We use essential cookies (authentication, your saved goals/stack) by default. With your permission we'll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more
N-Acetyl Cysteine
Rate-limiting precursor to glutathione, the body's master antioxidant — supports mood, respiratory health, and liver protection.
What the evidence says
NAC appears to help in 8 of 9 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 2015–2026 with a typical study size of 701 participants.
Based on 40 studies · 22 meta-analyses · 4 RCTs · 20,122 total participants
Confidence
HighWhat the studies found
By outcome
See full supplement plans that include NAC.
NAC has an evidence score of 8/10 — strong evidence based on 40 indexed studies, including 30 meta-analyses. Rate-limiting precursor to glutathione, the body's master antioxidant — supports mood, respiratory health, and liver protection.
The commonly studied dose of NAC is 600-1800mg daily. Research points to an estimated optimal dose around 1800mg, with a minimum effective dose near 1200mg. Individual response varies — start low and adjust.
The best time to take NAC is between meals. It can be taken on an empty stomach. N-acetyl cysteine is a derivative of the amino acid L-cysteine and the rate-limiting precursor to glutathione synthesis.
Last reviewed May 2026 · evidence from 38 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
N-Acetyl Cysteine (NAC) is the supplemental form of the amino acid cysteine and the rate-limiting precursor to glutathione, the body's master antioxidant. Research supports its use for mood disorders, respiratory health, liver protection, and oxidative stress reduction.
Replenishes the body's master antioxidant
Regulates excitatory neurotransmission
Breaks down mucus in airways
How NAC works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
600-1800mg daily
Can be taken without food
| Form | Type |
|---|---|
| 💊NAC capsules or powder | Recommended |
| 💊Effervescent tablets | Alternative |
| 💊Sustained-release | Alternative |
Standard NAC is well-absorbed. Sustained-release may reduce GI issues. Some use with vitamin C to prevent oxidation.
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: Best absorbed on empty stomach, but can cause nausea. If GI issues occur, take with light meal. Split doses for higher amounts.
Meta-analysis showed efficacy particularly in bipolar disorder patients. Effect appears as adjunctive treatment. Individual response varies significantly.
Reduced symptoms of depression
Enhanced glutathione levels and protection
Reduced mucus and easier breathing
Can cause nausea if not taken properly
Used clinically for acetaminophen overdose in pregnancy; supplements less studied
Use caution; may cause bronchospasm in some individuals
May enhance vasodilatory effects; can cause severe headache
May have mild antiplatelet effects — may affect platelet aggregation or vitamin K-dependent clotting factors, altering anticoagulant efficacy
May reduce NAC absorption
Tip: Take with food; reduce dose
Tip: Normal; can use capsules instead of powder
Tip: Reduce dose
Vitamin C helps regenerate glutathione
Enhanced antioxidant recycling
Both support mood through different mechanisms
Comprehensive mood and antioxidant support
Both support glutathione and liver health
Comprehensive liver support and detoxification
Both thin mucus through different mechanisms
Comprehensive respiratory mucus support
NAC supports glutathione; TUDCA reduces ER stress
Multi-pathway liver protection
NAC is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are nausea, sulfur smell/taste, diarrhea. Use caution if any of these apply to you: Asthma (may cause bronchospasm in some); Bleeding disorders.
Taurine
Likely helpsConcentrated in heart, brain, and muscle — emerging longevity data alongside proven benefits for sleep, cardiovascular function, and recovery.
Tap node to isolate • Pinch to zoom • Tap edge for research