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What is N-acetylcysteine?

N-acetylcysteine is a nonessential amino acid derivative, which can be produced in your body from the amino acid cysteine, so you do not need to get it from foods to be healthy [1].

N-Acetylcysteine Functions in the Human Body

N-acetylcysteine is [1]:

  • A nonproteinogenic amino acid, which is not regularly incorporated into proteins
  • A precursor of the antioxidant glutathione
  • A mucolytic–it makes mucus more liquid

N-Acetylcysteine Supplements

Nonprescription (over-the-counter):

  • N-acetylcysteine capsules and creams

By prescription:

  • Oral n-acetylcysteine (capsules)
  • N-acetylcysteine intravenous injections
  • N-acetylcysteine for inhalation

N-acetylcysteine Health Benefits

N-acetylcysteine supplements are EFFECTIVE in:

  • Acetaminophen (paracetamol) poisoning (as an oral drug or intravenous injection) [2,6,14]

N-acetylcysteine supplements are POSSIBLY EFFECTIVE in [2]:

  • Treatment of collapsed lungs–atelectasis [12,13,14]
  • Prevention of crusting after tracheostomy [2]
  • Lowering homocysteine levels (a possible risk factor for heart disease) [25,26,27,28,29]

There is CONFLICTING EVIDENCE about the effectiveness of N-acetylcysteine in the prevention of worsening of chronic bronchitis (chronic obstructive pulmonary disease) [2,14,20,21,22,33].

N-acetylcysteine are POSSIBLY INEFFECTIVE [2] in the prevention or treatment of Alzheimer’s disease, amyotrophic lateral sclerosis (ALS, Lou Gehrig’s disease) [9], anxiety [9], bone loss in women after menopause, chronic kidney disease, head and neck tumors or lung cancer and viral hepatitis, HIV/AIDS, low blood pressure, pancreatitis, sensitivity to light in erythropoietic protoporphyria and side effects of doxorubicin (used for treating cancer), or in recovery after surgery.

There is INSUFFICIENT EVIDENCE [2] about N-acetylcysteine effectiveness in the prevention or treatment of acute respiratory distress syndrome (ARDS), alcoholic liver damage, altitude sickness, allergic reactions to phenytoin, Alzheimer’s disease [9], angina pectoris [16], asthma, attention deficit-hyperactive disorder (ADHD) [9], autism [9], bipolar disorder [9], carbon monoxide poisoning [14], cataracts, cerebral adrenoleukodystrophy, chronic fatigue syndrome (CFS), nicotine, cocaine or cannabis [8,9] or gambling addiction [9], colon cancer, cystic fibrosis [7], dental plaques, depression [9], diabetes mellitus type 2, dry eyes, ear infections, fertility, hair pulling and nail biting in psychiatric patients [3,9], hay fever, Helicobacter pylori infection of the stomach, hereditary hemorrhagic telangiectasia, HIV/AIDS, idiopathic pulmonary fibrosis [33], influenza (flu) [31,32,33], kidney problems with contrast dyes used during X-ray imaging [4,5,33], lamellar ichthyosis, liver cirrhosis, macular degeneration, malaria, mucus softening in various lung conditions (COPD) [10,11], multiple sclerosis [9], neuropathy [9], obsessive compulsive disorder (OCD) [9,23], polycystic ovarian syndrome (PCOS) [24], Parkinson’s disease [9], rheumatoid arthritis, schizophrenia [9], seizures (epilepsy) [9], septic shock, Sjögren’s syndrome, stroke [9] or ulcerative colitis, or in increasing tolerance to nitrates (drugs to treat ischemic heart disease) [15,17,18,19], boosting immunity, stimulating hair growth, improving exercise performance, increasing HDL cholesterol, relieving side effects of ifosfamide (a drug used for treating cancer) [30], improving memory or removing mercury, lead and cadmium from the body.

N-acetylcysteine Safety: Side Effects, Toxicity

Prescribed N-acetylcysteine is LIKELY SAFE for most adults [2].

Side effects may include nausea, vomiting, diarrhea or constipation or, rarely, rashes, fever, headache, drowsiness, low blood pressure, and liver problems [2]. Allergy to N-acetylcysteine is possible.

Who should not take N-acetylcysteine?

Pregnant and breastfeeding women and individuals with asthma and cystinuria should avoid N-acetylcysteine [2]. Children should not take N-acetylcysteine without prescription.

N-acetylcysteine-Drug Interactions

N-acetylcysteine supplements may [2]:

  • Increase side effects of nitroglycerin (headache), increase the effect of ACE inhibitors (medications for high blood pressure), such as enalapril and captopril, and immunosuppressors, such as azathioprine and prednisone.

