N-Acetylcysteine (NAC)

A precursor to glutathione, one of the body's main antioxidants

The best-evidenced ingredient in the respiratory-support category, with a long history as a prescription mucolytic before it showed up on supplement shelves.

What the evidence supports

Strong Mucus thinning Decades of use as a prescription mucolytic; well-documented mechanism, replicated across many small trials.

Moderate COPD exacerbation frequency Meta-analyses show fewer flare-ups with regular use, though effect size is modest and disease-management basics matter more.

Limited General antioxidant "detox" Marketing claim, not a studied endpoint — glutathione support doesn't translate to a measurable "detox" outcome.

Dose used in trials

600–1,200 mg

per day, often split into two doses, for respiratory outcomes.

Safety

Generally tolerated

GI upset and a distinctive sulphur smell are the common complaints.

Ask a doctor first if

You have asthma

Rare reports of bronchospasm with nebulised (not oral) NAC in sensitive individuals.

N-Acetylcysteine (NAC)

What the evidence supports

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