What is N-Acetylcysteine (NAC)?

N-Acetylcysteine (NAC) is a synthetic derivative of the amino acid cysteine. It helps replenish glutathione and is also used as a mucolytic to thin mucus.

What are the main benefits of NAC?

NAC is commonly used to support respiratory health by loosening mucus and to support antioxidant defenses by boosting glutathione. It is also used medically to protect the liver in acetaminophen toxicity.

What is a typical NAC dosage?

Common supplemental doses are often in the range of 600–1800 mg per day, depending on the goal and product. Follow label directions and consult a clinician for personalized dosing.

Is NAC safe, and who should be cautious?

NAC is generally well tolerated, but some people may experience gastrointestinal upset. People who are pregnant or breastfeeding, have asthma, or take medications should consult a healthcare professional before use.

Can NAC help with mental health or PCOS?

NAC is sometimes used as an adjunct for mood-related conditions and for metabolic support in PCOS, likely related to oxidative stress and insulin sensitivity. Evidence varies by condition, so it should not replace standard care.

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N-Acetylcysteine

Strong study situation·10/10

A higher score indicates better study conditions, but not necessarily effectiveness.

The versatile antioxidant and glutathione booster with life-saving and emerging psychiatric benefits.

PCOS Anti-inflammatory Antioxidant Depression / Mood Enhancement Neuroprotective Liver Health Respiratory Health

dose range

600–1800 mg

2x daily

Consumption

Take orally with water; dilute oral solution if using liquid form.

Not fat-soluble.

Best time

Can be taken with or without food; dividing doses reduces GI side effects.

Description

N-Acetylcysteine (NAC) is a powerful amino acid derivative best known for saving lives in acetaminophen overdoses and serving as a precursor to the body’s master antioxidant, glutathione. Latest research reveals NAC’s remarkable benefits extend to mental health, chronic disease prevention, and tissue repair, operating through multiple sophisticated biochemical pathways. Its growing evidence base and strong safety record make it an intriguing choice for targeted supplementation.

Natural Food Sources

Non-exhaustive list of the most nutrient-dense natural sources

Roasted chicken leg740 mg cysteine / 100gCysteine precursor for NAC and glutathione

Braised lamb721 mg cysteine / 100g

Grilled pork tenderloin644 mg cysteine / 100g

Roasted goose636 mg cysteine / 100g

Boiled egg480 mg cysteine / 100g

Raw oats636 mg cysteine / 100g

Oat bran541 mg cysteine / 100g

Boiled soybeans (edamame)461 mg cysteine / 100g

Cooked lentils234 mg cysteine / 100g

benefits

Main effects with level of evidence

Strong

Note on evidence

Strong evidence for acetaminophen toxicity and established medical uses; growing but moderate evidence for respiratory and psychiatric roles; other uses require further large studies.

Acetaminophen Toxicity Antidote

Strong

NAC is the gold-standard, FDA-approved treatment for acetaminophen (paracetamol) overdose, preventing liver failure and reducing mortality if given within 8 hours. Its effectiveness is nearly 100% when administered promptly, working by restoring glutathione and detoxifying harmful metabolites.

Particularly relevant for: adults · children · emergency medicine

S1 · NIH LiverTox – AcetylcysteineS2 · Prescott LF. Paracetamol overdosage. Pharmacological basis of treatment. Br J Clin Pharmacol. 1980 Apr;10(S2):291S–298S.S3 · Smilkstein, M.J., et al. (1988). Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. New England Journal of Medicine, 319(24), 1557-1562.

Chronic Respiratory Disease Relief

Moderate

High-dose NAC (≥1,200 mg/day) reduces COPD exacerbations, improves mucus clearance, and raises lung antioxidant capacity, especially with long-term use. Benefits are most pronounced in moderate to severe COPD and in cystic fibrosis, showing reduced exacerbation rates and improved small airway function.

Particularly relevant for: adults · elderly · chronic lung disease

S4 · Meta-analysis: NAC in COPD (Zhou XY et al. 2014)S5 · Gao et al. PANTHEON trial—NAC in chronic obstructive pulmonary disease.S6 · Braga PC et al. HIACE trial—NAC in COPD.

Mental Health & Psychiatric Disorders

Moderate

Clinical trials show NAC can improve symptoms in bipolar disorder, schizophrenia, obsessive-compulsive disorder, trichotillomania, and autism spectrum disorder through anti-inflammatory, antioxidant, and glutamatergic modulation mechanisms. Reductions in depression scores, negative symptoms, and compulsive behaviors have been documented, though more large-scale trials are needed.

