✓ No active regulatory warningsFDA MedWatch, EMA EudraVigilance, WHO VigiBase, WADA Prohibited List · 2026-05-29
📰Read the full Glutathione evidence review on GMJ News →Complete clinical article, references and updates on news.gmj.ge. This page is the structured safety summary.⚠ Cancer patient self-supplementing GSH — may protect tumor cells from chemotherapy; discuss with oncologist [1]
⚠ Patient choosing oral GSH over NAC — NAC may be more effective for intracellular GSH synthesis [2]
⚠ Acetaminophen overdose — IV NAC (not oral GSH) is the standard of care for GSH repletion [2]
⚠ Elderly with chronic disease + low GSH — combination of NAC + glycine (GlyNAC) is an emerging approach [1]
ℹ️ Not obtained from food. Made by the body and poorly absorbed from food; there is no daily dietary target.
☑ Risk checker
Chronic liver disease (impaired synthesis) [1]
HIV/AIDS (increased oxidative stress and GSH consumption) [1]
Aging (synthetic capacity declines) [1]
Chronic alcoholism (acetaldehyde conjugation depletes GSH) [2]
Acetaminophen overdose (NAPQI conjugation depletes GSH) [2]
Chronic inflammatory conditions (increased oxidative demand) [1]
Poor protein intake (insufficient cysteine, glycine, glutamate) [2]
Select factors
🔬 Lab interpreter
Recommended test
Blood glutathione (reduced GSH and oxidized GSSG)
Blood glutathione (reduced GSH and oxidized GSSG)
Reference range / target
High GSH:GSSG ratio (>90:10)
High GSH:GSSG ratio (>90:10)
Reflects systemic redox status. Low GSH or low GSH:GSSG ratio indicates oxidative stress [1].
Full lab monitoring ↓⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
Glutathione is the master intracellular antioxidant but oral bioavailability is the Achilles heel — standard oral GSH is extensively degraded. NAC (600–1,200 mg/day) is generally more effective at raising intracellular GSH because it provides the rate-limiting cysteine substrate. If supplementing GSH directly, use liposomal or S-acetyl forms. Do NOT supplement during chemotherapy without oncologist guidance [1] [2] [3].
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: See guidance
GSH is naturally present in all cells. No specific oral GSH supplementation data in pregnancy. NAC (Category B) is better studied for raising GSH in pregnancy [2].
👦 Pediatric: See guidance
No established pediatric dose for oral GSH supplementation. Children synthesize GSH normally from dietary amino acids. NAC is used in pediatrics for acetaminophen overdose and as mucolytic [2].
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Standard dose
How to take
🍽 Timing: Take on empty stomach for best absorption (if using oral GSH) [3].
💊 With food: Empty stomach preferred for oral GSH. NAC also best on empty stomach [2].
2 Which form?
| Form | Bioavailability | Vegan | Cost |
|---|---|---|---|
| ['Reduced L-glutathione (standard)', 'common', 'The active thiol form. Oral bioavailability is limited by GGT degradation in the gut and liver. Some studies show modest plasma GSH increases at 500–1,000 mg/day [3].'] | Standard | Check label | |
| ['Liposomal glutathione', 'preferred', 'Encapsulated in phospholipid vesicles to bypass GI degradation. Higher plasma levels than standard oral GSH. More expensive [3].'] | Standard | Check label | |
| ['S-Acetyl glutathione', '', 'Acetylated form resistant to GGT degradation. Crosses cell membranes and is deacetylated intracellularly. Emerging evidence for better intracellular delivery [3].'] | Standard | Check label | |
| ['IV glutathione', '', 'Bypasses GI tract entirely. Used clinically in Parkinson disease research and in some integrative medicine protocols. Not available OTC [3].'] | Standard | Check label | |
| ['NAC (as precursor)', 'preferred', 'N-Acetylcysteine provides the rate-limiting cysteine for endogenous GSH synthesis. May be more effective than oral GSH for raising intracellular levels [2].'] | Standard | Check label |
3 Common questions
Is oral glutathione effective? ▼
This is the central debate. Standard oral GSH is extensively degraded by GGT in the gut. However, a 2015 RCT showed that 500–1,000 mg/day oral GSH for 6 months modestly increased blood GSH [5]. Liposomal and S-acetyl forms may improve delivery. Many clinicians prefer NAC (600–1,200 mg/day) as it provides the rate-limiting cysteine for cells to synthesize their own GSH [2] [3].
Is NAC better than glutathione supplements? ▼
Arguably yes for raising intracellular GSH, because NAC provides cysteine — the rate-limiting substrate — and cells synthesize GSH where it's needed (intracellularly). Oral GSH must survive GI degradation and cross cell membranes intact [2]. However, liposomal GSH may offer advantages for direct GSH delivery, particularly in individuals with impaired synthetic capacity.
Why does glutathione decline with age? ▼
GSH synthetic capacity decreases with aging due to reduced activity of glutamate-cysteine ligase (the rate-limiting enzyme) and reduced cysteine availability. By age 80, GSH levels may be 50% of young adult levels [1]. This decline is associated with increased oxidative stress and disease susceptibility.
