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N-Acetyl Cysteine

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What other names is N-acetyl Cysteine known by?

Acetyl Cysteine, Acétyl Cystéine, Acetylcysteine, Acétylcystéine, Chlorhydrate de Cystéine, Cysteine, Cystéine, Cysteine Hydrochloride, Cystine, Hydrochlorure de Cystéine, L-Cysteine, L-Cystéine, L-Cysteine HCl, L-Cystéine HCl, NAC, N-Acetil Cisteína, N-Acetyl-B-Cysteine, N-Acétyl Cystéine, N-Acetyl-L-Cysteine, N-Acétyl-L-Cystéine, N-Acetylcysteine, N-Acétylcystéine.

What is N-acetyl Cysteine?

N-acetyl cysteine comes from the amino acid L-cysteine. Amino acids are the building blocks of proteins. N-acetyl cysteine has many uses as medicine.

People take N-acetyl cysteine by mouth to counteract acetaminophen (Tylenol) and carbon monoxide poisoning. It is also used for chest pain (unstable angina), bipolar disorder, genetic conditions known as lysosomal storage disorders, bile duct blockage in infants, amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease), Alzheimer's disease, allergic reactions to the anti-seizure drug phenytoin (Dilantin), an eye infection called keratoconjunctivitis, and influenza symptoms. It is also used for reducing levels of a type of blood fat called lipoprotein (a), homocysteine levels (a possible risk factor for heart disease), and the risk of heart attack and stroke in people with serious kidney disease.

N-acetyl cysteine is also taken by mouth for hepatitis, kidney disease, hearing loss, ulcerative colitis, polycystic ovary syndrome (PCOS), low blood pressure, lupus, certain conditions that occur after menopause, muscle damage due to exercise, schizophrenia, recovery after surgery, swelling of the pancreas (pancreatitis), cocaine dependence, altitude sickness, infection due to Helicobacter pylori bacteria, and for decreasing the risk for heart rhythm problems after surgery. It may also be used for genetic conditions known as adrenoleukodystrophy (ALD), erythropoietic protoporphyria (EPP), and hereditary hemorrhagic telangiectasia (HHT).

Some people use N-acetyl cysteine orally for long-term bronchitis, chronic obstructive pulmonary disease (COPD), cystic fibrosis, hay fever, human immunodeficiency virus (HIV), a lung condition called fibrosing alveolitis, autism, head and neck cancer, colorectal cancer, and lung cancer. It is also used for treating some forms of epilepsy, ear infections, complications of kidney dialysis, chronic fatigue syndrome (CFS), an autoimmune disorder called Sjogren's syndrome. It may be used for preventing sports injury complications, miscarriages, preterm labor, and liver damage due to alcohol use. Some people use N-acetyl cysteine to improve fertility and immunity to flu and H1N1 (swine) flu. It is also used for detoxifying heavy metals such as mercury, lead, and cadmium.

N-acetyl cysteine is also taken by mouth for protecting against environmental pollutants including carbon monoxide, chloroform, urethanes and certain herbicides; reducing toxicity of drugs used for cancer treatment; treating hangover symptoms; preventing kidney damage due to certain X-ray dyes; and treating compulsive hair pulling (trichotillomania).

N-acetyl cysteine is applied to the skin to treat a genetic condition known as lamellar ichthyosis. It is also applied inside the mouth to reduce dental plaque. Also, it is applied to the eye to improve dry eyes.

Healthcare providers give N-acetyl cysteine intravenously (by IV) for acetaminophen (Tylenol) overdose, acrylonitrile poisoning, amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease), kidney failure in the presence of liver disease (hepatorenal syndrome), pancreas swelling (pancreatitis), chest pain in combination with nitroglycerin, heart attack in combination with nitroglycerin and streptokinase, and for helping to prevent multi-organ failure leading to death. Intravenously, N-acetyl cysteine may also be used to improve recovery after surgery, decrease heart rhythm problems after surgery, treat a genetic condition known as adrenoleukodystrophy (ALD), improve exercise performance, treat acute respiratory distress syndrome (ARDS), improve lung function in patients with sepsis, and prevent kidney damage due to certain X-ray dyes. It is also used for pancreatitis, liver transplants, malaria, and cardiac bypass graft (CABG) surgery. It is also given by IV to reduce nitrate tolerance.

N-acetyl cysteine is sometimes used rectally for conditions known as meconium ileus and meconium ileus equivalent.

N-acetyl cysteine is sometimes inhaled (breathed into the lungs) or delivered through a tube in the throat to treat certain lung disorders such as asthma, pneumonia, chronic obstructive pulmonary disease (COPD), bronchitis, emphysema, cystic fibrosis, and others. It is also used to help prepare people for diagnostic lung tests and to help care for people with a tube in their windpipe.

