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N-acetyl cysteine (NAC) is a protein that helps the body intake antioxidants to slow damage to cells. It has been used to improve heart health and brain function. NAC has also been used to help the body fight illness. It can be taken as a pill or powder. It can also be injected into the bloodstream by a healthcare provider.
600 milligrams 2 to 6 times daily
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
It is likely safe to take N-acetyl cysteine in small doses for a short time, but nausea, vomiting, and diarrhea may happen. Not enough studies have been done to say whether it is safe to take for a long period. It is also not known whether it is safe to take by women who are breastfeeding.
Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.
A. Acute Liver Failure
A1. Hu J, Zhang Q, et a;. Efficacy and safety of acetylcysteine in "non-acetaminophen" acute liver failure: A meta-analysis of prospective clinical trials. Clin Res Hepatol Gastroenterol. 2015 Oct;39(5):594-599.
B. Bipolar Disorder
B1. . Zheng W, Zhang QE, et al. N-acetylcysteine for major mental disorders: a systematic review and meta-analysis of randomized controlled trials. Acta Psychiatr Scand. 2018 May;137(5):391-400.
C. Chronic Bronchitis
C1. Parr GD, Huitson A. Oral Fabrol (oral N-acetyl-cysteine) in chronic bronchitis. Br J Dis Chest. 1987;81(4):341-348.
C2. Cazzola M, Calzetta L, et al. Influence of N-acetylcysteine on chronic bronchitis or COPD exacerbations: a meta-analysis. Eur Respir Rev. 2015 Sep;24(137):451-461.
D. Chronic Kidney Disease
D1. Jun M, Venkataraman V, et al. Antioxidants for chronic kidney disease. Cochrane Database Syst Rev. 2012 Oct 17;10:CD008176.
E. Chronic Obstructive Pulmonary Disease
E1. Cazzola M, Calzetta L, et al. Influence of N-acetylcysteine on chronic bronchitis or COPD exacerbations: a meta-analysis. Eur Respir Rev. 2015 Sep;24(137):451-461.
E2. Fowdar K, Chen H, et al. The effect of N-acetylcysteine on exacerbations of chronic obstructive pulmonary disease: A meta-analysis and systematic review. Heart Lung. 2017 Mar - Apr;46(2):120-128.
F. Contrast-Induced Nephropathy
F1. Sun Z, Fu Q, et al. Intravenous N-acetylcysteine for prevention of contrast-induced nephropathy: a meta-analysis of randomized, controlled trials. PLoS One. 2013;8(1):e55124.
F2. Loomba RS, Shah PH, et al. Role of N-Acetylcysteine to Prevent Contrast-Induced Nephropathy: A Meta-analysis. Am J Ther. 2016 Jan-Feb;23(1):e172-83.
F3. Wang N, Qian P, et al. The effect of N-acetylcysteine on the incidence of contrast-induced kidney injury: A systematic review and trial sequential analysis. Int J Cardiol. 2016 Apr 15;209:319-327.
G. Depressive Symptoms
G1. Fernandes BS, Dean OM, et al. N-Acetylcysteine in depressive symptoms and functionality: a systematic review and meta-analysis. J Clin Psychiatry. 2016 Apr;77(4):e457-466.
H. H Pylori Infection
H1. Fontes LES, Martimbianco ALC, et al. N-acetylcysteine as an adjuvant therapy for Helicobacter pylori eradication. Cochrane Database Syst Rev. 2019 Feb 12;2:CD012357.
I. Heart Surgery Support
I1. Liu XH, Xu CY, et al. Efficacy of N-acetylcysteine in preventing atrial fibrillation after cardiac surgery: a meta-analysis of published randomized controlled trials. BMC Cardiovasc Disord. 2014 Apr 16;14:52.
I2. Ali-Hassan-Sayegh S, Mirhosseini SJ, et al. Antioxidant supplementations for prevention of atrial fibrillation after cardiac surgery: an updated comprehensive systematic review and meta-analysis of 23 randomized controlled trials. Interact Cardiovasc Thorac Surg. 2014 May;18(5):646-654.
I3. Rababa’h AM, Deo SV, et al. N-Acetly Cysteine Therapy Does Not Prevent Renal Failure in High-Risk Patients Undergoing Open-Heart Surgery. Heart Surg Forum. 2016;19(1):E16-22.
I4. Shafiei E, Bahtoei M, et al. Effects of N-acetyl cysteine and melatonin on early reperfusion injury in patients undergoing coronary artery bypass grafting: A randomized, open-labeled, placebo-controlled trial. Medicine (Baltimore). 2018;97(30):e11383.
J. Idiopathic Pulmonary Fibrosis
J1. Sun T, Liu J, et al. Efficacy of N-Acetylcysteine in Idiopathic Pulmonary Fibrosis: A Systematic Review and Meta-Analysis. Medicine (Baltimore). 2016 May;95(19):e3629.
J2. Rogliani P, Calzetta L, et al. Pirfenidone, nintedanib and N-acetylcysteine for the treatment of idiopathic pulmonary fibrosis: A systematic review and meta-analysis. Pulm Pharmacol Ther. 2016 Oct;40:95-103.
K. Major Depressive Disorder
K1. Berk M, Dean OM, et al. The efficacy of adjunctive N-acetylcysteine in major depressive disorder: a double-blind, randomized, placebo-controlled trial. J Clin Psychiatry. 2014;75(6):628-636.
K2. Zheng W, Zhang QE, et al. N-acetylcysteine for major mental disorders: a systematic review and meta-analysis of randomized controlled trials. Acta Psychiatr Scand. 2018 May;137(5):391-400.
L. Respiratory Tract Infections
L1. Chalumeau M, Duijvestijn YC. Acetylcysteine and carbocysteine for acute upper and lower respiratory tract infections in paediatric patients without chronic broncho-pulmonary disease. Cochrane Database Syst Rev. 2013 May 31;(5):CD003124.
M1. Sommer IE, van Westrhenen R, et al. Efficacy of anti-inflammatory agents to improve symptoms in patients with schizophrenia: an update. Schizophr Bull. 2014 Jan;40(1):181-191.
M2. Rapado-Castro M, Berk M, et al. Towards stage specific treatments: effects of duration of illness on therapeutic response to adjunctive treatment with N-acetyl cysteine in schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry. 2015; 57:69-75.
M3. Magalhães PV, Dean O, et al. Antioxidant treatments for schizophrenia. Cochrane Database Syst Rev. 2016 Feb 5;2:CD008919.
M4. Sepehrmanesh Z, Heidary M, et al. Therapeutic effects of adjunctive N-acetyl cysteine (NAC) on symptoms of chronic schizophrenia: A double-blind, randomized clinical trial. Prog Neuropsychopharmacol Biol Psychiatry. 2018;83:289-296.
M5. Breier A, Liffick E, et al. Effects of 12-month, double-blind N-acetyl cysteine on symptoms, cognition and brain morphology in early phase schizophrenia spectrum disorders. Schizophr Res. 2018;199:395-402.
M6. Zheng W, Zhang QE, et al. N-acetylcysteine for major mental disorders: a systematic review and meta-analysis of randomized controlled trials. Acta Psychiatr Scand. 2018 May;137(5):391-400.
N. Sepsis and Systemic Inflammatory Response
N1. Szakmany T, Hauser B, et al. N-acetylcysteine for sepsis and systemic inflammatory response in adults. Cochrane Database Syst Rev. 2012 Sep 12;(9):CD006616.
Last reviewed March 2020 by EBSCO NAT Review Board Eric Hurwitz, DC Last Updated: 6/29/2020