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Amino Acid

N-Acetyl L-Cysteine (NAC)

Also known as: NAC, N-acetylcysteine, acetylcysteine, vegan NAC

B
Evidence

NAC is a stabilized form of the amino acid L-cysteine that serves as a precursor to glutathione, a major intracellular antioxidant. It has strong evidence for respiratory health and moderate evidence for immune and detoxification support.

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Daily target & upper limit

600 mg / day

N-Acetyl L-Cysteine (NAC) has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:

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Primary uses

  • Antioxidant support via glutathione synthesis
  • Respiratory health and mucolytic action
  • Immune function support
  • Liver detoxification
  • Acetaminophen toxicity management (clinical use)

How it works

  • Replenishes glutathione stores via cysteine donation
  • Directly scavenges reactive oxygen species
  • Breaks down mucus protein bonds (mucolytic effect)
  • Supports phase II liver detoxification enzymes

Dosage

Typical range
600-1200 mg daily (divided into 2-3 doses)
Timing
Can be taken any time of day; consistency matters more than timing
With food
May be taken with or without food; taking with food may reduce stomach upset
Duration
Generally safe for long-term use; clinical protocols often use 600-1800 mg daily
Special populations
Doses up to 1500 mg daily have been used in respiratory studies; those with cystinuria should avoid supplementation

Forms

  • capsule· 70/100
  • powder· 70/100
  • tablet· 70/100

Safety

Common side effects

  • Nausea or upset stomach (mild)
  • Diarrhea
  • Constipation
  • Headache (rare)
  • Rash (rare)

Contraindications

  • Cystinuria (genetic condition affecting cysteine handling)
  • Caution in those prone to kidney stones
  • Warrants medical consultation if pregnant or nursing

Products containing N-Acetyl L-Cysteine (NAC)

Top-scoring supplements in our catalog that list N-Acetyl L-Cysteine (NAC) on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.

Nutricost
N-Acetyl L-Cysteine (NAC) Capsules
77
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Evidence notes

Strong clinical evidence for acute respiratory conditions and acetaminophen overdose; moderate evidence for chronic respiratory support and general antioxidant benefits; good safety profile with extensive research history.

Grade B: Some human trials support key claims; further confirmation needed.

Cited research for N-Acetyl L-Cysteine (NAC)

Clinical studies referenced across Formulate guides that mention n-acetyl l-cysteine (nac). Each links to the full study page with PubMed source + the guides that cite it.

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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider.