What is Glutathione?
Licensed Pharmacist · Medical Writer & Medical Reviewer
Patricia Weiser is a licensed Pennsylvania pharmacist, independent health content writer, and medical reviewer with more than 15 years of pharmacy experience across community and hospital settings. Her clinical background gives her a practical understanding of medication use, patient counseling, drug safety, and the questions patients and caregivers commonly encounter.
Glutathione is a three-amino-acid peptide made by cells and involved in redox regulation, peroxide metabolism, conjugation of reactive compounds so cells can process them, and a range of other cellular activities. While glutathione is essential, that doesn’t necessarily mean glutathione supplements are beneficial for everyone.
Below, we’ll look at what glutathione does inside cells, what supplementation has and has not been shown to change, and where the regulatory picture stands.
At a Glance
- Glutathione is a substance your body naturally makes inside its cells. It is made from three amino acids and plays an important role in protecting cells and processing certain substances.
- Low glutathione levels have been found in people with a number of chronic diseases. However, researchers often do not know whether low glutathione contributes to the disease or is a result of it.
- There is no standard medical test or widely accepted diagnosis for a general “glutathione deficiency” in otherwise typical clinical care.
- Compounded injectable glutathione products are not FDA-approved. How glutathione is taken also matters because the risks and regulations differ between oral supplements and injections.
- As of September 2026, the FDA is investigating adverse events linked to compounded IV glutathione made with inappropriate supplement-grade ingredients, including concerns about endotoxin contamination [1].
What glutathione is
Glutathione is a natural substance made by cells throughout the body. It is built from three amino acids (glutamate, cysteine, and glycine) and plays an important role in protecting cells and helping the body process certain substances [2,3].
Your cells make most of the glutathione they use rather than relying on glutathione directly from food. The body needs enough of its building blocks, particularly the amino acid cysteine, to produce it[2].
Glutathione can exist in different chemical forms as it carries out its functions. Researchers sometimes measure these forms to study oxidative stress and how cells are functioning [4]. These laboratory measurements, however, do not necessarily tell us whether taking a glutathione product will improve a person’s symptoms, health, or overall well-being.
What glutathione does in the body
Glutathione’s main jobs are as a helper molecule for enzymes, and several enzyme families cannot operate without it.
- Glutathione peroxidases use glutathione to reduce hydrogen peroxide and lipid and organic hydroperoxides, converting them into less reactive products [2].
- Glutathione S-transferases catalyze the attachment of glutathione to electrophilic and reactive compounds, including many xenobiotics, so that cells can process and eliminate them [5]. This enzymatic conjugation is what “detoxification” means biochemically. Glutathione does not flush toxins out of the body in any general sense.
- Glutathione supports other redox systems and helps maintain protein-thiol homeostasis, keeping sulfur-containing groups on proteins in appropriate states [2].
- It also participates in cell signaling, iron handling, protein folding, apoptosis, and other cellular processes [4].
“Antioxidant” and “detox” describe specific enzyme-dependent chemistry inside cells, but not a general cleansing effect that a supplement can be assumed to deliver.
The clearest clinical example: acetaminophen overdose
One of the clearest examples of glutathione’s importance is acetaminophen overdose. Normally, glutathione helps the liver safely process a toxic byproduct of acetaminophen. But after a large overdose, the liver can run out of enough glutathione to keep up, which can lead to serious liver damage [6].
The standard treatment for acetaminophen overdose is N-acetylcysteine (NAC) in intravenous (IV) form or by mouth [7]. NAC helps the body rebuild its glutathione supply and may protect the liver in other ways as well [6].
This example shows that glutathione is important to normal liver function. However, it does not show that taking glutathione supplements or receiving IV glutathione provides health benefits for people who have not overdosed on acetaminophen.
Why people take glutathione
People take glutathione supplements for many different reasons. Common claims include antioxidant support, “detox,” immune support, exercise recovery, anti-aging, and skin lightening.
The evidence is not equally strong for all of these uses. Results can also differ depending on how glutathione is taken, the dose used, and who is taking it. A benefit seen in one type of study does not necessarily mean glutathione will help with a different condition or in a different form.
We cover the evidence for specific uses separately in our guide to glutathione benefits.
How glutathione is sold
Glutathione is available in several forms, including capsules and tablets, liposomal and sublingual products, topical creams and serums, inhaled products, and compounded injections or IV preparations. NAC is also sometimes discussed alongside glutathione because it provides cysteine, one of the building blocks the body uses to make glutathione.
However, the FDA has not approved glutathione supplements or compounded glutathione products [8].
It is still unclear how reliably oral glutathione supplements increase glutathione levels in the body. One six-month study in 54 healthy adults found that oral supplementation increased glutathione stores, while a shorter four-week study found no significant change [9,10]. A study of 12 adults also found increases after taking liposomal glutathione, but the study was too small to draw firm conclusions and had no comparison group, so it cannot say whether liposomal glutathione is better absorbed than standard oral forms [11].
