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N-Acetyl Cysteine (NAC)

antioxidant support, mucolytic agent, acetaminophen overdose antidote

supplement
Evidence · Grade D
Meta-analysis availableHuman trial evidenceTraditional useInteraction riskNeeds more research

Glutathione precursor with mucolytic and detox effects.

N-Acetyl Cysteine (NAC) is a derivative of the amino acid L-cysteine. It is a precursor to glutathione, a powerful antioxidant in the body. NAC is recognized for its mucolytic properties, meaning it can help thin mucus. It is also used in conventional medicine as an antidote for acetaminophen overdose. While often available as a dietary supplement, its use in various health conditions is an area of ongoing research. Due to its role in glutathione production, NAC is often explored for conditions related to oxidative stress and inflammation.

Quick answer

What it is: N-Acetyl Cysteine (NAC) is a derivative of the amino acid L-cysteine.

May support:Multiple Sclerosis (MS), Lupus (SLE), Viral Infections, Common Cold/Flu, Chronic Bronchitis, Bipolar Disorder, OCD, Allergic Rhinitis, Sjögren's Syndrome, Endometriosis, Parkinson's Disease, Leaky Gut Syndrome, Urticaria, Psoriasis, Lyme Disease, Autoimmune Thyroid Disease, Chronic Sinusitis, Melasma, Multiple Sclerosis, Asthma, Rheumatoid Arthritis, Beauty & Anti-Aging, Autism Spectrum, PTSD, Non-Alcoholic Fatty Liver Disease (NAFLD), Liver Disease, Vitiligo, Brain Fog, Sinus Infections, Atherosclerosis, Thyroid Disorders, Cancer (Adjunctive Support), PCOS, COPD, Chronic Fatigue Syndrome, Depression, Mold Illness / CIRS, SIBO

Evidence:Evidence · Grade D

Evidence Summary

Evidence · Grade D

Without specific PubMed studies provided, the evidence grade for NAC's efficacy in various conditions cannot be definitively established. General knowledge suggests that while NAC is well-studied for acetaminophen overdose (a medical treatment), its efficacy as a dietary supplement for other conditions often relies on a mix of in vitro studies, animal models, and human clinical trials with varying methodologies and outcomes. A lack of specific, high-quality human trials for particular ailments would lead to a cautious assessment.

Last reviewed · Jun 2026

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Why It Works

Provides cysteine for GSH synthesis; modulates glutamate.

How it works in more detail

N-Acetyl Cysteine (NAC) is deacetylated to cysteine, which is then used in the synthesis of glutathione (GSH). GSH is a tripeptide (glutamate-cysteine-glycine) and a major endogenous antioxidant that protects cells from oxidative damage by neutralizing reactive oxygen species. NAC also exhibits direct antioxidant activity by scavenging hydroxyl radicals and hypochlorous acid. Furthermore, NAC's mucolytic action is attributed to its free sulfhydryl group, which can break disulfide bonds in mucoproteins, thereby reducing the viscosity of mucus secretions in the respiratory tract.

How to use

Always consult a qualified clinician.

Editorial guidance

Suggested dosage
600–1800 mg/day
Research dosage range
Research dosages for NAC vary widely depending on the condition being studied, ranging from 600 mg/day for antioxidant support to much higher doses (e.g., 10-30 g intravenously) for acetaminophen overdose.
Typical onset
Mucolytic effects may be observed within hours to days. Antioxidant benefits, particularly those related to glutathione replenishment, may take longer to manifest, often weeks to months of consistent
Typical forms
Capsule, Tablet, Powder, Effervescent tablet, Intravenous solution (medical use), Inhalation solution (medical use)
Quality markers
Look for NAC supplements from reputable manufacturers that provide third-party testing for purity and potency. Ensure the product is free from unnecessary fillers, artificial colors, and common allergens. Consider products with good manufacturing practices (GMP) certification.
Medication interactions
  • Nitroglycerin and other nitrates (may enhance effects)
  • Activated charcoal (may reduce NAC absorption)
  • Immunosuppressants (potential interaction)
  • Anticoagulants/antiplatelets (theoretical increased bleeding risk at high doses)
Avoid if
  • Known hypersensitivity to NAC
  • Active peptic ulcer (use with caution)
  • Asthma (use with caution, especially inhaled forms)

Community tips

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Suggested dosage

600–1800 mg/day

General guidance — discuss specifics with a clinician.

Active medicinal compounds

N-Acetyl Cysteine

Traditional use

While NAC itself is a synthetic derivative of cysteine, the concept of supporting detoxification and respiratory health through dietary means has roots in traditional medicine systems. However, NAC as a specific compound does not have a traditional use history.

