How Do You Spell Versatile? Try N-A-C

N-acetylcysteine (NAC) is one of the most versatile of all dietary supplements, and is used in both conventional and complementary medicine. It is a potent antioxidant and a precursor to glutathione, the most powerful antioxidant made by the body. NAC is also a rich source of sulfur, a mineral needed to make some vitamins, hormones, and tissue.

NAC is used in conventional medicine for two primary reasons. It is used in every hospital to treat acetaminophen, or Tylenol®, overdose. Large amounts of acetaminophen deplete the liver’s store of glutathione, which is needed to detoxify hazardous chemicals. Without glutathione, the liver itself will quickly break down. NAC restores glutathione levels and normal liver function. Hospitals also often use NAC to break up mucous in the lungs and to improve breathing. While it has been used for years in conventional medicine, over the past several years it has become popular as a supplement.

Infection Fighter

I first read about NAC in 1997 when Italian doctors showed that NAC supplements suppressed flu symptoms in seniors. In the study, Silvio De Flora, MD, of the University of Genoa, and his colleagues asked 262 patients to take either 600 mg of NAC or placebos twice daily for six months over the wintertime cold-and-flu season. Few of the subjects taking NAC developed flu symptoms, even though blood tests confirmed they were infected. When subjects did develop symptoms, they were generally mild among people taking NAC, compared with those who were taking placebos.1 NAC controlled the respiratory symptoms of the flu and, through its conversion to glutathione, boosted the body’s ability to fight infection.

Other studies support the broad benefits of NAC in fighting infections. A Stanford University study of AIDS patients found that those patients taking several grams of NAC daily lived significantly longer than those who declined to take the supplement.2 Meanwhile, a study in Sweden showed that people taking NAC took 38 percent fewer sick days because of chronic bronchitis, compared with those who took placebos.3

Diverse Health Benefits

In addition to being a potent infection-fighter, NAC provides an array of other physical and mental health benefits.

  • Polycystic Ovary Syndrome. An estimated 10 percent of women of childbearing age have polycystic ovary syndrome (PCOS). The condition is often diagnosed while trying to identify a cause for infertility. PCOS is characterized by enlarged cystic ovaries, high levels of male hormones, obesity, elevated insulin levels, and pre-diabetic insulin resistance. Doctors at the Trakya University School of Medicine, Turkey, treated 20 women with PCOS, giving them 600 mg of NAC daily for four weeks. The women benefited from a 58 percent decrease in blood testosterone levels, as well as about a one-third decrease in insulin resistance.4 An earlier study, published by Italian researchers, also found that NAC reduced insulin levels and insulin resistance.
  • Detoxification. Just as NAC restores liver function after acetaminophen overdose, it also helps the body eliminate toxic pesticides and mercury. Recently, doctors in Turkey described their use of NAC in the treatment of a patient with endosulfan overdose. Endosulfan is a neurotoxic organochlorine pesticide used on farms in the United States and other countries. The patient was hospitalized with convulsions and elevated liver enzymes, a sign of liver damage. After several days of high-dose NAC treatment, he was released in good health from the hospital.5 Another study, conducted at the University of Rochester School of Medicine, New York, showed that supplemental NAC accelerated the excretion of mercury from various organs in laboratory rats. The researchers said that “NAC may be an excellent agent for enhancing methylmercury elimination in exposed individuals.”6
  • Addiction Disorders. There’s growing evidence that NAC may help reduce obsessive-compulsive disorder (OCD) and addiction disorders. The theory is that NAC increases brain levels of glutamate, a neurotransmitter that the body converts to gamma- aminobutyric acid (GABA). In a recent report, Jon E. Grant, MD, of the University of Minnesota School of Medicine, described three patients with various pathological behaviors, including nail biting, hair pulling, or skin picking. Their OCD behavior ceased after taking 1,200 to 2,400 mg of NAC daily. Grant has also reported that daily NAC supplements can reduce obsessive-compulsive gambling within a matter of weeks.7
    Several studies have shown that NAC, taken at 600 mg four times daily, can reduce the desire for cocaine, as well as psychological responses to cocaine-related paraphernalia. A study completed at the Medical University of South Carolina found NAC to be effective in treating cocaine addiction. “For the 16 subjects who completed the study, nine subjects terminated use of cocaine completely during the medication phase, five subjects substantially decreased their use, and two demonstrated no change in cocaine use,” wrote Pascale N. Mardikian, MD, one of the lead researchers.8 9 It is believed that NAC helps regulate levels of serotonin and dopamine in the brain.
  • Kidney Booster. People undergoing angioplasty, a heart procedure, have a high risk of developing kidney complications. That’s because doctors inject a mildly radioactive dye, which generates free radicals and constricts blood vessels in the kidneys. The New England Journal of Medicine reported that a combination of oral and intravenous NAC significantly reduced the risk of kidney complications after angioplasty. Other research also points to NAC’s ability to heal kidney damage.

