Rankings / Essentials — Supplements
NAC (N-acetyl cysteine)
Essentials · Glutathione precursor / mucolytic
Also known as: Acetylcysteine ·Mucomyst
Tier B+
Bottom line
Read Off Label grades NAC (N-acetyl cysteine) as B+ (7.1/10) based on moderate evidence, moderate benefit magnitude, and a low-risk safety profile.
Core component of the GlyNAC longevity combination (with glycine).
Typical use: 600-1800 mg/day PO divided; higher for acute liver protection — Rx (IV for APAP overdose; Mucomyst); OTC supplement.
What this is
Core component of the GlyNAC longevity combination (with glycine). Reasonable adjunct for respiratory issues and glutathione support; 'detox' marketing exceeds the evidence. Used medically IV for acetaminophen overdose. FDA sent warning letters to Amazon sellers in 2020 claiming NAC was an unapproved drug — triggering industry litigation — then issued a 2022 final rule backing off enforcement, and NAC remains widely sold. Can cause transient nausea at high doses.
Mechanism
Cysteine prodrug; replenishes glutathione (rate-limited by cysteine availability); mucolytic via disulfide bond reduction; glutamate modulation in brain; anti-inflammatory; FDA-approved for acetaminophen overdose and as mucolytic
Dose & route
600-1800 mg/day PO divided; higher for acute liver protection
Citations
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8774421/
- https://pubmed.ncbi.nlm.nih.gov/25234283/
- https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD001287.pub6/full
- https://pubmed.ncbi.nlm.nih.gov/40806713/
- https://pubmed.ncbi.nlm.nih.gov/41008940/
- https://pubmed.ncbi.nlm.nih.gov/30653687/
- https://www.fda.gov/media/155675/download
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8017281/
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Common questions
- Does NAC (N-acetyl cysteine) work?
- Read Off Label rates the evidence for NAC (N-acetyl cysteine) as Moderate and the benefit magnitude as moderate, producing an overall grade of B+ (7.1/10). Core component of the GlyNAC longevity combination (with glycine).
- Is NAC (N-acetyl cysteine) safe?
- NAC (N-acetyl cysteine) has a low risk profile in published human data. Legal status: Rx (IV for APAP overdose; Mucomyst); OTC supplement (restored after FDA 2022 decision not to pursue enforcement action after 2020 warning letters). This is not medical advice — see the disclaimer.
- What is the typical dose for NAC (N-acetyl cysteine)?
- 600-1800 mg/day PO divided; higher for acute liver protection
- How does NAC (N-acetyl cysteine) work?
- Cysteine prodrug; replenishes glutathione (rate-limited by cysteine availability); mucolytic via disulfide bond reduction; glutamate modulation in brain; anti-inflammatory; FDA-approved for acetaminophen overdose and as mucolytic
This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.