Supplements › Amino acid or protein

Glutathione

An antioxidant that every cell makes from three amino acids. As a supplement, it has been tested for oxidative stress and for lighter skin.

Strongest evidenceCell healthStrong, 342 studies
Median dose in studies425 mg a dayFrom 24 study groups
Doses in trials by mouth250 to 1,000 mg a dayFor 4 weeks to 6 months.
Judged safe by EFSA300 mg a dayS-acetyl glutathione, adults. Not assessed in pregnancy or breastfeeding.
Ask a doctor or pharmacist first

Ask a doctor or pharmacist first if you:

  • have asthma and plan to inhale glutathione: in 8 people with mild asthma, inhaled glutathione narrowed the airways and caused cough or breathlessness in some of them[1]
  • are pregnant or breastfeeding: EFSA's safety assessment of S-acetyl glutathione did not cover these groups[2]
  • want to give it to a child under 10: the EFSA assessment did not cover this age[2]
  • are offered glutathione into a vein: the FDA knows of at least 30 people with fever, chills, signs of shock or other reactions after injections made from supplement-grade glutathione[3]

Overview

What is glutathione?

Glutathione is a small molecule made of three amino acids: glutamate, cysteine and glycine.[4] Every cell in the body makes it.[5] It is the most abundant antioxidant that the body makes itself.[6] It helps cells remove harmful substances and protects them from oxidation.[5]

Supplements contain plain glutathione in capsules,[7] liposomal or sublingual glutathione,[8][9] or S-acetyl glutathione.[2] In trials, glutathione was also inhaled, given through the nose or given into a vein.[10][11][12]

Does glutathione work?

In some trials it raised glutathione in the blood, but proof of health benefits is limited. In a 6-month trial in 54 healthy adults, 1,000 mg a day raised glutathione by 30% to 35% in red blood cells, plasma and lymphocytes.[6] A 4-week trial of the same daily amount found no change in glutathione or in markers of oxidative damage.[13] A 2026 review concluded that research supports how glutathione works in the body more than a proven treatment effect.[9]

For skin, 5 randomized trials found lighter skin with 250 to 500 mg a day by mouth.[14] For immune support, one trial measured natural killer cells, a type of immune cell. After 3 months of 1,000 mg a day, they worked more than twice as well as with placebo.[6] In cystic fibrosis, a Cochrane review found that inhaled and oral glutathione appear to improve lung function.[10] For the liver, one small study without a placebo group found a lower level of ALT, a liver enzyme.[15] For detox, one trial of a yeast extract with 50 mg of glutathione found less acetaldehyde in the blood after alcohol, but no difference in hangover symptoms.[16]

Is glutathione safe?

Taken by mouth, it caused few problems in trials. In a 4-week skin trial, both glutathione and placebo were very well tolerated.[7] A review of skin studies found some adverse events, none of them serious.[17] EFSA judged S-acetyl glutathione safe for adults at up to 300 mg a day. Its assessment did not cover pregnant or breastfeeding women or children under 10.[2]

Other forms carry more risk. In a study of 8 people with mild asthma, inhaled glutathione narrowed the airways.[1] A 2025 review advised against glutathione into a vein for skin lightening, because it did not work and caused side effects.[14] In 2026, the FDA reported at least 30 people with fever, chills, signs of shock and other reactions after glutathione injections made from supplement-grade glutathione.[3]

Ask a doctor or pharmacist first if you are pregnant or breastfeeding, or if you have asthma and plan to inhale glutathione.[2][1]

How it works

Glutathione is a small molecule made of three amino acids: glutamate, cysteine and glycine.[4] It is the most abundant antioxidant that the body makes itself.[6] Enzymes in the gut and liver break down most of a swallowed dose.[18] Still, in a 6-month trial, a daily dose by mouth raised glutathione in the blood.[6]

