NAC

Tier-CPublic-ready7/2/2026

Blood-Level or Deficiency Marker is closer to a research marker, so it should be read separately from a directly felt benefit.

Some human supplement-context evidence is present and directly informs the score.

Representative tier calculated from paper evidence that passed the collection audit.

Papers analyzed

109

Caution signal

Low

Representative score

45.2

Blood-Level or Deficiency MarkerFatigue and energyGlucose and metabolic health markers

Main benefit evidence

The representative ingredient tier is calculated from these target-level evidence groups.

Nutrient status and deficiency

1 studiesTier-C

Blood-Level or Deficiency Marker

Some positive signal observedResearch marker focusPatient-group study

This is based on lab markers such as blood levels, deficiency correction, or absorption. Read it separately from directly felt outcomes.

Evidence score

44.0

Study context

Patient-group study

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Fatigue and energy

1 studiesTier-C

Fatigue and energy

Some positive signal observedFelt benefit focusSupplement context

Potential benefit studied in Fatigue and energy.

Evidence score

39.3

Study context

Supplement context

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Glucose and metabolic health

2 studiesTier-C

Glucose and metabolic health markers

Some positive signal observedResearch marker focusPatient-group study

This card is closer to a measured biomarker or lab outcome than a directly felt user benefit. These findings come from a defined study population, so everyday effects may differ.

Evidence score

35.2

Study context

Patient-group study

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Stress and mood

2 studiesTier-C

Stress Response and Sleep Changes

Some positive signal observedFelt benefit focusPatient-group study

These findings come from stress response, cortisol, anxiety, or sleep outcomes. They may mix felt benefits with physiological markers.

Evidence score

32.5

Study context

Patient-group study

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Recent research

Updated This Month10 new papers

Observed range in repeated studies

This range includes studies in specific patient groups. It is not a general dose or recommendation.

Lower observed study value

600

mg/day

8 independent studies

Higher observed study value

3600

mg/day

Only ranges repeated in human, oral, single-ingredient studies are shown.

Not personal dosing instructions, recommendations, or safety limits.

Side effects and combination findings in studies

Findings from studies of this ingredient alone are separated from findings involving another supplement or medication.

Caution index

0.8

Caution band: Low

Caution signals

Side effects + combos + curated rules

Key precautions

No curated contraindication rule is available yet, but literature caution signals are shown below.

1 combo signals and 0 added-signal combos shown below.

These are signals reported in studies. They do not predict what will happen to an individual.

Findings to review with care

Side effects reported for the ingredient alone are separated from findings involving another supplement or medication.

Side effects reported when this ingredient was used alone

Symptoms or adverse events reported in studies of this ingredient without another active ingredient.

Adverse Events from NAC1 papers

The most frequent adverse events reported with NAC were anaphylactic reactions, cutaneous reactions for IV route, and intestinal reactions for oral route.Human studies · Systematic review

Adverse effect signal1 papers

The most frequent adverse events reported with NAC use were anaphylactic reactions, followed by cutaneous adverse events for the intravenous route and intestinal adverse events for the oral route.Human studies · Study type not identified

Potential side effects1 papers

The review discusses potential side effects of NAC and its formulations for drug delivery without specifying severity or frequency.Human studies · Systematic review

Minor adverse events1 papers

The meta-analysis reports that N-acetylcysteine is associated with minor adverse events, though the overall tolerability is described as good.Human studies · Meta-analysis

Gastrointestinal symptoms1 papers

Gastrointestinal symptoms were significantly greater in the NAC group compared to the placebo group in a 16-week RCT.Human studies · Randomized controlled trial

Gastrointestinal adverse events1 papers

Nine drug-related gastrointestinal adverse events occurred, which resolved spontaneously or with dose reduction, indicating a mild safety signal.Human studies · Randomized controlled trial

Adverse events and tolerability1 papers

Three participants discontinued the trial due to adverse effects, though the overall frequency of adverse events was low and not statistically different between groups.Human studies · Randomized controlled trial

Adverse events (abdominal discomfort, muscle pains, insomnia, headache, etc.)1 papers

NAC was generally well tolerated with 63% of participants reporting mild to moderate adverse events such as abdominal discomfort, muscle pains, and insomnia, none leading to discontinuation.Human studies · Randomized controlled trial

Positive combinations studied

Positive combination findings are separated by how the study compared the groups. This is not a recommendation to combine them.

Positive findings when used together

The combination had a positive result, but the contribution of each ingredient could not be separated.

GlycineIn a randomized clinical trial of older adults, GlyNAC (a combination of glycine and NAC) supplementation for 16 weeks improved glutathione deficiency, oxidative stress, and mitochondrial dysfunction compared to placebo.

Evidence summaries

Paper IDs and full lists are private. Only study types and summaries are shown.

Key Evidence #1

Public scholarly dataCitation signal: 1376

observational

Increased risks of death and hospitalization were observed in patients with idiopathic pulmonary fibrosis who were treated with a combination of prednisone, azathioprine, and NAC, as compared with placebo, providing evidence against the use of this combination

Key Evidence #2

Public scholarly dataCitation signal: 441

review

The purpose of this chapter is to provide an overview of the medicinal effects and applications of NAC to human health based on current therapeutic evidence.

Key Evidence #3

Public scholarly dataCitation signal: 404

observational

It is shown that cocaine self-administration induces metaplasticity that inhibits further induction of synaptic plasticity, and this impairment can be reversed by NAC, a drug that also prevents relapse.

3 more summariesLimited representative sample by study type.

Public scholarly dataCitation signal: 380

review

The validity of conventional assumptions and the scope of a newly discovered mechanism of action, namely the conversion of NAC into hydrogen sulfide and sulfane sulfur species, are discussed.

Public scholarly dataCitation signal: 347

observational

Data suggest that VNI2 regulates xylem cell specification as a transcriptional repressor that interacts with VND proteins and possibly also with other NAC domain proteins.

Public scholarly dataCitation signal: 281

observational

An overview of the most relevant and recent evidence on the clinical application of NAC is provided, with a focus on respiratory diseases, acetaminophen poisoning, disorders of the central nervous system, cardiovascular disease, contrast-induced nephropathy, a

NAC

Evidence score: 45.2|Caution index: 0.8

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