Safety

Safety warnings

Avoid with nitroglycerin; sulfur odor common.

Avoid if

  • Known hypersensitivity to NAC
  • Active peptic ulcer (use with caution)
  • Asthma (use with caution, especially inhaled forms)

Medication interactions

  • Nitroglycerin and other nitrates (may enhance effects)
  • Activated charcoal (may reduce NAC absorption)
  • Immunosuppressants (potential interaction)
  • Anticoagulants/antiplatelets (theoretical increased bleeding risk at high doses)

Reported side effects

  • Nausea
  • Vomiting
  • Diarrhea
  • Stomach upset
  • Heartburn
  • Rash
  • Bronchospasm (rare, especially in asthmatics)

General guidance — discuss specifics with a clinician.

Evidence ecosystem

Scientific literature, clinical guidance, government sources, ongoing research, traditional use, and lived experience — grouped by source type and quality.

Overall grade (D)

Without specific PubMed studies provided, the evidence grade for NAC's efficacy in various conditions cannot be definitively established. General knowledge suggests that while NAC is well-studied for acetaminophen overdose (a medical treatment), its efficacy as a dietary supplement for other conditions often relies on a mix of in vitro studies, animal models, and human clinical trials with varying methodologies and outcomes. A lack of specific, high-quality human trials for particular ailments would lead to a cautious assessment.

Filter by source type

Meta-Analyses(1)

Pooled analyses across multiple human trials.

Very High Quality

  • Efficacy of N-Acetylcysteine in Polycystic Ovary Syndrome: Systematic Review and Meta-Analysis.

    Viña I, Viña JR, Carranza M, Mariscal G · Nutrients · 2025 · n=2515

    Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects women of reproductive age and requires better treatment. N-acetylcysteine (NAC) is known to be beneficial under such conditions owing to its antioxidant potential and insulin-sensitizing properties. The effect of NAC on the reproductive outcomes of PCOS patients was examined in this meta-analysis. In accordance with PRISMA standards, this meta-analysis included studies that compared N-acetylcysteine, metformin, clomiphene citrate, and a placebo in patients with POCS. The main indicators were follicular growth, endometrial thickness, and hormone level. The risk of bias was evaluated using the Cochrane ROB2 tool. Twenty-two studies (n = 2515) were included. NAC was associated with a statistically significant increase in progesterone (SMD 0.95, 95% CI: 0.13-1.77, p = 0.02) and endometrial thickness (SMD 0.58, 95% CI: 0.10-1.06, p = 0.02) compared to the placebo and other drugs (SMD 0.71, 95% CI: 0.48-0.94, p &l

    Meta-AnalysisPubMedVery High Quality

Observational Studies(2)

Cohort, case-control, and cross-sectional human studies.

Moderate Quality

  • Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce.

    Sarris J, Ravindran A, Yatham LN, Marx W, Rucklidge JJ, McIntyre RS · The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry · 2022

    The therapeutic use of nutrient-based 'nutraceuticals' and plant-based 'phytoceuticals' for the treatment of mental disorders is common; however, despite recent research progress, there have not been any updated global clinical guidelines since 2015. To address this, the World Federation of Societies of Biological Psychiatry (WFSBP) and the Canadian Network for Mood and Anxiety Disorders (CANMAT) convened an international taskforce involving 31 leading academics and clinicians from 15 countries, between 2019 and 2021. These guidelines are aimed at providing a definitive evidence-informed approach to assist clinicians in making decisions around the use of such agents for major psychiatric disorders. We also provide detail on safety and tolerability, and clinical advice regarding prescription (e.g. indications, dosage), in addition to consideration for use in specialised populations. The methodology was based on the WFSBP guidelines development process. Evidence was assessed based on th

    Observational StudyPubMedLow Quality

  • Nutritional psychiatry: the present state of the evidence.

    Marx W, Moseley G, Berk M, Jacka F · The Proceedings of the Nutrition Society · 2017

    Mental illness, including depression, anxiety and bipolar disorder, accounts for a significant proportion of global disability and poses a substantial social, economic and heath burden. Treatment is presently dominated by pharmacotherapy, such as antidepressants, and psychotherapy, such as cognitive behavioural therapy; however, such treatments avert less than half of the disease burden, suggesting that additional strategies are needed to prevent and treat mental disorders. There are now consistent mechanistic, observational and interventional data to suggest diet quality may be a modifiable risk factor for mental illness. This review provides an overview of the nutritional psychiatry field. It includes a discussion of the neurobiological mechanisms likely modulated by diet, the use of dietary and nutraceutical interventions in mental disorders, and recommendations for further research. Potential biological pathways related to mental disorders include inflammation, oxidative stress, th

    Observational StudyPubMedLow Quality

Clinical Trial Registries(8)

Registered ongoing or completed trials (ClinicalTrials.gov).

