NAC dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
A glutathione precursor that is FDA-approved as a mucolytic and antidote for acetaminophen overdose, and studied more broadly in psychiatry and respiratory health.
- People given it
- 0
- Human studies
- 0
- Found nothing
- 0
Dose
No human dose established
No published study on this page has given this compound to people and reported a result.
3 human studies where nobody was given it
No first-hand reports gathered yet. That is a gap in what we have collected, not a finding that nothing has been reported.
What it has been measured to do
Nothing indexed yet
The 4 citations on this page do not report a result for any of the 36 goals indexed here. Registry entries, pharmacokinetics, safety reporting and regulatory records are not outcome evidence, and most of what sits here is one of those.
When this earns a spot
The owner's trigger is stressed liver enzymes. The on-label human evidence is paracetamol overdose and mucus. Those uses do not automatically transfer to a longevity capsule. Asthma (as a nebulized drug) and a long bottle list are clinician context.
Owner stack tier 2
Bloodwork that belongs beside the bottle
Bring every bottle, including tea extracts, to the draw.
Default retest window: 90 days. If the named marker did not move, stop.
- AST also comes from muscle.
- A new 'detox' stack plus NAC is two variables.
Reading the number
Repeatedly high ALT or AST is a clinician week, not a shopping week. If enzymes were the reason and they did not move, stop the NAC.
Marker glossary: Liver enzymes.
What people typically order
Ask for ALT, AST, and GGT. The Archive does not order liver panels.
Show full evidence
Overview
N-acetylcysteine is a well-absorbed precursor of cysteine that supports glutathione synthesis. It is FDA-approved as a mucolytic and, intravenously, as the standard antidote for acetaminophen (paracetamol) overdose, where the evidence is strong. It has also been studied in psychiatry, addiction, and respiratory conditions, with more variable results.
Mechanism of action
Provides cysteine to replenish glutathione, directly scavenges free radicals, and modulates glutamatergic signaling in the brain.
The evidence, charted
Fig. 1a · evidence scale
2,555people, across 2 human studies cited here
- 1988 · New England Journal of Medicine2,54099%
- 1977 · The Lancet151%
One study holds 99% of these participants, so the total is less independent than its size suggests. Counts are the enrollment each human citation on this page states, which includes observational cohorts where nobody was given the compound. 1 further human citation states no participant count and is not counted here. Studies still recruiting are excluded, and only studies cited on this page are counted.
Fig. 1b · evidence mix
3 of 4 citations here are human work, the rest is not.
- Human · given to people375%
- Review · summarises other work125%
Counted from the citation list on this page, typed as this page types it. It understates any literature larger than the sources we cite, and a review counts once however many studies it covers.
Fig. 2 · evidence over time
Evidence spans 4 distinct years, 1977 to 2025, counted from the citation list on this page.
Fig. 3 · legal status at a glance
US
Approved
UK
Approved
AU
Approved
CA
Approved
Approved in all four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 5 · molecular identity
- Modality
- Supplement
- Molecular weight
- 163.2 Da
- Half-life
- About 5.5 hours
- Sequence length
- None on file
Short, 1 to 6 hours
No amino acid sequence is on file for NAC, which is expected: a supplement is not built from residues.
Key studies & citations
- Human1988Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose: analysis of the national multicenter study (1976 to 1985)
NAC works, and this is the study that made it standard care for paracetamol poisoning. Doctors pooled records from 2,540 people treated across the country after an overdose. Among those given NAC by mouth within ten hours, serious liver damage happened in about one in sixteen. Starting within eight hours protected people whatever their blood drug level was. Nobody here was picked by chance to go without NAC, because withholding it would have been unsafe.
In 2,540 treated overdose patients, hepatotoxicity fell to 6.1% when NAC was started within 10 hours; NAC was protective regardless of initial acetaminophen level when given within 8 hours.
- Human1977Treatment of paracetamol (acetaminophen) poisoning with N-acetylcysteine
This is the first time anyone gave NAC into a vein for paracetamol poisoning, and it worked. Fifteen poisoned patients were treated. Of the twelve who got it within ten hours, eleven kept normal or near normal liver tests. The drip schedule still used today comes from this report. Everyone here was treated, so there was no untreated group to compare against. It is a first look rather than a trial, and the large studies that followed are what settled the question.
First report of intravenous NAC in 15 poisoned patients: liver function stayed normal or near normal in 11 of 12 treated within 10 hours; established the IV regimen.
- Human2025Acetadote (acetylcysteine) injection: prescribing information
This is the regulator's own instruction sheet, not a study. It approves NAC given into a vein for people who have swallowed a dangerous amount of paracetamol. The drip should start within eight to ten hours of the overdose to prevent or limit liver damage. The label's main warning is a reaction that looks like a severe allergy, with flushing, rash, wheeze or a drop in blood pressure. It carries no evidence of benefit for anything else, because it was never written to.
FDA-approved label: IV acetylcysteine given within 8 to 10 hours of a potentially hepatotoxic acetaminophen ingestion to prevent or lessen liver injury; anaphylactoid reactions are the key warning.
- Review2015Clinical trials of N-acetylcysteine in psychiatry and neurology: a systematic review
Favorable but early evidence in several psychiatric and neurological conditions; larger controlled trials still needed and results vary by indication.
Frequently asked questions
Has NAC been tested in people?
A glutathione precursor that is FDA-approved as a mucolytic and antidote for acetaminophen overdose, and studied more broadly in psychiatry and respiratory health. 3 human studies where nobody was given it. 0 people given it across 0 completed trials. 0 found nothing.
What is the NAC dosage?
No human dose established. No published study on this page has given this compound to people and reported a result. 3 human studies where nobody was given it
Is NAC FDA-approved?
FDA-approved (mucolytic; acetaminophen overdose antidote); also sold as a supplement
Is NAC the same as glutathione?
No. NAC is a precursor the body uses to make glutathione, and it is much better absorbed orally than glutathione itself.