Cysteine donor for glutathione synthesis; drug-strength efficacy for specific uses.
Solid, cheap, well-studied. FDA occasionally hassles supplement sellers about NAC being a 'drug', but availability continues.
NAC (N-Acetylcysteine) is a glutathione precursor with evidence grade B, meaning it is supported by human RCTs. We track 7 products containing NAC. Typical doses range from 10 to 900 mg per serving. The top-ranked product scores 7.0 out of 10 on our composite scale (dose, evidence, price, testing, transparency). Prices range up to $109.95 per month.
| Product | Brand | Dose | Price/mo | 3rd-party tested | Score |
|---|---|---|---|---|---|
| N-Acetyl L-Cysteine (NAC) Powder | BulkSupplements | 600 mg | $20.97 | No | 7.0 |
| Jarrow Formulas N-A-C Sustain, 600 mg | Jarrow Formulas | 600 mg | $25.99 | No | 6.9 |
| NAC (N-Acetyl-L-Cysteine) 900 mg | Pure Encapsulations | 900 mg | $101.00 | No | 6.7 |
| NAC - N-Acetylcysteine (Cysteplus) | Thorne HealthTech | 500 mg | $29.00 | Yes | 6.6 |
| Longevity | Momentous | 600 mg | $109.95 | Yes | 6.2 |
Scores are editorial judgments, not a scientific standard. See how we score.
A form of cysteine (an amino acid) that your body converts into glutathione, your master antioxidant. Used medically for paracetamol overdose and lung mucus clearance.
Restores glutathione reliably. Real benefits in COPD, chronic bronchitis, and glutathione depletion in older adults (especially with glycine). Longevity benefits inferred from oxidative-stress mechanism, not directly tested.
Solid, cheap, well-studied. FDA occasionally hassles supplement sellers about NAC being a 'drug', but availability continues.
N-acetyl-L-cysteine. Deacetylated to cysteine, condensed with glutamate and glycine to form GSH.
Multiple trials show restoration of hepatic and RBC glutathione. Kumar 2021 (GlyNAC) demonstrated broad aging biomarker improvements at 800 mg NAC + 3.6 g glycine per day.
~6 hours.
Smells like sulfur (rotten eggs). Enteric-coated forms reduce this. Don't combine with nitrates without medical supervision.
The trial dose above is our editorial pick from the published human trials for this ingredient. We choose the dose that the best-available studies used on the endpoint most relevant to longevity. The range shows the lowest and highest doses tested in published trials. The landmark studies below are the papers we read to set it. You can click through and check our work.
When new trials publish, our automated sweeps flag them. If a new study materially changes the dose, we update it through editorial review and record the old dose, new dose, and the triggering study in every affected product's recommendation history. The dose is never changed automatically.
Regulatory events, evidence grade changes, and key research milestones for NAC, most recent first. Studies link to the paper; regulatory entries name and link the responsible authority.
Verified 2026-07-14. We update this section as new peer-reviewed trials land.
NAC's clearest psychiatric evidence is as an add-on treatment for depression symptoms, not a standalone cure. Zhang et al.'s 2024 meta-analysis of 12 RCTs and 904 depressed patients found adjunctive NAC at 1,000-3,000 mg/day for 8-24 weeks significantly improved depression scores versus placebo (SMD -0.24, 95% CI -0.44 to -0.05, P=.02) (https://pubmed.ncbi.nlm.nih.gov/39504621/). NAC is also an established, FDA-approved antidote for acetaminophen overdose and has decades of safety data in that clinical use, giving it a strong pharmacological safety track record outside the psychiatric context.
NAC is marketed as a broad mental-health and mood supplement effective across depression, bipolar disorder, and general anxiety, but a 2018 meta-analysis of 6 RCTs and 701 patients found adjunctive NAC was efficacious for schizophrenia (SMD -0.74) yet showed no significant effect on depressive or manic symptoms in bipolar disorder and only a small effect on major depressive disorder alone (https://onlinelibrary.wiley.com/doi/abs/10.1111/acps.12862). Marketing for NAC as a hangover cure or general liver detox supplement also outruns current evidence: while a 28-day pilot trial found NAC feasible and safe for alcohol use disorder with some improvement in consumption measures, the larger confirmatory multi-site trial was still recruiting as of its 2025 protocol publication, so definitive efficacy for alcohol-related outcomes is not yet established (https://pmc.ncbi.nlm.nih.gov/articles/PMC12421191/).
1,000-3,000 mg/day for psychiatric adjunctive use, split into two doses; 2,400 mg/day used in alcohol use disorder trials
NAC has shown a safety profile similar to placebo across psychiatric RCTs, with the 2018 major mental disorders meta-analysis reporting adverse drug reactions and discontinuation rates comparable between NAC and control groups (https://onlinelibrary.wiley.com/doi/abs/10.1111/acps.12862). Mild gastrointestinal upset, including nausea and reflux, is the most commonly reported side effect. NAC is well established as safe at high intravenous doses for acetaminophen overdose treatment under medical supervision. People with asthma should use oral NAC cautiously since inhaled forms have triggered bronchospasm in some individuals, though this is a different route of administration than oral supplements.
Meta-analysis of 12 RCTs found adjunctive NAC significantly improved depression scores versus placebo, with a modest effect size, particularly in bipolar disorder.
Read study →A multi-site RCT protocol describes testing 2,400 mg/day NAC for 12 weeks in alcohol use disorder, following an earlier 28-day pilot that found NAC feasible, safe, and associated with some improvement in drinking measures.
Read study →A fully powered 8-week RCT in youth aged 15-25 found NAC 2,400 mg/day showed no overall benefit over placebo for alcohol use disorder, but significantly reduced drinking in the subgroup with moderate to severe disorder.
Read study →GlyNAC for 24 weeks improved glutathione, inflammation, insulin resistance.
Read study →All products in our catalog that contain NAC, ranked by our overall score. Ranking is editorial, never paid.
BulkSupplementsStatus as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.
Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.
Jarrow FormulasStatus as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.
Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.
Pure EncapsulationsStatus as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.
Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.
Thorne HealthTechStatus as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.
Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.
MomentousMulti-ingredient bundle
Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.
Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.
DoNotAgeStatus as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.
Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.
ProHealth LongevityStatus as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.
Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.
Molecules in the same class, plus the actives most often formulated alongside NAC in our catalogue.
See NAC in context: the mechanism it acts through, the biomarker it moves, the products that dose it, and the trials that tested it.
View NAC on the Longevity Map →A form of cysteine (an amino acid) that your body converts into glutathione, your master antioxidant. Used medically for paracetamol overdose and lung mucus clearance.
The trial dose in published human studies is 600 mg per day, with a range of 600 to 1800 mg per day. Always consult a qualified clinician before starting any supplement.
Smells like sulfur (rotten eggs). Enteric-coated forms reduce this. Don't combine with nitrates without medical supervision.
We track 7 products containing NAC. The top-ranked product scores 7.0 out of 10 on our composite scale, which evaluates dose, evidence, price, third-party testing, and transparency. See the comparison table above. Scores are editorial judgments, not a scientific standard.
NAC has evidence grade B, meaning it is supported by human RCTs. Grade A means replicated human RCTs with hard endpoints. Grade B means human RCTs with biomarker outcomes. Grade C means mixed or small human trials. See our evidence grading methodology.
Evidence grades are reviewed when new human RCTs are published. Product counts update automatically as new products are added. Dose ranges reflect published trial data, not brand recommendations. Read how we verify.