Moderate Quality

  • Physiological Effects of N-Acetyl Cysteine in Patients With Multiple Sclerosis

    n=55 · NCT03032601 · ENROLLING_BY_INVITATION · ENROLLING_BY_INVITATION

    Multiple Sclerosis (MS) is a disease in which the myelin surrounding the nerve cells is damaged which affects functioning. MS usually is treated with medications designed to reduce the occurrence of future MS events. Evidence suggests that an important part of the disease process is damage to the myelin and brain caused by too much oxygen (sometimes called oxidative stress) or too much inflammation (or swelling). The overall goal of this study will be to determine whether N-acetyl cysteine (NAC) will help to support cerebral function in patients with Multiple Sclerosis (MS). This positron emission tomography magnetic resonance imaging (PET-MRI) study will utilize 18F-2-fluoro-2-deoxy-D-glucose fluorodeoxyglucose positron emission tomography FDG PET to measure cerebral metabolism, along with MRI analysis, to measure metabolism and structural effects of NAC in patients with MS.

    Clinical TrialClinicalTrials.govModerate Quality

  • Effect of N-acetyl Cysteine on Non Alcoholic Fatty Liver Disease in Obese Children

    n=14 · NCT02117700 · COMPLETED · COMPLETED

    Although weight reduction through physical activity-based interventions is the mainstay therapy for nonalcoholic fatty liver disease (NAFLD), its maintenance is difficult and typically unsuccessful. This affirms the extreme need for alternate and/or adjunct therapies. Although convincing data from animal studies and a few adult human studies on the benefits of a natural product, N-acetyl cysteine (NAC), in a variety of liver conditions including NAFLD have emerged, studies in children are scarce. Therefore, the aim of the study is to test the use NAC as an innovative approach to attenuate the progression of NAFD in obese children with biopsy proven NASH. The central hypothesis is that NAC supplementation will reduce liver fat and liver enzymes and ameliorate risk factors of cardiometabolic disease in children with NAFLD.

    Clinical TrialClinicalTrials.govModerate Quality

  • Effect on Migraine Frequency of Combined Anti-oxidant Therapy: N-acetylcysteine, Vitamin E and Vitamin C (NEC): The MIGRANT Study

    n=90 · NCT02629536 · UNKNOWN · UNKNOWN

    Migraine affects 15% of Western Australians and is a leading cause of suffering and disability in our community (1,2). Research suggests that inflammation of the brain's coverings (meninges) by nerve cell inflammation and the release of 'free radicals', is a cause of migraine. N-acetylcysteine, Vitamin E and Vitamin C are powerful anti-oxidants (free-radical scavengers) that reduce brain inflammation and nerve activity. It is therefore possible these anti-oxidants could reduce the number and severity of migraines. We will study 90 subjects to see if a combination of N-acetylcysteine 600 mg, Vitamin E 250 IU and vitamin C 500 mg (NEC) taken twice daily for 3 months, will reduce migraine attacks. This safe vitamin-based therapy has never been studied and if effective, will play an important role in migraine prevention.

    Clinical TrialClinicalTrials.govModerate Quality

Limitations: The absence of provided PubMed studies means a comprehensive assessment of evidence limitations is not possible. Generally, limitations for dietary supplements often include small sample sizes in human trials, heterogeneity in study designs, lack of standardized dosages, and potential for publication bias. Many claims may be based on preliminary research or mechanisms observed in laboratory settings rather than robust clinical outcomes.

Health Voice Perspectives

Independent of evidence grade

Approved mentions from health educators, physicians, and researchers across podcasts, videos, and articles. Educational context only — does not influence the scientific evidence rating above.

  • TH
    Tallene Hacatoryan· MS, RD, CLT — Registered Dietitian

    Uses NAC to support insulin sensitivity, ovulation, and antioxidant defense in PCOS, often alongside inositol.

    "NAC is a quiet workhorse for PCOS — it supports insulin sensitivity and glutathione, which most cysters are running low on."
    ·6/4/2026
  • DB
    Drew Baird· Personal Trainer; Founder, NOVUM PCOS Coaching

    Recommends NAC for PCOS to support insulin sensitivity, ovulation, and antioxidant capacity.

    "NAC is one of those underrated PCOS supplements — it's in the literature for ovulation and insulin, but almost no GP mentions it."
    ·6/4/2026

This page is educational. Statements use phrases like "may support" and "has been studied for"because no remedy here is approved to cure, treat, or reverse any condition. Discussion happens on the ailment pages — community statistics here are derived from those reports. Always consult a qualified clinician.

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