NAC vs Glutathione: Which Question Each Answers
NAC and glutathione are not rivals: one is a medicine and a building-block supplement, the other the body's own molecule. See what trials show about blood levels and safety.
Content last updated . This page has not been medically reviewed.
Urgent first: overdose and poisoning
If someone may have taken too much acetaminophen (also called paracetamol) or any other medicine or supplement, call Poison Help at 1-800-222-1222 (US), or 911 in an emergency. Do not try to treat an overdose with a supplement. Clinicians sometimes use acetylcysteine to treat acetaminophen overdose; it is not a home remedy. [1] Other countries: Poison Help by country and poisoning: what to do first.The short answer
"NAC or glutathione?" mixes up two different questions. Glutathione is a molecule your cells make. N-acetylcysteine (NAC) is a compound used both as a medicine and as a supplement, studied partly because the body needs the amino acid cysteine to make glutathione. A supplement that raises a blood marker is not the same as one that improves health, and we found no trial that compared NAC and glutathione supplements on a health outcome. There is no universal winner. Information only, not advice.What each one is
Glutathione is present in all mammalian tissues as the most abundant non-protein thiol that defends against oxidative stress, and a 2013 review says its production depends on the availability of the sulfur amino acid cysteine. [2] Trial authors describe glycine and cysteine as the amino acids required to make glutathione, a three-part molecule (a tripeptide). [3]NAC has recognized medicine uses. A US National Library of Medicine drug page says inhaled acetylcysteine is used along with other treatments to relieve chest congestion from thick mucus, and that it is sometimes used for acetaminophen overdose. [1] One trial describes NAC as a commonly used dietary supplement. [4] Its regulatory status in different countries is not described in the sources we read.
Both are often described as "antioxidants". That label comes from test-tube chemistry; whether a supplement changes how someone feels or their disease risk is a separate question.
Evidence labels used here: biomarker only (a blood marker changed), insufficient evidence, marketing claim, and "Proper evidence not found" where we searched and found nothing usable.
Side by side
| Question | NAC | Glutathione taken by mouth |
|---|---|---|
| What is the medicine or established use? | Inhaled form for mucus; sometimes used by clinicians for acetaminophen overdose. [1] | None described in the sources we read |
| Does a supplement raise glutathione? | In a 2-week trial in 114 healthy older adults, glycine plus NAC (2.4, 4.8 or 7.2 g a day, a study amount) did not raise total glutathione, the primary endpoint; a later subgroup analysis suggested a rise in people with high oxidative stress and low starting glutathione. [3] Biomarker only. | In a 6-month placebo-controlled trial of 54 non-smoking adults, 250 or 1,000 mg a day raised glutathione in blood, red cells and other cells, and levels returned to baseline after a 1-month washout. [5] Biomarker only. |
| Head to head | A 3-week crossover trial in 20 people with metabolic syndrome compared NAC, ordinary oral glutathione and a new under-the-tongue glutathione form; the under-the-tongue form raised glutathione more than the other two. [4] Two authors list a commercial laboratory as their affiliation; the abstract does not give a separate NAC-versus-oral-glutathione result. | Same trial. [4] |
| Health outcomes for the "boost glutathione" claim | Proper evidence not found | Proper evidence not found |
Both trials measured glutathione-related markers, not symptoms or disease. The authors of the glycine-and-NAC trial are Nestlé employees, and the disclosure says Nestlé Health Sciences markets products using those ingredients. [3] A cell-level change in a blood marker does not show that a person will feel or function better, and the 2015 authors of the crossover trial themselves call glutathione's low bioavailability a limit on the interest of supplementing. [4]
What we searched: PubMed (2026-10-23) for N-acetylcysteine and glutathione levels in randomized human trials, and for NAC safety reviews. We did not find a trial testing NAC against oral glutathione on a health outcome.
Frequently asked questions
Is NAC the same as glutathione?
No. Glutathione is the body's own molecule; NAC is a different compound used as a medicine and as a supplement, tested partly because cysteine is needed to make glutathione. [2][1]
Which raises glutathione more, NAC or a glutathione supplement?
Different trials, populations and forms give different answers. A 6-month trial found oral glutathione raised blood levels, while a glycine-plus-NAC trial did not raise total glutathione in healthy older adults. [5][3]
Does a higher glutathione level mean better health?
Not shown. These are biomarker results, and for health outcomes in a head-to-head comparison: Proper evidence not found. [4]
Can NAC treat an acetaminophen overdose at home?
No. Call Poison Help at 1-800-222-1222 or 911. Clinicians sometimes use acetylcysteine for overdose. [1]
Are there safety concerns?
NAC at higher amounts in lung-disease trials caused stomach symptoms about as often as control groups, but those people are not the general public, so ask a clinician or pharmacist first. [6]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and who should ask first
- NAC side effects. A review of 41 articles on NAC at 600 to 3,000 mg a day in chronic lung conditions found stomach symptoms were reported, but no more often than in control groups; the review notes a maximum licensed dose in chronic use of 600 mg a day and was sponsored by a drug company. [6] Those findings come from people with lung disease, mostly using the oral form.
- Asthma and inhaled use. The drug page for inhaled acetylcysteine asks people to tell their doctor about asthma. [1]
- Pregnancy and breastfeeding. The same drug page asks people to tell their doctor if they are pregnant, plan to be, or are breastfeeding. [1] It describes the inhaled medicine, not supplements. Safety of supplement forms is not described in the sources we read. Ask a clinician: pregnancy and breastfeeding.
- Medicines. The drug page asks you to tell your doctor and pharmacist about all vitamins and supplements you take. [1] See medication interactions.
- Children, kidney and liver conditions, and surgery. Not described in the sources we read for either supplement; ask a clinician, and tell the surgical team about supplements: supplements before surgery.
- Injections and IV drips. Glutathione given by injection or drip is a different question: see what regulators say.
- Official intake levels. None of the sources we read gives an official recommended intake or upper limit for NAC or glutathione, so none is stated.
- Quality. Product contents vary; see quality testing.
More detail: N-acetylcysteine, where precursors are covered, glutathione forms and GlyNAC in aging research.
References
- Acetylcysteine Oral Inhalation. MedlinePlus Drug Information, National Library of Medicine (US), last revised 15 March 2017. Read 2026-10-23.
- Lu SC. Glutathione synthesis. Biochim Biophys Acta 2013 (PubMed abstract). Read 2026-10-23.
- Lizzo G, Migliavacca E, Lamers D, et al. A randomized controlled clinical trial in healthy older adults to determine efficacy of glycine and N-acetylcysteine supplementation on glutathione redox status and oxidative damage. Front Aging 2022 (PubMed abstract). Read 2026-10-23.
- Schmitt B, Vicenzi M, Garrel C, Denis FM. Effects of N-acetylcysteine, oral glutathione (GSH) and a novel sublingual form of GSH on oxidative stress markers: a comparative crossover study. Redox Biol 2015 (PubMed abstract). Read 2026-10-23.
- Richie JP Jr, Nichenametla S, Neidig W, et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Eur J Nutr 2015 (PubMed abstract). Read 2026-10-23.
- Calverley P, Rogliani P, Papi A. Safety of N-acetylcysteine at high doses in chronic respiratory diseases: a review. Drug Saf 2021 (PubMed abstract). Read 2026-10-23.