NAC (N-Acetyl Cysteine)
The acetylated form of the amino acid L-cysteine and the most effective oral supplement for raising glutathione — the body's master antioxidant. NAC has an unusually broad range of evidence-based applications: it is used as a prescription drug for acetaminophen overdose, as a mucolytic, and as an adjunct treatment for OCD, addiction, and bipolar disorder. In nootropics, it protects neurons from oxidative stress and modulates glutamate.
Dosage
Standard: 600-1800 mg daily in 2-3 divided doses. For psychiatric applications: 1200-2400 mg daily (under medical supervision). Take on an empty stomach for best absorption. Can cause nausea — take with a small amount of food if needed.
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Half-Life
5.6 hours
Administration
Oral (capsules, powder). Take on empty stomach or with light food. Effervescent tablets also available.
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Mechanism of Action
NAC provides cysteine, the rate-limiting substrate for glutathione (GSH) synthesis via gamma-glutamylcysteine ligase (GCLC) and glutathione synthetase (GSS). GSH is the primary intracellular antioxidant, essential for GPx and GST-mediated detoxification of reactive oxygen species in neurons. NAC also modulates glutamate via the cystine-glutamate antiporter (System Xc-, composed of xCT and 4F2hc) — NAC is deacetylated to cysteine, which exchanges for glutamate; the increased extracellular cystine is reduced to cysteine intracellularly, while the exchange increases extrasynaptic glutamate, which activates inhibitory mGlu2/3 autoreceptors on presynaptic terminals, reducing excessive glutamatergic signaling and compulsive behaviors. This glutamate modulation is the basis for psychiatric applications (OCD, addiction). NAC may also directly modulate NMDA receptors via redox sites.
Regulatory Status
Prescription drug (acetaminophen overdose, mucolytic) and dietary supplement. FDA attempted to restrict supplement status in 2022 but reversed course. Available OTC.
Risks & Safety
Common
Nausea, diarrhea, unpleasant sulfur smell/taste.
Serious
May be harmful in certain contexts — there is concern it could protect cancer cells from oxidative stress. May interact with nitroglycerin (dangerous blood pressure drop).
Rare
Bronchospasm in asthmatics (when inhaled).
Compare NAC (N-Acetyl Cysteine) With
Research Papers
10Published: April 27, 2021
AI Summary
The results indicated that LC/LAC and NAC had a considerable improvement in sperm motility (p = .03 and p < .0001, respectively) and normal morphology (p = .006, p = .0002, respectively) compared with the placebo group. Besides, NAC had a significantly greater increase in sperm concentration (p < .00001) and ejaculate volume (p = .
Published: February 28, 2019
AI Summary
N-acetyl cysteine (NAC) is a thiolic antioxidant that is thought to increase cellular glutathione (GSH) by augmenting the concentration of available cysteine, an essential precursor to GSH production. Manipulating redox status can affect brain function, and NAC intake has been associated with improv
Published: March 5, 2019
AI Summary
The aim of the present study was to evaluate the effect of acetyl-l-carnitine (ALC) and N-acetyl cysteine (NAC) on ionizing radiation (IR)-induced cytotoxicity and change in DNA damage-related genes in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells.
Published: July 16, 2012
AI Summary
In contrast, the microglial reaction was significantly attenuated. The results indicate a therapeutic potential for NAC and ALC in the early treatment of traumatic spinal cord injury.
Published: June 5, 2014
AI Summary
Spinal cord hemisection performed at the level C3 induced a significant loss of rubrospinal neurons 8 weeks after injury. After 8 weeks, treatment decreased immunoreactivity for OX42, whereas it was increased for 5HT.
Published: October 22, 2019
AI Summary
Accumulating evidence shows that a propensity towards a pro-inflammatory status in the brain plays an important role in schizophrenia. This study provides an update regarding the efficacy of agents with some anti-inflammatory actions for schizophrenia symptoms tested in randomized controlled trials (RCTs).
Published: June 13, 2025
AI Summary
N-acetylcysteine (NAC) and acetyl-L-carnitine (ALC) are two supplements that have already been found effective in treating psychiatric conditions. Furthermore, NAC showed evidence in relieving cognitive symptomatology in PCS, and ALC was found effective in treating depressive symptomatology of PCS.
Published: April 29, 2024
AI Summary
Abstract too short to summarize.
Published: September 30, 1995
AI Summary
The role of regenerative processes in the protective effect of N-acetyl-L-cysteine (NAC) against bromoethylamine-induced renal papillary necrosis was assessed in rats given bromoethylamine (BEA)(1.2 mmol/kg), N-acetylcysteine (6 mmol/kg), or N-acetyl-cysteine plus BEA.
Published: October 6, 2010
AI Summary
This review critically discusses drugs used to treat seizures after hypoxia-ischemia in the neonate with attention to evidence of possible synergies for therapy. Finally, compounds that might damage the developing brain or counteract the neuroprotective effects of hypothermia are discussed.
Frequently Asked Questions
What is NAC (N-Acetyl Cysteine) used for?
The acetylated form of the amino acid L-cysteine and the most effective oral supplement for raising glutathione — the body's master antioxidant. NAC has an unusually broad range of evidence-based applications: it is used as a prescription drug for acetaminophen overdose, as a mucolytic, and as an adjunct treatment for OCD, addiction, and bipolar disorder. In nootropics, it protects neurons from oxidative stress and modulates glutamate.
What are the side effects of NAC (N-Acetyl Cysteine)?
Common: Nausea, diarrhea, unpleasant sulfur smell/taste. Serious: May be harmful in certain contexts — there is concern it could protect cancer cells from oxidative stress. May interact with nitroglycerin (dangerous blood pressure drop). Rare: Bronchospasm in asthmatics (when inhaled).
How is NAC (N-Acetyl Cysteine) administered?
NAC (N-Acetyl Cysteine) is administered via oral (capsules, powder). take on empty stomach or with light food. effervescent tablets also available..
What is the half-life of NAC (N-Acetyl Cysteine)?
The half-life of NAC (N-Acetyl Cysteine) is 5.6 hours.
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