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FAQ: Acetylcysteine

Why is this medication being recommended?

Acetylcysteine is an antioxidant that can reduce the inflammation in your lungs. Inflammation is the precursor to fibrosis (scarring) in the lungs. By reducing inflammation, we hope acetylcysteine will prevent the formation of lung fibrosis and allow the inflamed lung to return to normal.

Acetylcysteine is sold over the counter at most pharmacies and health food stores. It's unclear whether there's any benefit in using one formulation over another, but we've had success with the following formulas:

  • Jarrow Formulas NAC Sustain 600 mg tablets
    Take one tablet three times daily
    Call (310) 204-6936 or go to You will find a Store Locator in the left hand column of the Jarrow home page. Type in your zip code and radius, and you will get a list of stores selling Jarrow products. You can also buy it from the following sources: or 1-800-381-0759 or 1-866-328-1171 or 1-800-633-1106

  • PharmaNAC 900 mg effervescent tablets
    Take one tablet dissolved in water twice daily
    Call 1-888-550-5350 or go to Click on 'USA,' then click the PharmaNAC box at the bottom.

What special precautions should I follow?

Before taking acetylcysteine, tell your doctor and pharmacist if you're allergic to acetylcysteine or any other medications.

What side effects can this medication cause?

Acetylcysteine may cause side effects. Tell your doctor if any of the following symptoms are severe or do not go away: upset stomach, vomiting, rash or fever.

What monitoring will I need?

Routine monitoring is not required while you are taking acetylcysteine.


Reviewed by health care specialists at UCSF Medical Center.

This information is for educational purposes only and is not intended to replace the advice of your doctor or health care provider. We encourage you to discuss with your doctor any questions or concerns you may have.