Effective for...

  • Acetaminophen (Tylenol) poisoning. N-acetyl cysteine is effective in reducing the death rate and preventing the permanent harm caused by acetaminophen poisoning. For this use, N-acetyl cysteine given by mouth is as effective as N-acetyl cysteine given intravenously (by IV).
  • Collapse of part or all of a lung (atelectasis). N-acetyl cysteine helps treat collapsed lungs caused by mucus blockage.
  • Diagnostic lung tests. N-acetyl cysteine is helpful when used to prepare people for diagnostic lung tests.
  • Care of people with a tube in their windpipe (people who have undergone a tracheostomy). N-acetyl cysteine helps prevent crusting in people with a tube in their windpipe.

Possibly Effective for...

  • Chest pain (angina). Taking N-acetyl cysteine by mouth or injecting it intravenously (by IV) seems to improve chest pain when used with the drug nitroglycerin. Intravenous N-acetyl cysteine seems to help prevent nitroglycerin tolerance. Taking N-acetyl cysteine by mouth might also help prevent nitroglycerin tolerance, but results are conflicting.
  • Autism. Some research shows that taking N-acetyl cysteine by mouth improves irritability in children and adolescents with autism. But N-acetyl cysteine doesn't seem to improve other autism symptoms such as hyperactivity, social withdrawal, lethargy, and inappropriate speech.
  • Air passage swelling (bronchitis). Taking N-acetyl cysteine by mouth seems to reduce shortness of breath and coughing in people with air passage swelling due to mustard gas exposure. Also, taking N-acetyl cysteine by mouth for 3-6 months seems to prevent flare-ups in people with persistent air passage swelling. However, taking it for less time does not seem to be effective.
  • A lung disease called chronic obstructive pulmonary disease (COPD). Taking N-acetyl cysteine by mouth seems to decrease flare-ups by about 40% and improve sputum (phlegm) consistency in people with moderate to severe COPD. It seems to work best in people who are not already taking corticosteroids. However, it might increase the risk of blockage of the breathing tube.
  • Kidney problems caused by dyes used during some X-ray exams. Taking N-acetyl cysteine by mouth seems to help prevent kidney problems caused by dyes used during some X-ray exams in people with severely reduced kidney function (kidney insufficiency). It might help prevent these problems in people with moderately reduced kidney function. It does not seem to lower the risk of kidney problems caused by dyes used during X-ray exams in people with normal kidney function.
  • Serious kidney disease. Taking N-acetyl cysteine by mouth seems to help prevent problems, such as heart attack and stroke, in people with serious kidney disease. The risk reduction can be as much as 40%. However, N-acetyl cysteine doesn't reduce the overall risk of death or the risk of death from heart disease in these people.
  • Epilepsy seizures. Taking N-acetyl cysteine by mouth seems to help treat a certain type of epilepsy seizure.
  • A lung disease called fibrosing alveolitis. Taking N-acetyl cysteine by mouth seems to improve lung function in people with fibrosing alveolitis.
  • High levels of homocysteine. Taking N-acetyl cysteine by mouth seems to reduce homocysteine levels, a possible risk factor for heart disease.
  • High cholesterol. Taking N-acetyl cysteine by mouth seems to reduce levels of a blood fat called lipoprotein(a) in people with high levels of this blood fat.
  • Ifosfamide (Ifex) side effects. Taking N-acetyl cysteine by mouth seems to help prevent side effects of ifosfamide (Ifex), which is used for certain types of cancer. However the drug mesna (Mesnex) seems to work better than N-acetyl cysteine.
  • Flu. Taking N-acetyl cysteine by mouth seems to reduce flu symptoms.
  • Heart attack. . Injecting N-acetyl cysteine intravenously (by IV) seems to help maintain heart function in people having a heart attack when given with the drugs nitroglycerin and streptokinase.

Possibly Ineffective for...

  • Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Injecting N-acetyl cysteine intravenously (by IV) doesn't seem to improve ALS symptoms.
  • Breathing problems in premature infants. Giving N-acetyl cysteine through a hole in the windpipe does not seem to prevent breathing problems in premature infants.
  • Cystic fibrosis. Taking N-acetyl cysteine by mouth or inhaling it doesn't seem to improve lung function in people with cystic fibrosis. However, N-acetyl cysteine might reduce markers of swelling in people with cystic fibrosis when taken by mouth in high doses.
  • Doxorubicin side effects. Taking N-acetyl cysteine by mouth doesn't seem to prevent or treat heart damage caused by doxorubicin, a drug used to treat certain types of cancer.
  • A condition that causes sensitivity to light (erythropoietic protoporphyria, EPP). Taking N-acetyl cysteine by mouth doesn't seem to reduce light sensitivity in people with EPP.
  • Hepatitis. Taking N-acetyl cysteine by mouth doesn't seem to help treat viral hepatitis. It also doesn't seem to improve response to interferon therapy in people with hepatitis C. However, it might help prevent relapses in people with hepatitis C.
  • HIV/AIDS. Taking N-acetyl cysteine by mouth doesn't seem to improve immune function or reduce the amount of virus in the body in most people with HIV. However, it might improve immune function in people with HIV who have low levels of glutathione, a chemical in the body that is formed from N-acetyl cysteine.
  • Low blood pressure. Taking N-acetyl cysteine by mouth doesn't seem to reduce the risk of kidney failure in people with long-term low blood pressure.
  • Kidney disease. Taking N-acetyl cysteine doesn't seem to reduce kidney injury in people with long-term kidney disease.
  • Liver transplant. Injecting N-acetyl cysteine intravenously (by IV) during surgery to donate a liver and keeping the liver in a cold liquid containing N-acetyl cysteine before the liver transplant doesn't seem to prevent transplant rejection in liver transplant recipients.
  • Pancreas swelling (pancreatitis). Taking N-acetyl cysteine by mouth doesn't prevent pancreatitis in people undergoing a certain diagnostic procedure that can cause pancreas swelling. Also, injecting N-acetyl cysteine intravenously along with selenium and vitamin C doesn't seem to prevent pancreas dysfunction in people with serious pancreatitis.
  • Bone loss after menopause. Taking N-acetyl cysteine by mouth doesn't seem to prevent bone loss after menopause.
  • Recovery after surgery. Taking N-acetyl cysteine by mouth or injecting it intravenously (by IV) doesn't seem to reduce the risk of heart attack, stroke, kidney injury, or death after heart surgery. N-acetyl cysteine might help prevent abnormal heartbeats after heart surgery, but results are conflicting.

Likely Ineffective for...

  • Alzheimer's disease. Taking N-acetyl cysteine by mouth doesn't improve symptoms of Alzheimer's disease.
  • Head and neck cancer. Taking N-acetyl cysteine by mouth doesn't prevent new tumors or improve survival in people with head and neck cancer.
  • Lung cancer. Taking N-acetyl cysteine by mouth doesn't prevent new tumors or improve survival in people with lung cancer.
  • Treating organ failure. Injecting N-acetyl cysteine intravenously (by IV) might increase the risk of death in people with multiple organ failure.

Insufficient Evidence to Rate Effectiveness for...

