Acetylcysteine (NAC)

Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.

About Acetylcysteine

What it is

Acetylcysteine (N-acetylcysteine, NAC) replenishes glutathione, the body's main antioxidant, and breaks the bonds that make mucus thick. Given by drip, it is the antidote for paracetamol (acetaminophen) overdose; inhaled or by mouth, it loosens mucus in lung disease. It is also sold as a supplement. Brand names include Mucomyst and Acetadote.

How genes come into it

The gene studies on acetylcysteine come mainly from idiopathic pulmonary fibrosis: a re-analysis of the PANTHER trial suggested that people with a certain TOLLIP genotype (rs3750920) did better on NAC while others did not, a finding being tested in a newer trial. Studies have also looked at MUC5B and EPHX1. There is no CPIC or DPWG guideline.

What research found

Every published finding on gene variants and Acetylcysteine. Upload your DNA file to see which of these rows apply to you.

Rated evidence (1 rated variant)

PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.

TOLLIP rs3750920: Level 3. Efficacy: Pulmonary Fibrosis. 1.

Response (6 findings)

Studies of how well it worked in people carrying a variant.

EPHX1 EPHX1 poor metabolizer: EPHX1 poor metabolizer is associated with increased response to acetylcysteine in people with Pulmonary Disease, Chronic Obstructive as compared to genotype fast/normal (assigned as intermediate metabolizer and normal metabolizer phenotype) .

TOLLIP rs3750920: Genotype TT is associated with increased response to acetylcysteine in people with Pulmonary Fibrosis as compared to genotypes CC + CT.

MUC5B rs35705950: Genotype TT is not associated with response to acetylcysteine in people with Pulmonary Fibrosis as compared to genotypes GG + GT.

TOLLIP rs5743854: Genotype CC is not associated with response to acetylcysteine in people with Pulmonary Fibrosis as compared to genotypes CG + GG.

Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.

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Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.

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Content updated September 2026.

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