Low glutathione: depletion is not the same as deficiency
Glutathione levels can be low in certain medical situations, but that is not the same as having a recognized condition called “glutathione deficiency.” There is no standard blood test or accepted reference range used to diagnose a general glutathione deficiency in routine medical care.
Glutathione depletion is well documented in some specific situations, including acetaminophen overdose [6]. Lower or altered glutathione levels have also been reported in conditions such as HIV, cystic fibrosis, critical illness, heavy alcohol use, and rare inherited disorders that affect glutathione production [4].
Researchers have also found lower glutathione levels in people with conditions such as type 2 diabetes, fatty liver disease, and some neurodegenerative diseases, as well as with aging [2,4]. However, these findings do not necessarily mean that low glutathione causes these conditions. In many cases, it is unclear whether lower levels are a cause, a result of the disease, or simply associated with it.
Just as importantly, raising a glutathione level on a lab test does not automatically mean that a person’s health or symptoms will improve.
Doses studied
Below is a summary of two trials of glutathione.
| Study | Population | Route | Exposure | Duration | Outcome measured |
|---|---|---|---|---|---|
| Richie et al., 2015 [9] | 54 healthy nonsmoking adults, randomized | Oral (standard) | Placebo, 250 mg/day, or 1,000 mg/day | 6 months | Body glutathione stores |
| Sinha et al., 2018 [11] | 12 healthy adults (pilot) | Oral (liposomal) | 500 or 1,000 mg/day | 1 month | Body stores, immune markers |
In a 2015 randomized trial, the higher-dose group had increased glutathione stores after six months [9]. However, the study measured glutathione levels, not whether participants felt better or had improved health outcomes.
A smaller 2018 pilot study also reported increases in glutathione stores, but it used a different formulation and study design [11]. Because the studies were small and differed in important ways, they cannot be directly compared.
Side effects and safety
The safety of glutathione depends partly on how it is taken. Oral supplements, inhaled products, and IV or injectable products should not be assumed to have the same risks.
Oral glutathione has generally been well tolerated in small, short-term studies. Reported side effects have included digestive symptoms such as cramping, bloating, or loose stools [9,11]. However, long-term safety is not well established, and studies in healthy adults do not tell us as much about safety in people with serious medical conditions.
People living with chronic conditions should discuss the safety of glutathione products with their care team. For instance, inhaled glutathione may be unsafe for people with asthma. In one small study of eight people with mild asthma, nebulized glutathione caused significant narrowing of the airways [12].
People undergoing cancer treatment should also use caution with antioxidant supplements. Research on antioxidants during radiation therapy has produced mixed results, and it is not clear whether glutathione specifically affects treatment outcomes [13]. Anyone receiving cancer treatment should discuss glutathione or other antioxidant supplements with their oncology team.
There is also not enough good-quality human research to establish the safety of glutathione supplements during pregnancy or breastfeeding. That means the evidence is limited, not that harm has been proven.
When to talk to your healthcare provider
It is especially important to talk with a healthcare professional before using glutathione if you are considering injections or IV treatment, are pregnant or breastfeeding, are receiving cancer treatment, take multiple medications, have a serious chronic health condition, or have asthma and are considering an inhaled product.
More generally, it is a good idea to check with your healthcare provider before starting any new supplement, including glutathione.
Regulatory status
As of September 2026, oral glutathione products are sold in the U.S. as dietary supplements. Like other dietary supplements, they are not FDA-approved for safety or effectiveness before they are sold and are not approved to treat or prevent disease [8].
Compounded glutathione injections are also not FDA-approved. The FDA does not review compounded drugs for safety, effectiveness, or quality before they are marketed [8,14].
In August 2026, the FDA reported adverse events in at least 30 people who received compounded IV glutathione products made with supplement-grade glutathione that was not appropriate for injectable use. Two related recalls also involved elevated levels of bacterial endotoxins [1].
These reports raise concerns about how some compounded IV products were made. They do not suggest that all glutathione products are unsafe.
Conclusion
Glutathione is an important substance that your body makes naturally, and its role inside cells is well established. What is much less certain is whether taking glutathione as a supplement improves health.
Low glutathione levels can occur in some medical conditions, but that is not the same as having a recognized glutathione deficiency. And even when a supplement raises glutathione levels in the body, that does not necessarily mean it improves symptoms or overall health.
The key is to separate what we know about glutathione’s normal role in the body from what has actually been proven about glutathione products.
Frequently Asked Questions
Yes. On supplement labels, “L-glutathione” and “glutathione” generally refer to the same compound.