  1. Made in cells

    Every cell makes glutathione in two steps, each with its own enzyme. How much a cell makes depends mostly on its supply of cysteine and on the first enzyme, glutamate cysteine ligase.[5] Oxidative stress makes cells produce more of these enzymes.[5]

  2. Gut breakdown

    An enzyme in the gut and the liver, gamma-glutamyltransferase, splits swallowed glutathione into its amino acids.[18] In 7 healthy people, one dose of about 3 g did not raise glutathione in the blood over the next 4.5 hours.[18]

  3. Body stores

    Daily use did raise levels. In a trial of 54 adults, 1,000 mg a day for 6 months raised glutathione by 30% to 35% in red blood cells, plasma and lymphocytes, a type of white blood cell. Levels went back to the starting point 1 month after people stopped.[6]

  4. Antioxidant work

    Glutathione and its oxidized form, glutathione disulfide, are the main pair that keeps the balance between oxidation and reduction in cells.[4] Glutathione helps cells remove harmful substances, protects them from oxidation and takes part in the immune response.[5][4]

  5. Skin pigment

    In skin, glutathione blocks tyrosinase, the enzyme that makes melanin. It also shifts production from dark eumelanin to lighter phaeomelanin.[19][20]

Benefits and studies

Each row is one benefit. The square shows the grade and the number of studies. Open a row to see the most trusted studies.

StrongModerateWeakNo trials
BenefitMain effects in studiesStudiesPeople

Dose

Trials of glutathione by mouth gave 250 to 1,000 mg a day.[6][13][14] The body makes glutathione itself, and enough protein in the diet helps it keep normal levels.[4]

Usual dose

For blood levels, trials gave 250 or 1,000 mg a day, and the higher dose raised levels more.[6] For skin colour, trials gave 250 mg once or twice a day, or 500 mg once a day.[14] One small fatty liver study gave 300 mg a day.[15]

Form

Trials in healthy adults gave plain glutathione by mouth,[6][13] for example as capsules.[7] Liposomal and sublingual (under the tongue) forms may make glutathione more stable and easier to take up, but proof of better health effects is limited.[9] S-acetyl glutathione is another form, assessed by EFSA for use in food supplements.[2] In hospital trials, doctors gave glutathione into a vein.[12][21]

How long

Blood levels rose after 1 week of liposomal glutathione[8] and after 1 month of plain glutathione.[6] They went back to the starting point 1 month after people stopped.[6] Skin trials lasted 4 to 12 weeks.[7][20]

Safe intake

EFSA judged S-acetyl glutathione safe for adults at up to 300 mg a day, and for teenagers at 190 to 269 mg a day, by age. Its assessment did not cover children under 10 or pregnant and breastfeeding women.[2] Plain glutathione at 1,000 mg a day was given for 6 months in one trial.[6] Ask a doctor or pharmacist first if you are pregnant or breastfeeding.[2]

Doses in studies

Most studies gave 100 to 250 mg a day, for 1 to 3 months.

The counts are study groups. A study group is one set of people in a study who took the same dose. One study can have several groups. These are amounts from studies, not advice for you.

How much a day24 groups in 19 studies
  1. Up to 25 mg1 group
  2. 25 to 50 mg2 groups
  3. 50 to 100 mg0 groups
  4. 100 to 250 mg8 groups
  5. 250 to 500 mg7 groups
  6. 500 to 1,000 mg3 groups
  7. 1,000 to 2,500 mg3 groups
For how long25 groups in 20 studies
  1. 1 week or less3 groups
  2. 1 to 4 weeks7 groups
  3. 1 to 3 months11 groups
  4. 3 to 6 months4 groups
  5. 6 to 12 months0 groups
  6. More than a year0 groups
Half of the groups took less than 425 mg a day. Half took more.Half of the groups took 200 to 625 mg a day. A quarter took less, a quarter took more.6 of 24 groups took 500 mg a day or more. Do not copy a study dose without a doctor.