Particularly relevant for: adults · adolescents · mental health

S7 · Berk M, et al. (2008). N-acetyl cysteine as a glutathione precursor for schizophrenia—a double-blind, randomized, placebo-controlled trial. Biol Psychiatry.S8 · Dean OM et al. NAC in bipolar disorder: A randomized controlled trial. Biol Psychiatry. 2008.S9 · NIH MedlinePlus – NAC Supplement Info S10 · FDA NAC Drug Label (Mucomyst/Acetadote)

Kidney Protection & Cardiovascular Support

Moderate

NAC helps prevent contrast-induced nephropathy during imaging, reduces cardiovascular events in chronic kidney disease, and may protect the heart during reperfusion procedures. These benefits are supported by meta-analyses showing improved renal function and reduced inflammation.

Particularly relevant for: CKD patients · hospitalized patients · heart disease risk

S11 · Zhao L, et al. NAC in chronic kidney disease—a systematic review and meta-analysis.S12 · NACIAM Trial (NAC in Acute MI)—Pasupathy S, et al.S13 · Akimoto T, et al. Contrast nephropathy and NAC.

Fertility Enhancement in PCOS

Moderate

NAC improves ovulation, live birth rates, and hormone balance in women with polycystic ovary syndrome, especially when used alongside clomiphene in resistant cases. It may also reduce insulin resistance and serum androgens.

Particularly relevant for: women · fertility patients · PCOS

S14 · Salehpour S, et al. N-acetylcysteine in PCOS: A meta-analysis.

Safety & Information

Important safety information & known risks

For educational purposes only • not medical advice

NAC is generally safe and well-tolerated when used as directed, with most side effects being mild and gastrointestinal. Rare but serious reactions include anaphylactoid reactions with IV use, bronchospasm in asthmatics, and, in overdose, risk of serious toxicity. Bleeding risk and drug interactions warrant caution in susceptible individuals.

warning notices

Common side effects: nausea, diarrhea, headache, sulfurous odor.
Rare anaphylactoid reactions with IV NAC—less common orally.
Potential for bronchospasm in people with asthma.
Risk of bleeding—discontinue before surgery.
Do not use as a general preventive supplement in cancer-prone individuals without medical supervision.
Discontinue at least 2 weeks before surgery due to bleeding risk.
Seek immediate medical supervision for overdose or severe allergic reaction.

Known interactions with medications

May increase effects and side effects of nitroglycerin (hypotension, headache).
Can lower carbamazepine blood levels; monitor in epilepsy.
Interferes with some antibiotics and activated charcoal; separate dosing.
Caution with immunosuppressants, corticosteroids, and bleeding risk medications.

Contraindications / special precautions

Active peptic ulcer disease (for oral forms).
Known hypersensitivity to NAC.
Uncontrolled asthma (oral/inhaled use).

interactions

Important interactions between active ingredient ↔ supplement / medication / food

NAC can increase the effects and side effects of nitroglycerin, decrease blood levels of some anticonvulsants, and interfere with certain antibiotics and immunosuppressants. It may slow blood clotting and pose risk for those prone to bleeding.

Monitor for low blood pressure with nitroglycerin

drug · Nitroglycerin

CautionStrong

Why

NAC can increase the vasodilatory effects and risk of hypotension when taken with nitroglycerin.

recommendation

Use with caution, monitor blood pressure, and avoid sudden position changes.

S9 · NIH MedlinePlus – NAC Supplement Info S10 · FDA NAC Drug Label (Mucomyst/Acetadote)

Monitor anticonvulsant levels with NAC use

drug · Carbamazepine

MonitorLimited

Why

NAC may lower blood levels of carbamazepine, potentially reducing seizure control.

recommendation

Test drug levels regularly and adjust dose as needed.

S10 · FDA NAC Drug Label (Mucomyst/Acetadote)

Separate certain antibiotics from NAC

drug · Oxytetracycline, Tetracycline, Trypsin

SeparateLimitedSeparate by at least 2 hours.

Why

May reduce antibiotic efficacy when taken together.

recommendation

Space doses by at least 2 hours.

S20 · Memorial Sloan Kettering Cancer Center: NAC Drug Interactions

Take NAC and activated charcoal apart

nutrient · Activated Charcoal

SeparateTheoreticalActivated CharcoalSeparate by 2+ hours.

Why

Charcoal can bind NAC and prevent its absorption.

recommendation

Take at least 2 hours apart.

S20 · Memorial Sloan Kettering Cancer Center: NAC Drug Interactions

Medical supervision needed when combined with immunosuppressants

drug · Immunosuppressants (e.g., azathioprine, cyclophosphamide)

AdjustLimited

Why

Potential interactions may alter effectiveness or side effects.

recommendation

Consult healthcare provider for dose adjustments.

S20 · Memorial Sloan Kettering Cancer Center: NAC Drug Interactions

Supervise use of NAC with corticosteroids

drug · Prednisone

MonitorLimited

Why

Possible interaction with corticosteroids, though evidence is limited.

recommendation

Monitor for unusual effects.

