- [6]The clinical effect of glutathione on skin color and other related skin conditions: A systematic review.. J Cosmet Dermatol, 2019. systematic-review
- [7]Glutathione and its antiaging and antimelanogenic effects.. Clin Cosmet Investig Dermatol, 2017. RCT
- [8]Nebulized glutathione induces bronchoconstriction in patients with mild asthma.. Am J Respir Crit Care Med, 1997. RCT
What changed
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Adversarial review pass: every claim re-checked against the cited abstract (or full text where noted), PMIDs re-verified via NCBI esummary, unsupported label-market statements removed, two evidence rows with unreported pooled n removed. Page set indexable.