Taken together

9 of 25 study groups took glutathione with something else. This shows what studies gave together, not what works together.

  1. Citrulline4 studies4
Bars and numbers count study groups. A companion is shown only when at least 3 different studies gave it.

Protocols

What studies used when they gave glutathione for one goal, or to a group of people.

Each protocol describes what studies used, for one goal or for one group of people. It is not advice for you: talk to a doctor before you start a supplement.

Questions

12 questions in 4 groups. Open one for the short answer; each has its own page with the full answer and sources.

Basics
Is glutathione absorbed when taken by mouth?

Partly. Enzymes in the gut and liver break swallowed glutathione down, and one large dose did not raise its level in the blood.[18] But in a 6-month trial, 250 or 1,000 mg a day did raise glutathione in the blood.[6] A 4-week trial of 1,000 mg a day found no rise.[13]

Read the full answer ›
Do glutathione levels fall with age?

In the blood, mostly yes. A 2023 review found 16 studies of blood: most of them reported less glutathione at older ages, except in the very oldest people. Studies of the brain did not agree as clearly.[22]

In a small trial, 24 older adults had less glutathione than 12 young adults. In those who took glycine with NAC (N-acetylcysteine), a source of cysteine, for 16 weeks, glutathione levels improved.[23] The review noted that the effect of raising brain glutathione on brain decline has been little studied.[22]

Open the answer with sources ›
Benefits
Does glutathione lighten skin?

Trials suggest a modest effect. A 2025 systematic review found 5 randomized trials in which glutathione by mouth, 250 to 500 mg a day, lowered the melanin index, a measure of skin pigment, more than placebo. The same review advised against glutathione into a vein, which lacked effect and caused side effects.[14] An older review called the evidence inconclusive.[17]

Read the full answer ›
Does glutathione help the liver?

The evidence is thin. In one small study without a placebo group, 29 people with fatty liver took 300 mg a day for 4 months, and their liver enzyme ALT fell.[15] In a trial in hepatitis B, glutathione into a vein, added to an antiviral medicine, improved liver tests more than the antiviral alone.[21]

Read the full answer ›
Does glutathione help the body detox?

Glutathione is part of how cells remove harmful substances.[5] For detox, a crossover trial in 40 adults found that a yeast extract with 50 mg of glutathione lowered acetaldehyde, a product of alcohol breakdown, in the blood after drinking. Hangover symptoms did not differ from placebo.[16] Three of the authors worked for Samyang Corp., a food company.[16]

Glutathione into a vein has been used to treat acute poisoning.[15]

Open the answer with sources ›
Does glutathione help Parkinson's disease?

Trials so far found no clear benefit. A 2026 review covered 9 studies of NAC and glutathione with 196 people. Glutathione given through the nose raised brain levels only a little and did not significantly improve symptoms.[24] In a 3-month trial in 45 people, 100 or 200 mg through the nose 3 times a day was no better than placebo. All groups improved, including the placebo group.[11] In a 4-week pilot trial in 21 people, glutathione into a vein did not change symptom scores more than placebo.[25]

In the same 2026 review, NAC improved symptoms, but the authors called the evidence for both early.[24]

Open the answer with sources ›
Does glutathione help people with cystic fibrosis?

It may help a little, together with usual treatment. A 2019 Cochrane review found 2 studies of inhaled glutathione with 258 people. It probably improved FEV1, the air a person can breathe out in 1 second, by 3.5 percentage points of the expected value at 3 months, but not clearly at 6 months.[10] The review said that firm conclusions need larger and longer studies.[10]

A trial included 44 children aged 18 months to 10 years. They took glutathione by mouth, 65 mg per kg of body weight a day in 3 doses at meals, or placebo. After 6 months, glutathione had improved weight, BMI and height more than placebo.[26]

Open the answer with sources ›
Safety
Are glutathione injections safe?

