Home / Ingredient Directory / NAC (N-Acetyl Cysteine)
Yannis Lopez
Reviewed by Yannis Lopez · Nutrition Industry Veteran
Last updated: July 6, 2026
Antioxidant & Respiratory Glutathione Precursor

NAC (N-Acetyl Cysteine)

Antioxidant & glutathione support

Precursor to glutathione
Used in hospitals for decades

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Always consult your physician before starting any supplement.

Overview

N-Acetyl Cysteine (NAC) is a stable form of the amino acid cysteine. It is a powerful precursor to glutathione, the body's master antioxidant. NAC has been used in hospitals for decades as a mucolytic (to break up mucus) and as an antidote for acetaminophen (Tylenol) overdose.

In recent years, NAC has gained popularity as a supplement for antioxidant support, respiratory health, liver support, and mood. It is one of the most researched amino acid derivatives available.

Potential Benefits

Antioxidant Support

NAC is a precursor to glutathione, the body's most important antioxidant. It helps replenish glutathione levels, especially during times of stress or illness.

Respiratory Health

NAC has mucolytic properties, helping to break up mucus and support clear airways. It is commonly used for respiratory support.

Liver Support

NAC supports liver detoxification pathways and is the standard treatment for acetaminophen overdose in hospitals.

Generally Well Tolerated

NAC is very safe with a long history of medical use. Some people may experience mild nausea at higher doses.

Typical Dosage
Daily Dose
600–1,200mg
Often taken in divided doses (600mg 1–2x daily)
Best Taken
With or without food
Can be taken morning and/or evening
Pro Tips
  • Start with 600mg and increase if needed
  • Can be stacked with Alpha Lipoic Acid
  • Take consistently for antioxidant benefits
  • Consult a doctor if you have asthma
Research Snapshot

NAC has decades of clinical research supporting its use for antioxidant support, respiratory health, and liver protection. A 2015 meta-analysis of 13 studies in over 4,000 COPD patients found that NAC significantly reduced the frequency of chronic bronchitis or COPD exacerbations, with higher doses showing greater benefit. It is one of the most studied amino acid derivatives in medicine.

How NAC Compares

Ingredient Best For Key Difference
NAC (N-Acetyl Cysteine) Glutathione, Antioxidant, Respiratory Precursor to glutathione; mucolytic
Alpha Lipoic Acid Antioxidant, Nerve Comfort Works in water and fat environments
Vitamin C Daily immune support, Antioxidant Water-soluble; excess is excreted

NAC pairs very well with Alpha Lipoic Acid for comprehensive antioxidant support.

Popular Stacks with NAC
Antioxidant Foundation Stack
NAC + Alpha Lipoic Acid + Vitamin C
Most popular daily antioxidant combination
Respiratory Support Stack
NAC + Quercetin + Vitamin D3
Popular during cold and flu season
Liver Support Stack
NAC + Milk Thistle + Alpha Lipoic Acid
Great for detoxification support

Full stack recommendations coming soon in our Stacks section.

Frequently Asked Questions
Is NAC the same as cysteine?
No. NAC is a more stable, bioavailable form of cysteine. Your body converts NAC into cysteine, which is then used to make glutathione.
Can I take NAC every day?
Yes. NAC is generally considered safe for daily use at recommended doses. Many people take it long-term for antioxidant and respiratory support.
Will NAC make me smell like sulfur?
Some people notice a mild sulfur-like smell or taste, especially at higher doses. This is normal and harmless. Taking it with food can help minimize this.
Sources & References
Related Ingredients
Alpha Lipoic Acid
Antioxidant support
Vitamin C
Immune & antioxidant
Milk Thistle
Liver support
Glutathione
Master antioxidant
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