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Health Benefits, Uses, Side Effects & More


Updated August 02, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

N-acetylcysteine is an antioxidant sold in supplement form. Also referred to as N-Acetyl Cysteine (or NAC), N-acetyl-cysteine is converted by the body into an amino acid called cysteine. In turn, cysteine helps produce glutathione, an antioxidant that plays a key role in regulating many cellular functions and helps keep the immune system in check. Proponents claim that taking N-acetylcysteine supplements can protect against a wide range of health problems.

Health Benefits of N-Acetylcysteine

Here's a look at some key research findings:

1) Chronic Bronchitis

N-Acetylcysteine may help keep chronic bronchitis in check, according to a 2000 report in Clinical Therapeutics. Looking at data from eight clinical trials, the report's authors found that long-term use of N-acetylcysteine may help prevent acute flare-ups of chronic bronchitis and, in turn, lower healthcare costs.

See other remedies for bronchitis.

2) Diabetes

N-Acetylcysteine may aid in diabetes management, suggests a 2006 study from the Journal of Basic and Clinical Physiology and Pharmacology. Involving 32 patients with type 2 diabetes and 15 healthy controls, the study found that three months of treatment with N-acetylcysteine helped regulate glutathione levels in diabetes patients. The study's authors suggest that regulating glutathione levels may help protect against diabetic complications brought on by free radical-induced damage.

Find out about other natural treatments for diabetes.

3) Polycystic Ovary Syndrome

N-Acetylcysteine may help treat polycystic ovary syndrome (PCOS), according to a 2007 study in the journal Acta Obstetricia et Gynecologica Scandinavica. For one menstrual cycle, 573 PCOS patients were treated with clomiphene citrate (a drug commonly used to induce ovulation). Next, 470 of these patients took a combination of N-acetylcysteine and clomiphene citrate for another menstrual cycle. Study results revealed that ovulation rates improved significantly after the addition of N-acetylcysteine.

Learn about other natural remedies for PCOS.

4) Cystic Fibrosis

N-Acetylcysteine may have a slightly beneficial effect on lung function among people with cystic fibrosis, according to a 1999 report in Acta Paediatrica. Sizing up data from 23 studies, the report's authors concluded that there is not enough evidence to support the use of N-Acetylcysteine in the treatment of cystic fibrosis. However, the report's authors noted that long-term use of N-Acetylcysteine may lead to some improvement in lung function for cystic fibrosis patients.


In patients with stable, moderate-to-severe chronic obstructive pulmonary disease (COPD), N-acetylcysteine may help improve physical performance. For a 2009 study published in the journal Chest, 24 COPD patients took either N-acetylcysteine or a placebo> daily for six weeks. After taking a two-break (in order to eliminate N-acetylcysteine from the bodies of participants in the treatment group), the study participants were switched over to the alternate therapy for an additional six weeks. Study results indicated that N-acetylcysteine helped improve several markers of respiratory health, such as lung capacity and exercise endurance.


  • bronchitis
  • chronic obstructive pulmonary disorder (COPD)
  • cirrhosis
  • cystic fibrosis
  • high cholesterol
  • HIV and AIDS
  • Lou Gehrig's disease

Additionally, some proponents claim that N-acetylcysteine can help prevent cancer.

Side Effects

N-Acetylcysteine may trigger a number of side effects, including nausea, diarrhea and vomiting. What's more, N-acetylcysteine can increase your levels of homocysteine (an amino acid linked to heart disease). If you're taking N-acetylcysteine, it's important to get your homocysteine levels checked on a regular basis.

In addition, N-acetylcysteine may interact with several drugs (including certain blood pressure medications, medicines that suppress the immune system, cancer drugs and medications that treat chest pain).

Using N-Acetylcysteine

Although N-acetylcysteine may offer certain health benefits, self-treating a chronic health problem with N-acetylcysteine supplements may have serious health consequences. If you're considering taking N-acetylcysteine, talk to your doctor before starting your supplement regimen.


Badawy A, State O, Abdelgawad S. "N-Acetyl cysteine and clomiphene citrate for induction of ovulation in polycystic ovary syndrome: a cross-over trial." Acta Obstet Gynecol Scand. 2007;86(2):218-22.

Duijvestijn YC, Brand PL. "Systematic review of N-acetylcysteine in cystic fibrosis." Acta Paediatr. 1999 Jan;88(1):38-41.

Grandjean EM, Berthet P, Ruffmann R, Leuenberger P. "Efficacy of oral long-term N-acetylcysteine in chronic bronchopulmonary disease: a meta-analysis of published double-blind, placebo-controlled clinical trials." Clin Ther. 2000 Feb;22(2):209-21.

Memorial Sloan-Kettering Cancer Center. "N-Acetylcysteine". January 2011.

Ozkilic AC, Cengiz M, Ozaydin A, Cobanoglu A, Kanigur G. "The role of N-acetylcysteine treatment on anti-oxidative status in patients with type II diabetes mellitus." J Basic Clin Physiol Pharmacol. 2006;17(4):245-54.

Stav D, Raz M. "Effect of N-acetylcysteine on air trapping in COPD: a randomized placebo-controlled study." Chest. 2009 Aug;136(2):381-6.

University of Maryland Medical Center. "Cysteine". Last accessed July 2011.

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