NAC is a form of the amino acid cysteine. It thins mucus and helps the body make glutathione. In much of Europe it is sold as a medicine for coughs with mucus.
Calculator Official intake Study doses Best form Safety Sources
NAC is not a nutrient, so there is no official daily intake. Only study doses are shown.
These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.
1,200 mg a day
PANTHEON (China) gave people with COPD 600 mg twice a day for a year: flare-ups were fewer, most clearly in moderate disease. A meta-analysis found NAC lowered exacerbations, with high doses (1200 mg a day) needed in confirmed COPD.
No best form
Why: Plain NAC is the form in all the trials. Effervescent tablets (common in the EU) and capsules both work.
Not found as NAC in food; cysteine comes from protein (meat, eggs, legumes).
Should not be taken with nitroglycerin (can cause severe headache and low blood pressure). Ask before combining with activated charcoal or some cough medicines.
Can cause nausea and a sulfur smell. People with asthma should be cautious. NAC for paracetamol (acetaminophen) overdose is a hospital treatment, never self-treatment.
Pregnant, breastfeeding, on medication, or managing a health condition? Check with a doctor or pharmacist before starting a supplement.
Values checked: November 12, 2026.
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