Health Benefits of N-Acetylcysteine

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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.


In alternative medicine, N-acetylcysteine is said to help with a variety of conditions.

  • 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.

So far, scientific support for the benefits of N-acetylcysteine is lacking. Here's a look at some key research findings:

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 health care costs.


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.

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.

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.

Long-term use of N-acetylcysteine may lead to some improvement in lung function for cystic fibrosis patients, the study author's noted.


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.

N-acetylcysteine helped improve several markers of respiratory health, such as lung capacity and exercise endurance.


Little is known about the safety of long-term use of N-acetylcysteine.

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.

Some adverse events have been reported in animal studies (typically at higher doses), such as pulmonary hypertension and seizures. 

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).

Supplements haven't been tested for safety and due to the fact that dietary supplements are largely unregulated, the content of some products may differ from what is specified on the product label.

Also keep in mind that the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications has not been established.

Using It for Health

Due to a lack of supporting research, it's too soon to recommend N-acetylcysteine for any condition. 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.

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Article Sources

  • 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"