Glutathione is none of those exactly. It is a tripeptide, which means it is made from three amino acids: glutamate, cysteine, and glycine [2].
Some foods contain glutathione, but your body also makes its own. Your cells use amino acids from the diet, especially cysteine, to help produce glutathione [2].
Glutathione levels can be measured in research and some specialized laboratory settings [4]. However, there is no standard blood test or widely accepted reference range used to diagnose a general “glutathione deficiency” in routine medical care. This is different from rare inherited disorders that affect glutathione production, such as glutathione synthetase deficiency.
Information about glutathione interactions is limited, and the risks may depend on how it is taken and what medications a person uses. There is particular uncertainty around antioxidant supplements during cancer treatment, so people receiving chemotherapy or radiation therapy should discuss glutathione with their oncology team [13].
There is not enough good-quality human research to know whether glutathione supplements are safe during pregnancy or breastfeeding. That does not mean they have been shown to cause harm; it means the evidence is not strong enough to establish safety.
References
- U.S. Food and Drug Administration. FDA reminds compounders not to use dietary supplement grade glutathione for injectables. August 27, 2026. https://www.fda.gov/drugs/human-drug-compounding/fda-reminds-compounders-not-use-dietary-supplement-grade-glutathione-injectables
- Maher P. Glutathione and glutathione-dependent enzymes: From biochemistry to gerontology and successful aging. Ageing Research Reviews. 2023. PMID:37683986. https://pubmed.ncbi.nlm.nih.gov/37683986/
- Gasmi A, Nasreen A, Lenchyk L, et al. An Update on Glutathione’s Biosynthesis, Metabolism, Functions, and Medicinal Purposes. Current Medicinal Chemistry. 2024. doi:10.2174/0109298673251025230919105818. PMID:37921175. https://doi.org/10.2174/0109298673251025230919105818
- Ballatori N, Krance SM, Notenboom S, et al. Glutathione dysregulation and the etiology and progression of human diseases. Biological Chemistry. 2009;390(3):191-214. doi:10.1515/BC.2009.033. PMID:19166318. https://doi.org/10.1515/BC.2009.033
- Aloke C, Onisuru OO, Achilonu I. Glutathione S-transferase: A versatile and dynamic enzyme. Biochemical and Biophysical Research Communications. 2024;734:150774. doi:10.1016/j.bbrc.2024.150774. PMID:39366175. https://doi.org/10.1016/j.bbrc.2024.150774
- Chiew AL, Isbister, GK. Advances in the understanding of acetaminophen toxicity mechanisms: a clinical toxicology perspective. Expert Opinion on Drug Metabolism & Toxicology. 2023. doi:10.1080/17425255.2023.2259787. PMID:37714812. https://doi.org/10.1080/17425255.2023.2259787
- Dart RC, Mullins ME, Matoushek T, et al. Management of Acetaminophen Poisoning in the US and Canada: A Consensus Statement. JAMA Network Open. 2023;6(8). doi:10.1001/jamanetworkopen.2023.27739. PMID:37552484. https://doi.org/10.1001/jamanetworkopen.2023.27739
- U.S. Food and Drug Administration. 10 Facts about What FDA Does and Does Not Approve / Is It Really FDA Approved? Current FDA consumer information. https://www.fda.gov/consumers/consumer-updates/10-facts-about-what-fda-does-and-does-not-approve
- Richie JP Jr, Nichenametla S, Neidig W, et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. European Journal of Nutrition. 2015;54(2):251-263. doi:10.1007/s00394-014-0706-z. PMID:24791752. https://doi.org/10.1007/s00394-014-0706-z
- Allen J, Bradley RD. Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers. Journal of Alternative and Complementary Medicine. 2011. PMID:21875351. https://pubmed.ncbi.nlm.nih.gov/21875351/
- Sinha R, Sinha I, Calcagnotto A, et al. Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function. European Journal of Clinical Nutrition. 2018;72(1):105-111. doi:10.1038/ejcn.2017.132. PMID:28853742. https://doi.org/10.1038/ejcn.2017.132
- Marrades RM, Roca J, Barberà JA, et al. Nebulized glutathione induces bronchoconstriction in patients with mild asthma. American Journal of Respiratory and Critical Care Medicine. 1997;156(2 Pt 1):425-430. doi:10.1164/ajrccm.156.2.9611001. PMID:9279219. https://doi.org/10.1164/ajrccm.156.2.9611001
- Limbrunner J, Doerfler J, Pietschmann K, et al. The influence of antioxidant supplementation on adverse effects and tumor interaction during radiotherapy. Clinical and Experimental Medicine 2025. PMID:40691411. doi:10.1007/s10238-025-01804-x. https://doi.org/10.1007/s10238-025-01804-x
- U.S. Food and Drug Administration. Compounding and the FDA: Questions and Answers. https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers