Supplement evidence

043 / 575Amino-acid derivative

N-acetylcysteine (NAC)

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The short answer

A regulated medicine for acetaminophen poisoning and selected pulmonary indications; supplement claims are separate.

Evidence and scope: Conditional or population-specific
This status does not grade the ingredient for every goal, outcome, or person.
Important limitation: General antioxidant, anti-aging, and lifespan claims are not established.
Before deciding: Can cause GI symptoms and interact with nitroglycerin and other medicines.

01 / PRACTICAL GUIDE

Dose, absorption, and combinations

These are indication-specific reference or studied ranges—not a personalized prescription. Start with the objective, then check the form, label, medicines, and health conditions.

Reference range by objective

Respiratory research600–1,200 mg/day oral NAC in many chronic-respiratory trials

Reference or studied range—not a personalized prescription. The product label or a clinician may specify a different dose.

Dose source ↗

More is not automatically better. A clinician or product label may specify a different amount.

Absorption / solubilityWater-soluble

Water-soluble or readily water-dispersible. This does not mean excess is always harmless.

How it is commonly taken

Take with or without food; food may reduce nausea.

Do not combine casually

Nitroglycerin, anticoagulants, asthma, surgery, and prescription acetaminophen treatment require medical oversight.

Dose and use source ↗

Dose and use links lead to primary or official source material. Search links are discovery tools, not proof that every returned paper applies.

02 / EVIDENCE

What the research says

We keep supportive, mixed, negative, safety, and contextual findings together. The headline never replaces the underlying papers.

4research papers in this ledger

29unique primary studies represented

3,586unique participants represented

These are audited counts for this JIVANA collection, not search-result totals. Participants are counted once when multiple papers use the same cohort; review papers are not added again to participant totals.

Open the research timelineResearch timeline

Entries are ordered by publication year. A study period appears only when the source reports it.

2024

Mixed or qualifiedPMID 39504621

Efficacy of N-acetylcysteine for patients with depression

Depression scores showed a small pooled improvement, particularly in bipolar disorder, but the confidence interval was broad and the authors called for larger trials. This is adjunctive, diagnosis-specific evidence.

Published: 2024Duration: 8–24 weeksn=904 participants12 primary studies represented

Study design and methods

Design: Updated systematic review and meta-analysis of 12 randomized trials
Population: 904 patients with depressive symptoms in psychiatric disorders
Intervention: Adjunctive NAC 1,000–3,000 mg/day versus placebo
Outcome: Change in depression scores

Funding or conflict note: The authors declared no conflicts of interest.

Open research record ↗

2023

Does not support the tested claimPMID 36927162

The efficacy of N-acetylcysteine in chronic obstructive pulmonary disease patients

NAC did not significantly reduce exacerbations, preserve lung volume, improve respiratory quality of life, or change adverse-event rates in the pooled evidence.

Published: 2023n=2,137 participants9 primary studies represented

Study design and methods

Design: Meta-analysis of nine randomized placebo-controlled trials
Population: 2,137 adults with COPD
Intervention: Long-term oral NAC versus placebo
Outcome: Exacerbations, lung volumes, respiratory quality of life, glutathione, and adverse events

Open research record ↗

2023

Does not support the tested claimPMID 37071164

N-acetylcysteine for preventing post-intravenous contrast acute kidney injury

Low-certainty evidence found no significant reduction in acute kidney injury; mortality and hospital-stay estimates were also very uncertain. Routine prophylactic benefit was not established.

Published: 2023n=545 participants8 primary studies represented

Study design and methods

Design: Systematic review and meta-analysis of eight randomized trials
Population: 545 patients with kidney impairment receiving intravenous contrast for non-interventional imaging
Intervention: NAC versus no NAC
Outcome: Post-contrast acute kidney injury, dialysis, mortality, serious adverse events, and hospital stay

Open research record ↗

2023

Does not support the tested claimPMID 37712506

Efficacy and acceptability of adjunctive N-acetylcysteine for psychotic disorders

NAC did not improve total, positive, negative, or general psychopathology scores at either follow-up window, and dropout did not differ. Routine augmentation was not supported.

Published: 2023n=594 participants8 primary studies represented

Study design and methods

Design: Systematic review and meta-analysis of eight randomized trials
Population: 594 patients with psychotic disorders receiving antipsychotic medication
Intervention: Adjunctive NAC versus placebo
Outcome: PANSS symptoms and dropout

Funding or conflict note: Psychiatric trial overlap with the depression synthesis is possible, so this review is excluded from aggregate totals.

Open research record ↗

Unscreened discovery appendix—not evidence2,044 candidate publicationsSearch run: Aug 21, 2026

Complete for the displayed PubMed query at the search timestamp—not for all databases or every possible synonym. Candidates can be irrelevant, duplicate the same study, or report negative findings. They are never summed as evidence or participants until screened.

03 / SOURCES

Start with the source material

Official evidence overviewNIH Office of Dietary Supplements directory Live PubMed discovery searchNational Library of Medicine

The live search is for discovery only. Search-result counts change and are not included in the audited totals above.

Recent PubMed discovery recordsDirect links to the first 12 records returned by the reproducible search. These are discovery candidates—not reviewed summaries or a count of supportive findings.

04 / EXPERT CONTEXT

Expert context—not evidence

Expert positions are dated context—not scientific evidence. They never raise the evidence status or become consensus by repetition.

No direct, source-verified endorsement is currently recorded. Research authorship or discussion alone is not treated as endorsement.