NAC is a standout supplement for preventing the cold and flu, maintaining normal liver detoxifying capabilities, reversing at least some of the symptoms of PCOS, treating addiction disorders, and protecting the kidneys. It is beneficial in so many ways that I sometimes describe NAC as a nutritional “tonic.” Given its benefits, NAC is certainly worth including in any dietary supplement regimen. Aside from having a sulfur-like odor, NAC supplements are safe in high doses. Take 500 to 600 mg daily, doubling the dose during the cold and flu season. On the first day of cold or flu symptoms, you can increase the dose up to 4,000 mg daily to reduce symptoms. (After the first day, any cold or flu remedy will be less effective because viral concentrations have increased.) For PCOS, take 600 mg three times daily. For obsessive-compulsive disorder, take 600 mg daily, increasing dose to 3,000 mg daily over six weeks. To prevent kidney damage, work with your doctor, but a medical journal reported that 1,200 mg intravenously, followed by 1,200 mg orally, twice daily was helpful.


  1. De Flora S, Grassi C, and Carati L. Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity withlong-term N-acetylcysteine treatment. European Respiratory Journal, 1997;10:1535-1541.
  2. Herzenberg LA, De Rosa SC, Dubs JG, et al. Glutathione deficiency is associated with impaired survival in HIV diseae. Proceedings of the National Academy of Sciences of the USA, 1997;94:1967-72.
  3. Rasmussen JB, Glennow C. Reduction in days of illness after long-term treatment with N-acetylcysteinecontrolled-release tablets in patients with chronic bronchitis. European Respiratory Journal, 1988;1:351-355.
  4. Kilic-Okman T, Kucuk M. N-acetylcysteine treatment for polycystic ovary syndrome. International Journal of Gynecology & Obstetrics, 2004;85:296-297.
  5. Demircan A, Çalidag E, Özsaraç M, et al. Acute intoxication by endosulfan: any role of n-acetylcysteine therapy? Turkish Journal of Medical Sciences, 2008;38:365-367.
  6. Aremu DA, Madejczyk MS, Ballatori N. N-acetylcysteine as a potential antidote and biomonitoring agent of methylmercury exposure. Environmental Health Perspectives, 2008; 116:26-31
  7. Grant JE, Kim SW, Odlaug BL. N-acetylcysteine, a glutamate-modulating agent, in the treatment of pathological gambling: a pilot study. Biological Psychiatry, 2007;62:652-657.
  8. Mardikian PN, LsRowe SD, Hedden S, et al. An open-label trial of N-acetylcysteine for the treatment of cocaine dependence: a pilot study. Progress in Neuro Psychopharmacology & Biological Psychiatry, 2007;31:389-394.
  9. Grant JE, Kim SW, Odlaug BL. N-acetylcysteine, a glutamate-modulating agent, in the treatment of pathological gambling: a pilot study. Biological Psychiatry, 2007;62:652-657.