Compound or practice · Supplement

N-Acetylcysteine (NAC)

A glutathione precursor with real mucolytic and psychiatric-adjunct evidence — and the antidote for acetaminophen overdose.

Overall grade: Grade B
Last revised: Jul 10, 2026; 3
graded outcomes: 0
references listed

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A structured monograph in Prometheus's bundled library. Its grades are the monograph's own reading of the evidence, not a peer-reviewed review.

1 at grade A · 2 at grade B — 3 graded rows

What is known

Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.

Outcome	Grade	Effect size	Agreement
Mucus clearanceEstablished mucolytic	Evidence grade A	Moderate	high
Glutathione / oxidative markersReliable biomarker effect	Evidence grade B	Moderate	high
OCD / trichotillomania (adjunct)As add-on	Evidence grade B	Small	mixed

Mucus clearanceEvidence grade A
Established mucolytic
Moderatehigh
Glutathione / oxidative markersEvidence grade B
Reliable biomarker effect
Moderatehigh
OCD / trichotillomania (adjunct)Evidence grade B
As add-on
Smallmixed

What is uncertain

Read off the same rows as above. Nothing here is added that the entry does not itself record.

Studies disagree: OCD / trichotillomania (adjunct) (mixed agreement).

The evidence in words

What it is

NAC is the acetylated form of the amino acid cysteine, the rate-limiting building block of glutathione, the body's master antioxidant. It is a well-established drug (mucolytic and the standard acetaminophen-poisoning antidote) sold as a supplement in many markets.

How it works

By replenishing cysteine, NAC raises glutathione and buffers oxidative stress. It also modulates glutamate signaling, the basis for its psychiatric research, and breaks disulfide bonds in mucus, thinning it.

What the evidence shows

Strong as a mucolytic and lifesaving in acetaminophen overdose. As a supplement, the most interesting evidence is in psychiatry — modest benefits as an add-on in obsessive-compulsive and grooming disorders (trichotillomania), some substance-use and bipolar-depression signals — plus improvements in oxidative markers and possibly fertility. Effects outside the drug uses are modest and the trials are small.

How to use it

600–1,800 mg/day for general antioxidant/mucolytic use; psychiatric trials often used 2,400 mg/day. Clinical (poisoning) use is a hospital protocol.

Safety & interactions

Generally safe; GI upset is the main complaint, and its sulfur smell is off-putting. Theoretical additive effects with nitroglycerin and, at high doses, mild antiplatelet action.

Bottom line

A genuinely useful compound with real mechanisms: glutathione support, mucus-thinning, and modest psychiatric-adjunct evidence. 600–1,800 mg/day; the dramatic uses (overdose antidote) belong to medicine.

How it is used

As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.

General: 600–1,800 mg/day.
Psychiatric (trials): ~2,400 mg/day under care.

Entries that share this one's tags or conditions.

N-Acetylcysteine (NAC) for Glutathione / oxidative markersEvidence grade B — Reliable biomarker effectEvidence grade B
N-Acetylcysteine (NAC) for Mucus clearanceEvidence grade A — Established mucolyticEvidence grade A
N-Acetylcysteine (NAC) for OCD / trichotillomania (adjunct)Evidence grade B — As add-onEvidence grade B
N-Acetylcysteine (NAC): dosage and how to take it600–1,800 mg/day.Evidence grade B

Sources

This entry lists no references of its own.

Last revised Jul 10, 2026. A grade is this entry's reading of the evidence, not medical advice.