library.onepin.app/nac-n-acetyl-cysteine Peptide Education Library
Education only, not medical advice 21+ Every dose is an example to finalize with a licensed provider

OnePin Peptide Library · Mitochondrial

Mitochondrial Peptide Prescription drug

NAC (N-Acetyl Cysteine)

N-Acetyl Cysteine · N-Acetyl-L-Cysteine

N-Acetyl Cysteine (NAC) is an acetylated derivative of the conditionally essential amino acid L-cysteine. It serves as a direct precursor to glutathione (GSH) - the body's primary intracellular antioxidant. By providing the rate-limiting substrate for glutathione synthesis, NAC indirectly elevates reduced glutathione levels across tissues, including the liver, brain, and lung.,NAC has been used medically since the 1960s, primarily as a mucolytic agent (loosens mucus in respiratory conditions) and as the standard antidote for acetaminophen (paracetamol) overdose. In integrative medicine, NAC is widely used for liver support, respiratory health, mental health (OCD, depression, addictive behaviors), fertility, and as a general antioxidant/anti-inflammatory.,NAC's pleiotropic effects span multiple organ systems: it replenishes glutathione, directly scavenges reactive oxygen species, modulates glutamate signaling in the brain, reduces inflammation, and may improve mitochondrial function. It is one of the few supplements with FDA-approved medical indications alongside dietary supplement use.

Quick Start
Route
Oral
Start low
600mg 1-2x daily
Frequency
1-3x daily with or between meals
Timing
Anytime

Can be taken with or without food; better absorbed on empty stomach but GI tolerance improves with food. Split dosing recommended for doses >1,200mg/day. For mucolytic effect, take 600-1,200mg morning + evening.

Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.

Tiered Protocols · lowest first
Quick Start
Conservative start
600mg 1-2x daily · Oral · 1-3x daily with or between meals
Lowest starting point. Hold about a week to assess tolerance before stepping up.
600mg 1-2x daily
1-3x daily with or between meals
Standard
Glutathione Precursor
600-1200 mg · Oral · Daily
human clinical trial · Berk et al. 2008 (Biol Psychiatry 2008;64(6):468-475)
600-1200 mg
Daily
01

How it works

NAC deacetylates in the intestine and liver to release L-cysteine, the rate-limiting amino acid for glutathione (GSH) biosynthesis. Glutathione is the body's master antioxidant, present in millimolar concentrations intracellularly, and directly neutralizes reactive oxygen species, detoxifies xenobiotics via glutathione-S-transferases, and maintains protein thiol redox state.,NAC directly reduces disulfide bonds in mucoproteins, breaking up thick mucus and providing its mucolytic effect in respiratory conditions. NAC also scavenges free radicals directly via its thiol group, independent of GSH synthesis.,In the brain, NAC modulates the glutamate system by restoring extracellular glutamate homeostasis via the cystine-glutamate antiporter (xCT). Elevated cystine exchange drives glutamate into synaptic clefts, activating metabotropic glutamate receptors and normalizing pathologically elevated or depressed glutamate transmission. This underlies its use in OCD, addiction, trichotillomania, and depression.,NAC also downregulates NF-kB signaling, reducing inflammatory cytokine production. In the liver, it binds reactive metabolites of acetaminophen (NAPQI), preventing hepatotoxicity - the basis for its FDA-approved emergency use.

NAC deacetylates in the intestine and liver to release L-cysteine, the rate-limiting amino acid for glutathione (GSH) biosynthesis. Glutathione is the body's master antioxidant, present in millimolar concentrations intracellularly, and directly neutralizes reactive oxygen species, detoxifies xenobiotics via glutathione-S-transferases, and maintains protein thiol redox state.,NAC directly reduces disulfide bonds in mucoproteins, breaking up thick mucus and providing its mucolytic effect in respiratory conditions. NAC also scavenges free radicals directly via its thiol group, independent of GSH synthesis.,In the brain, NAC modulates the glutamate system by restoring extracellular glutamate homeostasis via the cystine-glutamate antiporter (xCT). Elevated cystine exchange drives glutamate into synaptic clefts, activating metabotropic glutamate receptors and normalizing pathologically elevated or depressed glutamate transmission. This underlies its use in OCD, addiction, trichotillomania, and depression.,NAC also downregulates NF-kB signaling, reducing inflammatory cytokine production. In the liver, it binds reactive metabolites of acetaminophen (NAPQI), preventing hepatotoxicity - the basis for its FDA-approved emergency use.

