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N-Acetyl Cysteine

What is n-acetyl cysteine? Why do we need it?

N-acetyl cysteine is an altered form of cysteine, an amino acid found in most types of foods and synthesized in the body. The body derives cysteine from n-acetyl cysteine.

N-acetyl cysteine helps the body break down mucus. Research conducted in the 1980s showed that people taking supplements of n-acetyl cysteine were less likely to get recurring cases of chronic bronchitis. It also helps the body synthesize glutathione, and protects the body from acetimanophen toxicity and iopromide poisoning. In addition n-acetyl cysteine supplements may reduce the risk of colon cancer in people who have recurrent colon polyps.

How much n-acetyl cysteine should I take?

Because n-acetyl cysteine is not normally needed by healthy people, daily recommended allowances have yet to be established. However, most of the research on n-acetyl cysteine has used dosages ranging from 250 milligrams to 1,250 milligrams per day.

What forms of n-acetyl cysteine are available?

N-acetyl cysteine is not a normal part of the human diet. However, cysteine - the amino acid from which n-acetyl cysteine is derived, is found in most high-protein foods. Some stores sell n-acetyl supplements, which can be found as tablets, powders and liquid capsules.

What can happen if I take too much n-acetyl cysteine? Are there any interactions I should be aware of? What precautions should I take?

One study published in the early 1980s found that people taking oral doses of n-acetyl cysteine experienced side-effects such as nausea, vomiting and headaches, but these symptoms have not been reported consistently in other studies. Another study published in 1992 found that large amounts of cysteine could cause damage to nerve cells and increased oxidative stress. In addition, n-acetyl cysteine may increase urinary zinc excretion; as a result, people taking n-acetyl cysteine for long periods of time should also increase their intake of zinc and copper.

N-acetyl cysteine interact may interact with other drugs and medications, including acetaminophen, AZT, interferon, and nitroglycerine. Make sure to consult with a licensed health care provider about all possible drug interactions with n-acetyl cysteine, and make sure to consult with a licensed health care provider before taking n-acetyl cysteine or any other dietary supplement or herbal remedy.


  • Grandjean EM, Berthet P, Ruffmann R, Leuenberger P. Efficacy of oral long-term N-acetyl cysteine in chronic bronchopulmonary disease: A meta-analysis of published double-blind, placebo-controlled clinical trials. Clin Ther 2000;22:209-21.
  • Kleinveld HA, Demacker PNM, Stalenhoef AFH. Failure of N-acetyl cysteine to reduce low-density lipoprotein oxidizability in healthy subjects. Eur J Clin Pharmacol 1992;43:639-42.
  • Multicenter Study Group. Long-term oral acetylcysteine in chronic bronchitis. A double-blind controlled study. Eur J Respir Dis 1980;61:111:93-108.
  • Shyu KG, Cheng JJ, Kuan P. Acetyl cysteine protects against acute renal damage in patients with abnormal renal function undergoing a coronary procedure. J Am Coll Cardiol 2002;40:1383-8.
  • Tattersall AB, Bridgman KM, Huitson A. Acetylcysteine (Fabrol) in chronic bronchitis-a study in general practice. J Int Med Res 1983;11:279-84.
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