S20 · Memorial Sloan Kettering Cancer Center: NAC Drug Interactions

Caution: may increase bleeding risk

drug · Bleeding Disorders or Anticoagulants

CautionModerateStop 2+ weeks pre-surgery.

Why

NAC can slow blood clotting.

recommendation

Discontinue at least 2 weeks before surgery; monitor for excess bruising.

S9 · NIH MedlinePlus – NAC Supplement Info S10 · FDA NAC Drug Label (Mucomyst/Acetadote)

Monitor closely in asthmatics—risk of bronchospasm

lifestyle · Asthma (airway hyperreactivity)

CautionStrong

Why

Inhaled or oral NAC may trigger bronchospasm in sensitive individuals.

recommendation

Use only under medical supervision.

S9 · NIH MedlinePlus – NAC Supplement Info S10 · FDA NAC Drug Label (Mucomyst/Acetadote)

mechanisms of action

Brief explanations of how it works

Glutathione Precursor and Antioxidant

NAC supplies cysteine, the limiting substrate for glutathione biosynthesis, increasing intracellular GSH and thus enhancing detoxification and antioxidative capacity, especially in oxidative-stress-related diseases.

S1 · NIH LiverTox – Acetylcysteine S3 · Smilkstein, M.J., et al. (1988). Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. New England Journal of Medicine, 319(24), 1557-1562.S15 · Aruoma OI, Halliwell B, Hoey BM, Butler J. The antioxidant action of N-acetylcysteine: its reaction with hydrogen peroxide, hydroxyl radical, superoxide, and hypochlorous acid. Free Radic Biol Med. 1989.

Hydrogen Sulfide and Sulfane Sulfur Pathways

NAC-derived cysteine can generate hydrogen sulfide and sulfane sulfur species, providing potent mitochondrial antioxidant and cytoprotective effects independent of glutathione.

S15 · Aruoma OI, Halliwell B, Hoey BM, Butler J. The antioxidant action of N-acetylcysteine: its reaction with hydrogen peroxide, hydroxyl radical, superoxide, and hypochlorous acid. Free Radic Biol Med. 1989.S16 · Kimura H. Signaling molecules: hydrogen sulfide and polysulfide. Antioxid Redox Signal. 2014.

Anti-inflammatory and Immune Modulation

NAC suppresses NF-κB, reducing production of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β), and helps modulate immune and inflammatory responses in chronic and psychiatric conditions.

S6 · Braga PC et al. HIACE trial—NAC in COPD.S7 · Berk M, et al. (2008). N-acetyl cysteine as a glutathione precursor for schizophrenia—a double-blind, randomized, placebo-controlled trial. Biol Psychiatry.

Glutamatergic Modulation

Through the cystine/glutamate antiporter (System xc⁻), NAC balances extracellular glutamate, supporting healthy neurotransmission and reducing compulsive or psychotic behaviors.

S8 · Dean OM et al. NAC in bipolar disorder: A randomized controlled trial. Biol Psychiatry. 2008.S9 · NIH MedlinePlus – NAC Supplement Info

Sources & References

Primary literature and reviews on which these statements are based

17 sources

NIH LiverTox – Acetylcysteine

Prescott LF. Paracetamol overdosage. Pharmacological basis of treatment. Br J Clin Pharmacol. 1980 Apr;10(S2):291S–298S.

Smilkstein, M.J., et al. (1988). Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. New England Journal of Medicine, 319(24), 1557-1562.

Meta-analysis: NAC in COPD (Zhou XY et al. 2014)

Gao et al. PANTHEON trial—NAC in chronic obstructive pulmonary disease.

Braga PC et al. HIACE trial—NAC in COPD.

Berk M, et al. (2008). N-acetyl cysteine as a glutathione precursor for schizophrenia—a double-blind, randomized, placebo-controlled trial. Biol Psychiatry.

Dean OM et al. NAC in bipolar disorder: A randomized controlled trial. Biol Psychiatry. 2008.

NIH MedlinePlus – NAC Supplement Info

S10

FDA NAC Drug Label (Mucomyst/Acetadote)

S11

Zhao L, et al. NAC in chronic kidney disease—a systematic review and meta-analysis.

S12

NACIAM Trial (NAC in Acute MI)—Pasupathy S, et al.

S13

Akimoto T, et al. Contrast nephropathy and NAC.

S14

Salehpour S, et al. N-acetylcysteine in PCOS: A meta-analysis.

S15

Aruoma OI, Halliwell B, Hoey BM, Butler J. The antioxidant action of N-acetylcysteine: its reaction with hydrogen peroxide, hydroxyl radical, superoxide, and hypochlorous acid. Free Radic Biol Med. 1989.

S16

Kimura H. Signaling molecules: hydrogen sulfide and polysulfide. Antioxid Redox Signal. 2014.

S20

Memorial Sloan Kettering Cancer Center: NAC Drug Interactions

Last updated: April 7, 2026

This information is for educational purposes only and does not replace medical advice.