02

What to expect

Early
Days 1–7

Weeks 1-2: Sulfur odor adaptation, respiratory mucolytic effect noticeable if present.

03

Evidence

HumanPresent
AnimalPresent
In-vitroPresent
2009N-acetylcysteine, a glutamate modulator, in the treatment of trichotillomania: a double-blind, placebo-controlled study · Grant JE et al, Archives of General Psychiatry ↗peer reviewed
2008N-acetyl cysteine as a glutathione precursor for schizophrenia - a double-blind, randomized, placebo-controlled trial · Berk M et al, Biological Psychiatry ↗peer reviewed
2008N-acetyl cysteine for depressive symptoms in bipolar disorder - a double-blind randomized placebo-controlled trial · Berk M et al, Biological Psychiatry ↗peer reviewed
2005Effects of N-acetylcysteine on outcomes in chronic obstructive pulmonary disease (Bronchitis Randomized on NAC Cost-Utility Study, BRONCUS) · Decramer M et al, The Lancet ↗peer reviewed
04

Interactions & stacking

What's safe to combine, and what belongs in a separate pin.

Safe & synergistic

SSRIs/SNRIsNAC is well-studied as adjunct to antidepressants for OCD, depression, bipolar - evidence supports complementary mechanism.
StatinsMay reduce statin-induced oxidative stress and muscle symptoms in some patients. Compatible co-administration.
GlycineGlycine is also a glutathione synthesis precursor. The GlyNAC combination (glycine + NAC) shown in trials to more fully restore GSH synthesis than NAC alone, particularly in older adults.
SeleniumSelenium is a cofactor for glutathione peroxidase. Adequate selenium status is required for glutathione to function as an antioxidant. Synergistic for oxidative stress.

Keep separate

NitroglycerinNAC potentiates nitroglycerin's vasodilatory and hypotensive effects - can cause severe headache and hypotension. Avoid combination.
Activated charcoalCharcoal binds NAC and prevents absorption - space dosing 2+ hours apart. Not a long-term concern unless routinely using charcoal.
Chemotherapy (case-by-case)Antioxidants may theoretically interfere with chemotherapy-induced oxidative stress on tumor cells. Discuss with oncologist; do not stop or start NAC during active chemotherapy without consultation.
05

Pharmacokinetics

Illustrative plasma concentration · 24 h
Half-life
~5-6 hours plasma (acetylated form); intracellular cysteine and glutathione elevation persists longer (~12-24 hours).
Peak · Tmax
~1-2 hours oral; ~30 min IV.
Elimination
~24 hours for most systemic effects; tissue glutathione levels restored over days-weeks of chronic dosing.
Activity
Acute mucolytic/antioxidant effects: 6-12 hours. Chronic GSH elevation: persists 2-3 days after last dose. Mental health effects (OCD, depression) require 8-12 weeks of consistent dosing to manifest.

Storage. Store at room temperature (15-30C) in a cool, dry place. Protect from moisture. Capsules shelf-stable 2+ years. Some sulfur odor is normal and does not indicate degradation.

06

Regulatory status

Has dual status: FDA-approved prescription drug (Mucomyst, Acetadote) for mucolytic and acetaminophen overdose indications. Also widely sold as dietary supplement. FDA issued 2020 warning letters questioning supplement status, but enforcement discretion continues to allow OTC sales. Status remains ambiguous.

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