N-acetylcysteine (NAC)
Cochrane-supported mucolytic for COPD exacerbations; precursor to glutathione with emerging psychiatry signal.
Why
N-acetylcysteine (NAC) is a mucolytic precursor of glutathione, used clinically since the 1960s. The Cochrane review of NAC in chronic bronchitis and COPD found a modest but real reduction in exacerbation frequency at 1,200 mg/day. Separately, NAC is the standard antidote for paracetamol overdose. A newer body of psychiatry RCTs supports adjunctive use in OCD, trichotillomania, and bipolar depression, though psychiatric indications remain off-label.
How it works
Free thiol group disrupts mucin disulfide bridges (mucolytic effect). Provides cysteine for hepatic glutathione synthesis, the body's principal endogenous antioxidant. Modulates glutamate signalling via the cystine-glutamate antiporter, which underlies the psychiatric signal.
Expected onset · Mucolytic effect within days; exacerbation-reduction effects assessed over 6–12 months
How to take
Dosage
Mucolytic / COPD: 600 mg twice daily (1,200 mg/day total). Higher doses up to 2,400 mg/day used in psychiatric trials.
Timing
With or away from meals; effervescent forms have higher bioavailability
On the label
'N-acetyl-L-cysteine' or 'NAC' with stated milligrams. Effervescent forms (e.g. Fluimucil) have the most consistent absorption data.
Ideal for
Adults with chronic bronchitis or COPD with frequent exacerbations; people seeking glutathione precursor support.
Safety
Evidence
Cazzola 2015 Pulm Pharmacol Ther meta-analysis (13 RCTs, n>4,000): NAC 1,200 mg/day reduced COPD exacerbations vs placebo (rate ratio ~0.75). Cochrane 2019 SR on mucolytics in chronic bronchitis confirmed reduction in exacerbations and rescue antibiotic use. Psychiatric signal (OCD, trichotillomania, bipolar) is consistent but indications remain off-label.
- Cazzola et al., Pulm Pharmacol Ther 2015, N-acetylcysteine for COPD exacerbations: systematic review and meta-analysis
- Poole et al., Cochrane Database Syst Rev 2019, mucolytic agents versus placebo for chronic bronchitis or COPD
- Berk et al., Biol Psychiatry 2008, NAC as adjunctive treatment in bipolar depression (RCT)
Where to get it
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