  1. N-acetyl-L-cysteine  PubChem
  2. N-acetyl cysteine uses, side effects  WebMD
  3. Sansone RA et al, 2011, Getting a Knack for NAC  PubMed Central
  4. De Rosa SC et al, 2000, N-acetylcysteine replenishes glutathione in HIV infection  PubMed
  5. Pannu N, 2004, Systematic review of the impact of N-acetylcysteine on contrast nephropathy  PubMed
  6. Green JL et al, 2013, Oral and Intravenous Acetylcysteine for Treatment of Acetaminophen Toxicity: A Systematic Review and Meta-analysis  PubMed Central
  7. Duijvestijn YC et al, 1999, Systematic review of N-acetylcysteine in cystic fibrosis  PubMed
  8. Asevedo E et al, 2014, Systematic review of N-acetylcysteine in the treatment of addictions  PubMed
  9. Deepmala et al, 2015, Clinical trials of N-acetylcysteine in psychiatry and neurology: A systematic review  ScienceDirect
  10. Shen Y et al, 2014, Effect of high/low dose N-acetylcysteine on chronic obstructive pulmonary disease: a systematic review and meta-analysis  PubMed
  11. Sadowska AM et al, 2006, Role of N-acetylcysteine in the management of COPD  PubMed Central
  12. Mirhosseini JH et al, 2013, N-acetylcysteine instead of theophylline in patients with COPD who are candidates for elective off-pump CABG surgery: Is it possible in cardiovascular surgery unit?  PubMed Central
  13. Jepsen S et al, 1989, Peroral N-acetylcysteine as prophylaxis against bronchopulmonary complications of pulmonary surgery  PubMed
  14. N-Acetylcysteine – Medical Countermeasures Database  CHEMM
  15. Parker JO et al, 1987, Nitrate tolerance: the lack of effect of N-acetylcysteine  PubMed
  16. Chirkov YY et al, 1996, N-Acetylcysteine potentiates nitroglycerin-induced reversal of platelet aggregation  PubMed
  17. Hogan JC et al, 1990, Chronic administration of N-acetylcysteine fails to prevent nitrate tolerance in patients with stable angina pectoris PubMed
  18. Ardissino D et al, 1997, Effect of Transdermal Nitroglycerin or N-Acetylcysteine, or Both, in the Long-Term Treatment of Unstable Angina Pectoris  ScienceDirect
  19. Maxwell SRJ et al, 1992, An update on nitrate tolerance: can it be avoided?  PubMed Central
  20. Stey C et al, 2000, The effect of oral N-acetylcysteine in chronic bronchitis: a quantitative systematic review  PubMed
  21. Dekhuijzen PNR et al, 2006, The role for N-acetylcysteine in the management of COPD  PubMed Central
  22. Aitio ML, 2006, N-acetylcysteine – passe-partout or much ado about nothing?  PubMed Central
  23. Oliver G et al, 2015, N-acetyl cysteine in the treatment of obsessive compulsive and related disorders: a systematic review  PubMed
  24. Thaker D et al, 2015, -Acetylcysteine for Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials  PubMed Central
  25. Bostom AG et al, 1996, Lack of effect of oral N-acetylcysteine on the acute dialysis-related lowering of total plasma homocysteine in hemodialysis patients  PubMed
  26. Thaha M et al, 2006, Intravenous N-acetylcysteine during haemodialysis reduces the plasma concentration of homocysteine in patients with end-stage renal disease  PubMed
  27. Miner SE et al, 2002, N-acetylcysteine neither lowers plasma homocysteine concentrations nor improves brachial artery endothelial function in cardiac transplant recipients  PubMed
  28. Friedman AN et al, 2003, The effect of N-acetylcysteine on plasma total homocysteine levels in hemodialysis: a randomized, controlled study  PubMed
  29. Yilmaz H et al, 2007, Effects of folic acid and N-acetylcysteine on plasma homocysteine levels and endothelial function in patients with coronary artery disease  PubMed
  30. Chen N et al, 2007, Prevention of ifosfamide nephrotoxicity by N-acetylcysteine: clinical pharmacokinetic considerations  PubMed
  31. De Flora S et al, 1997, Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment  PubMed
  32. The Flu, the Common Cold, and Complementary Health Approaches  National Center of Complementary and Integrative Health
  33. Millea PJ et al, 2009, N-Acetylcysteine: Multiple Clinical Applications  American Family Physician

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