Does glutathione lighten skin? ▼
Some small trials in Southeast Asia showed that oral GSH (500 mg/day) reduced melanin index, leading to lighter skin tone [3]. This is due to GSH's inhibition of tyrosinase. This is NOT a medical indication and raises ethical questions about skin-lightening marketing. The cosmetic industry has promoted this use aggressively in some markets.
4 Clinical evidence
Strong
Glutathione is the master intracellular antioxidant — depletion is associated with oxidative stress in virtually every chronic disease (liver disease, HIV, COPD, diabetes, neurodegeneration) [1]. IV glutathione acutely raises plasma and tissue GSH levels [3]. NAC (as precursor) effectively raises intracellular GSH — this is the basis for its use as the acetaminophen overdose antidote [2]. HIGH
Moderate
Oral glutathione: a randomized trial (n = 54) showed that 250–1,000 mg/day oral GSH for 6 months modestly increased blood GSH levels and reduced oxidative stress markers [5]. Liposomal GSH: small studies show superior plasma elevation compared to standard oral GSH [3]. Skin lightening: oral GSH has been marketed for skin whitening (melanogenesis inhibition), with some small positive trials — this is controversial and not a medical indication [3]. NAFLD: small trials of oral GSH or IV GSH show improved liver markers [3]. MODERATE
Insufficient
Parkinson disease: IV GSH has been studied in pilot trials with mixed results [3]. Cancer adjunct: theoretical (GSH depletion in cancer cells) but clinical data are lacking and GSH could theoretically protect tumor cells too [1]. Anti-aging: theoretical based on age-related GSH decline but no outcome trials [1]. Athletic performance: limited and inconsistent data [3]. Autism: some pilot studies of GSH-related interventions, insufficient for recommendation [3]. LOW
5 Safety, toxicity & adverse events
Relative
⚠ Asthma — inhaled forms may trigger bronchospasm (caution by analogy)
⚠ Sulfur sensitivity
⚠ Pregnancy and lactation — insufficient safety data
🚩 Red flags
● Cancer patient supplementing GSH without oncologist knowledge — potential interference with chemotherapy [1]
● Patient spending money on standard oral GSH when NAC would be more effective and cheaper [2]
● IV glutathione 'drip bar' without medical supervision — unregulated, infection risk, uncertain benefit [3]
6 Interactions
Drug interactions
Chemotherapy agents (general) Major
Mechanism: GSH conjugation is a major detoxification pathway for many chemotherapy drugs. Supplemental GSH may reduce drug efficacy by protecting tumor cells. [1]
Effect: Potential reduced chemotherapy efficacy. [1]
Action: Do NOT supplement GSH during active chemotherapy without oncologist approval [1].
Supplement synergies
NAC · 600–1,200 mg/day NAC
NAC provides cysteine — the rate-limiting substrate for GSH synthesis. NAC + direct GSH covers both synthesis and direct supplementation [2].
NAC provides cysteine — the rate-limiting substrate for GSH synthesis. NAC + direct GSH covers both synthesis and direct supplementation [2].
Glycine + NAC (GlyNAC) · 1.2 g NAC + 1.2 g glycine BID
GlyNAC provides both rate-limiting substrates (cysteine + glycine). A 2021 RCT in older adults showed GlyNAC reversed GSH deficiency and oxidative stress markers [1].
GlyNAC provides both rate-limiting substrates (cysteine + glycine). A 2021 RCT in older adults showed GlyNAC reversed GSH deficiency and oxidative stress markers [1].
Vitamin C · 500–1,000 mg/day
Vitamin C recycles oxidized glutathione (GSSG) back to reduced GSH. Synergistic antioxidant cycle [1].
Vitamin C recycles oxidized glutathione (GSSG) back to reduced GSH. Synergistic antioxidant cycle [1].
7 Regulatory
United States (FDA): Classified as a dietary supplement. No FDA-approved health claims. IV glutathione is used off-label in integrative medicine [3].
European Union (EFSA): Available as food supplement. No authorized health claims for oral GSH [3].
Japan (MHLW): Glutathione injection is an approved pharmaceutical (Tathione) for liver disorders and chemotherapy-induced toxicity [3].
South Korea / Philippines: Oral and IV GSH widely marketed for skin lightening. Regulatory concern about unregulated IV glutathione 'drip bars' [3].
8 US supplement products
124
on-market products containing Glutathione (NIH DSLD)
Brands carrying Glutathione (56)
Click a brand to see its Glutathione products.
9 Frequently paired with
10 Cite this page
Vancouver: Pkhakadze G. Glutathione — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Aug 15]. Available from: https://supplement.ge/ingredients/glutathione/
APA 7th: Pkhakadze, G. (2026). Glutathione — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/glutathione/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Institution: Public Health Institute of Georgia (PHIG)
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: February 2027
References: 5 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "Glutathione — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/glutathione/ CC BY 4.0.
GP
Prof. G. Pkhakadze, MD, MPH, PhD
Professor of Public Health · Head of Department, DTMU
Editor-in-Chief, Georgian Medical Journal (ISSN 3088-4322)
Chair, Public Health Institute of Georgia · UEMS Public Health Section
Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG