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N-Acetyl Cysteine (NAC)
What is it? Overview Usage Side Effects and Warnings

N-Acetyl Cysteine (NAC) Usage

Written by FoundHealth.


Effect of N-Acetyl Cysteine (NAC) on Arrhythmias (Heart Rhythm Disturbances)

The exact effect of NAC on arrhythmias is not clear. When taken orally, NAC is thought to help the body make the important antioxidant enzyme glutathione.

Read more about Arrhythmias (Heart Rhythm Disturbances) and N-Acetyl Cysteine (NAC).

Therapeutic Uses

Significant but not entirely consistent evidence suggests that regular use of NAC is helpful for individuals with chronic bronchitis (a condition commonly associated with smoking and emphysema) in reducing frequency of acute flare-ups of the condition. 1 Regular use of NAC may help prevent influenza , possibly by stimulating immunity. 2 One substantial study found evidence that NAC may augment the effectiveness of clomiphene , a drug used for female infertility , in women with polycystic ovary syndrome . 3 Another study found NAC far less effective for this purpose than the drug metformin; however, it still could have provided some benefit.

Mixed evidence suggests that NAC may also enhance the effectiveness of the drug nitroglycerin , 4 5 6 7 8 used for the treatment of angina . However, severe headaches can develop as a side effect.

Note: Do not attempt to self-treat angina, acute respiratory distress syndrome, or acetaminophen poisoning! Medical supervision is absolutely essential because of the very real risk of death in these conditions.

NAC may be helpful in a life-threatening condition called acute respiratory distress syndrome. 9 Very high dosages of NAC are used in hospitals as a conventional treatment for acetaminophen poisoning.

According to some, but not all studies, NAC may be helpful for preventing complications that occur during cardiac surgery. 10 Some research has also suggested that NAC may be helpful for Sjogren’s syndrome 11 (a disease that causes dry eyes, among other symptoms), chronic blepharitis 12 (ongoing infections of the eyelid), severe liver disease, and reducing the side effects of the cancer chemotherapy drug ifosfamide. 13 14 15 16 Other evidence hints that NAC might help offset the carcinogenic effects of smoking and reduce colon cancer risk. 17 Weak evidence hints that NAC might reduce some side effects (specifically, cardiac toxicity and hair loss) caused by the cancer chemotherapy drug doxorubicin . 18 NAC has been proposed as supportive therapy for HIV . Despite some intriguing results, overall the evidence is inconsistent at best. 19 Several studies have suggested that NAC may be beneficial as an aid to treating various mental health disorders including schizophrenia , 20 cocaine-dependence, 21 and even pathological gambling. 22 In order to get more information from certain types of x-rays, radiologists often administer substances called contrast agents. Unfortunately, contrast agents can damage the kidney. It has been suggested that NAC can help protect the kidney from such damage; 23 however, the most recent and best-designed study failed to find benefit. 24 One double-blind trial failed to find NAC helpful for head and neck or lung cancer. 25 Studies have also failed to find NAC helpful for treating viral hepatitis , 26 preeclampsia , 27 or enhancing sports performance . 28


  1. 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. 22(2):209-21.
  2. De Flora S, Grassi C, Carati L. Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment. Eur Respir J. 10(7):1535-41.
  3. Rizk AY, Bedaiwy MA, Al-Inany HG. N-acetyl-cysteine is a novel adjuvant to clomiphene citrate in clomiphene citrate-resistant patients with polycystic ovary syndrome. Fertil Steril. 83(2):367-70.
  4. Pizzulli L, Hagendorff A, Zirbes M, Jung W, Lüderitz B. N-acetylcysteine attenuates nitroglycerin tolerance in patients with angina pectoris and normal left ventricular function. Am J Cardiol. 79(1):28-33.
  5. Ardissino D, Merlini PA, Savonitto S, et al. Effect of transdermal nitroglycerin or N-acetylcysteine, or both, in the long-term treatment of unstable angina pectoris. J Am Coll Cardiol. 1997;29:941-947.
  6. Iversen HK. N-acetylcysteine enhances nitroglycerin-induced headache and cranial arterial responses. Clin Pharmacol Ther. 52(2):125-33.
  7. Hogan JC, Lewis MJ, Henderson AH. Chronic administration of N-acetylcysteine fails to prevent nitrate tolerance in patients with stable angina pectoris. Br J Clin Pharmacol. 30(4):573-7.
  8. May DC, Popma JJ, Black WH, Schaefer S, Lee HR, Levine BD, Hillis LD. In vivo induction and reversal of nitroglycerin tolerance in human coronary arteries. N Engl J Med. 317(13):805-9.
  9. Bernard GR, Wheeler AP, Arons MM, et al. A trial of antioxidants N-acetylcysteine and procysteine in ARDS. The Antioxidant in ARDS Study Group. Chest. 1997;112:164-172.
  10. El-Hamamsy I, Stevens LM, Carrier M, Pellerin M, Bouchard D, Demers P, Cartier R, Page P, Perrault LP. Effect of intravenous N-acetylcysteine on outcomes after coronary artery bypass surgery: a randomized, double-blind, placebo-controlled clinical trial. J Thorac Cardiovasc Surg. 133(1):7-12.
  11. Walters MT, Rubin CE, Keightley SJ, Ward CD, Cawley MI. A double-blind, cross-over, study of oral N-acetylcysteine in Sjögren's syndrome. Scand J Rheumatol Suppl. 61():253-8.
  12. Yalçin E, Altin F, Cinhüseyinoglue F, Arslan MO. N-acetylcysteine in chronic blepharitis. Cornea. 21(2):164-8.
  13. Holoya PY, Duelge J, Hansen RM,. Prophylaxis of ifosfamide toxicity with oral acetylcysteine. Sem Oncol. 1983;10(suppl 1):66-71.
  14. Slavik M, Saiers JH. Phase I clinical study of acetylcysteine’s preventing ifosfamide-induced hematuria. Sem Oncol. 1983;10(suppl 1):62-65.
  15. Loehrer PJ, Williams SD, Einhorn LH. N-Acetylcysteine and ifosfamide in the treatment of unresectable pancreatic adenocarcinoma and refractory testicular cancer. Sem Oncol. 1983;10(suppl 1):72-75.
  16. Morgan LR, Donley PJ, Harrison EF. The control of ifosfamide induced hematuria with N-acetylcysteine. Proc Am Assoc Cancer Res. 1981;22:190.
  17. Estensen RD, Levy M, Klopp SJ, Galbraith AR, Mandel JS, Blomquist JA, Wattenberg LW. N-acetylcysteine suppression of the proliferative index in the colon of patients with previous adenomatous colonic polyps. Cancer Lett. 147(1-2):109-14.
  18. D'Agostini F, Bagnasco M, Giunciuglio D, Albini A, De Flora S. Inhibition by oral N-acetylcysteine of doxorubicin-induced clastogenicity and alopecia, and prevention of primary tumors and lung micrometastases in mice. Int J Oncol. 13(2):217-24.
  19. Akerlund B, Tynell E, Bratt G, et al. N-acetylcysteine treatment and the risk of toxic reactions to trimethoprim-sulphamethoxazole in primary Pneumocystis carinii prophylaxis in HIV-infected patients. J Infect. 1997;35:143-147.
  20. Berk M, Copolov D, Dean O, Lu K, Jeavons S, Schapkaitz I, Anderson-Hunt M, Judd F, Katz F, Katz P, Ording-Jespersen S, Little J, Conus P, Cuenod M, Do KQ, Bush AI. N-acetyl cysteine as a glutathione precursor for schizophrenia--a double-blind, randomized, placebo-controlled trial. Biol Psychiatry. 64(5):361-8.
  21. LaRowe SD, Myrick H, Hedden S, Mardikian P, Saladin M, McRae A, Brady K, Kalivas PW, Malcolm R. Is cocaine desire reduced by N-acetylcysteine? Am J Psychiatry. 164(7):1115-7.
  22. Grant JE, Kim SW, Odlaug BL. N-acetyl cysteine, a glutamate-modulating agent, in the treatment of pathological gambling: a pilot study. Biol Psychiatry. 62(6):652-7.
  23. May DC, Popma JJ, Black WH, Schaefer S, Lee HR, Levine BD, Hillis LD. In vivo induction and reversal of nitroglycerin tolerance in human coronary arteries. N Engl J Med. 317(13):805-9.
  24. Seyon RA, Jensen LA, Ferguson IA, Williams RG. Efficacy of N-acetylcysteine and hydration versus placebo and hydration in decreasing contrast-induced renal dysfunction in patients undergoing coronary angiography with or without concomitant percutaneous coronary intervention. Heart Lung. 36(3):195-204.
  25. van Zandwijk N, Dalesio O, Pastorino U, et al. EUROSCAN, a randomized trial of vitamin A and n-acetylcysteine in patients with head and neck cancer or lung cancer. J Natl Cancer Inst. 2000;92:977-986.
  26. Gunduz H, Karabay O, Tamer A, Ozaras R, Mert A, Tabak OF. N-acetyl cysteine therapy in acute viral hepatitis. World J Gastroenterol. 9(12):2698-700.
  27. Roes EM, Raijmakers MT, Boo TM, et al. Oral N-acetylcysteine administration does not stabilise the process of established severe preeclampsia. Eur J Obstet Gynecol Reprod Biol. 2005 Oct 19. [Epub ahead of print]
  28. Medved I, Brown MJ, Bjorksten AR, et al. N-acetylcysteine infusion alters blood redox status but not time to fatigue during intense exercise in humans. J Appl Physiol. 2003;94:1572-1582.


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