  • A life-threatening lung condition (acute respiratory distress syndrome, ARDS). Some research shows that injecting N-acetyl cysteine intravenously (by IV) reduces the risk of death and improves some aspects of lung function in people with ARDS. However, conflicting research exists.
  • Adrenoleukodystrophy (ALD). Early research suggests that taking N-acetyl cysteine by mouth or injecting it intravenously (by IV) might improve survival and stabilize brain function in some people with ALD.
  • Altitude sickness. Early research suggests that taking N-acetyl cysteine doesn't prevent anorexia or other eating problems associated with altitude sickness.
  • Asthma. Early research suggests that inhaling a combination of N-acetyl cysteine plus isoproterenol improves lung function and decreases sputum (phlegm) thickness in people with asthma.
  • Bipolar disorder. Early research suggests that taking N-acetyl cysteine by mouth seems to help reduce depression symptoms in people with bipolar disorder. But it does not seem to help with symptoms of mania.
  • Heart bypass surgery. Early research suggests that N-acetyl cysteine does not prevent death or improve outcomes after surgery in patients undergoing heart bypass surgery.
  • Cocaine dependence. Some early research shows that taking N-acetyl cysteine by mouth reduces the desire to use cocaine in people who are cocaine dependent. But conflicting results exist.
  • Colon cancer. Taking N-acetyl cysteine by mouth may reduce the likelihood of colon and rectal cancer in patients with a history of adenomatous colon polyps.
  • Dental plaque. Early research suggests that using a mouthwash containing 10% N-acetyl cysteine may reduce plaque.
  • Dry eye syndrome. Early research suggests that using a tear solution containing 20% acetyl cysteine improves some but not all symptoms of dry eye syndrome.
  • Muscle damage due to exercise. Early research suggests that taking N-acetyl cysteine by mouth does not help prevent muscle damage after exercise.
  • Exercise performance. Some early research suggests that injecting N-acetyl cysteine intravenously (by IV) before and during exercise increases the time until fatigue in trained athletes. Other early research shows that taking N-acetyl cysteine by mouth might improve performance of well-trained triathletes.
  • Hearing loss. Early research suggests that taking N-acetyl cysteine by mouth decreases the chance of hearing loss in people who work in loud conditions, such as factory workers.
  • Helicobacter pylori (H. pylori) infection. Some research suggests that taking N-acetyl cysteine by mouth along with usual treatment for H. pylori infection increases the number of people who experience complete infection elimination. But other early research suggests that taking N-acetyl cysteine along with curcumin, bovine lactoferrin, and the drug pantoprazole does not help eliminate H. pylori infection.
  • Kidney failure in people with liver disease (hepatorenal syndrome). Early research suggests that injecting N-acetyl cysteine intravenously (by IV) might improve kidney function in people with hepatorenal syndrome.
  • A blood disorder called hereditary hemorrhagic telangiectasia (HHT). Early research suggests that taking N-acetyl cysteine decreases the number and severity of nosebleeds during the day in people with HHT. But it doesn't seem to reduce the number of nighttime nosebleeds.
  • Infertility. Taking N-acetyl cysteine by mouth seems to improve sperm concentration but not sperm movement in infertile men. In women with fertility problems who are taking the fertility drug clomiphene citrate, taking N-acetyl cysteine by mouth does not seem to improve pregnancy rate or miscarriage rate.
  • A skin disease called lamellar ichthyosis. Applying N-acetyl cysteine to the skin might help treat lamellar ichthyosis.
  • Malaria. Early research suggests that injecting N-acetyl cysteine intravenously (by IV) along with the antimalarial drug artesunate does not reduce symptoms or prevent death in people with severe malaria.
  • Miscarriage. Early research suggests that taking N-acetyl cysteine by mouth along with folic acid helps prevent early miscarriages in women with a history of multiple early miscarriages compared to taking only folic acid.
  • Tolerance to nitrate. Early research suggests that injecting N-acetyl cysteine intravenously (by IV) seems to help prevent tolerance to nitrate. Oral N-acetyl cysteine might help prevent nitrate tolerance, but results are conflicting.
  • Nerve problems caused by oxaliplatin. Early research suggests that taking N-acetyl cysteine by mouth reduces the risk of nerve damage in people receiving oxaliplatin, a drug used to treat certain types of cancer.
  • Polycystic ovarian syndrome (PCOS). Research shows that taking N-acetyl cysteine by mouth increases the odds of ovulation, getting pregnant, and having a live birth in women with PCOS. It seems to work best in women who are resistant to the fertility drug clomiphene citrate. But metformin seems to work better than N-acetyl cysteine. N-acetyl cysteine doesn't seem to improve irregular menstruation or decrease acne or male-pattern hair growth in women with PCOS.
  • Preterm labor. Taking N-acetyl cysteine by mouth along with a certain steroid hormone beginning at 16-18 weeks pregnancy and continuing until labor seems to help prevent preterm labor better than taking the steroid hormone alone. However, taking N-acetyl cysteine by mouth beginning at 25-33 weeks pregnancy and continuing until labor does not seem to improve preterm delivery rates in women with severe high blood pressure during pregnancy (pre-eclampsia) or those with HELLP syndrome.
  • Schizophrenia. Taking N-acetyl cysteine by mouth for 6 months seems to reduce symptoms in people with schizophrenia. But taking N-acetyl cysteine for only 2 months doesn't seem to work.
  • Septic shock. Injecting N-acetyl cysteine intravenously (by IV) might help improve the ability to breathe in people with septic shock. But it doesn't seem to help prevent death due to septic shock.
  • An autoimmune disorder called Sjogren's syndrome. Taking N-acetyl cysteine by mouth might reduce eye soreness and irritation, bad breath, and daytime thirst in people with this condition. But it doesn't seem to reduce eye dryness.
  • Lupus. Early research shows that taking N-acetyl cysteine by mouth reduces disease activity and tiredness in people with lupus.
  • Hair pulling. Taking N-acetyl cysteine by mouth seems to decrease hair pulling in adults by up to 40%. But it doesn't seem to reduce hair pulling in children.
  • Ulcerative colitis. Early research suggests that taking N-acetyl cysteine by mouth doesn't help prevent flare-ups in people with ulcerative colitis who are taking the anti-inflammatory drug mesalamine.
  • Allergic reactions to phenytoin (Dilantin).
  • Carbon monoxide poisoning.
  • Chronic fatigue syndrome (CFS).
  • Ear infections.
  • Hay fever.
  • Preventing alcoholic liver damage.
  • Protecting against environmental pollutants.
  • Removing heavy metals such as mercury, lead, and cadmium from the body.
  • Other conditions.
More evidence is needed to rate the effectiveness of N-acetyl cysteine for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).


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