They can cause harm. A 2025 review of skin studies advised against glutathione into a vein, because it lacked effect and caused side effects.[14] In 2026, the FDA reported at least 30 people with fever, chills, signs of shock and other reactions after glutathione injections made from supplement-grade glutathione. Some went to hospital.[3]

Read the full answer ›
Is inhaled glutathione safe for people with asthma?

It can narrow the airways. In 8 people with mild asthma, 600 mg of inhaled glutathione lowered FEV1, the air a person can breathe out in 1 second, by 19%. Salt water lowered it by 1%. 4 people coughed and 3 felt short of breath. Inhaled salbutamol taken first prevented this. The authors think that sulfite formed from glutathione caused it.[1]

In people with cystic fibrosis, a Cochrane review found that inhaled glutathione may make little or no difference to adverse events.[10]

Open the answer with sources ›
Can you take glutathione during pregnancy?

Its safety in pregnancy has not been shown. In 2026, EFSA judged S-acetyl glutathione safe for adults at up to 300 mg a day, but its assessment did not cover pregnant or breastfeeding women.[2] No trial of glutathione supplements in pregnant women was found in PubMed. Ask a doctor or pharmacist first if you are pregnant or breastfeeding.[2]

Open the answer with sources ›
Forms and timing
Is liposomal glutathione better than regular glutathione?

It is not known. No trial in PubMed has compared liposomal glutathione with plain capsules directly. Plain glutathione by mouth, 1,000 mg a day, raised glutathione by 30% to 35% in red blood cells, plasma and lymphocytes after 6 months.[6] Liposomal glutathione raised it by up to 40% in whole blood after 2 weeks, in a study of 12 people paid for by a company that supplies it.[8]

A 2026 review said that liposomal and sublingual forms may make glutathione more stable, but that proof of real health benefits is limited.[9] In one small trial, sublingual glutathione raised plasma glutathione more than plain glutathione by mouth.[27]

Open the answer with sources ›
Is NAC better than glutathione?

It depends on the goal. NAC (N-acetylcysteine) supplies cysteine, one of the main factors that decide how much glutathione cells make.[4][5] A 3-week crossover trial in 20 people with metabolic syndrome compared sublingual glutathione, plain glutathione by mouth and NAC. Sublingual glutathione raised plasma glutathione more than plain glutathione by mouth, and the authors judged it better than both plain glutathione by mouth and NAC.[27]

In Parkinson's disease, a 2026 review found that NAC improved symptoms, while glutathione given through the nose did not. It called the evidence for both early.[24] In cystic fibrosis, NAC by mouth probably improved lung function after 6 months.[10]

Open the answer with sources ›

References

  1. Nebulized glutathione induces bronchoconstriction in patients with mild asthma. Marrades RM, Roca J, Barberà JA, de Jover L, MacNee W, Rodriguez-Roisin R Am J Respir Crit Care Med, 1997. PMID 9279219
  2. Safety of S-acetyl glutathione as an novel food pursuant to Regulation (EU) 2015/2283. Turck D, Bohn T, Cámara M, Castenmiller J, De Henauw S, Jos Á, et al. EFSA J, 2026. PMID 42683004
  3. FDA reminds compounders not to use dietary supplement grade glutathione for injectables. US Food and Drug Administration, 2026. www.fda.gov
  4. Glutathione metabolism and its implications for health. Wu G, Fang YZ, Yang S, Lupton JR, Turner ND J Nutr, 2004. PMID 14988435
  5. Regulation of glutathione synthesis. Lu SC Mol Aspects Med, 2009. PMID 18601945
  6. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Richie JP Jr, Nichenametla S, Neidig W, Calcagnotto A, Haley JS, Schell TD, et al. Eur J Nutr, 2015. PMID 24791752

Review history

  1. 10 Nov 2026CheckedReviewerChecked every claim against its source.
  2. 10 Nov 2026Page createdResearcherFirst edition, written from PubMed and public health sources.