NAC (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.

How does it work?

N-acetyl cysteine treats acetaminophen (Tylenol) poisoning by binding the poisonous forms of acetaminophen that are formed in the liver. It is also an antioxidant, so it may play a role in preventing cancer.

Acetaminophen (Tylenol) poisoning.
Collapse of part or all of a lung (atelectasis).
Diagnostic lung tests.
Care of people with a tube in their windpipe (people who have undergone a tracheostomy).
Chest pain (angina).
Autism.
Air passage swelling (bronchitis). disease (COPD).
Serious kidney disease.
Nerve problems caused by oxaliplatin.
Epilepsy seizures.
Bipolar disorder
High levels of homocysteine.
High cholesterol.
Ifosfamide (Ifex) side effects.
Flu.
Heart attack.

Adults

By Mouth:

For acetaminophen (Tylenol) overdose: 140 mg/kg of N-acetyl cysteine at first, followed by 70 mg/kg every 4 hours for 3 days or until acetaminophen is no longer detected in the blood.

For chest pain that is not relieved by rest (unstable angina): 600 mg of N-acetyl cysteine three times daily with a nitroglycerin patch.

For preventing sudden worsening of chronic bronchitis: Doses of 200 mg twice daily, 200 mg three times daily, 300 mg slow-release twice daily, and 600 mg controlled-release twice daily have been used for up to 6 months. Doses up to 1.5 grams per day for up to 4 months have also been used.

For treating chronic obstructive pulmonary disease (COPD): 400-1200 mg of N-acetyl cysteine daily in divided doses, in addition to standard care, has been used for up to 6 months.

For preventing kidney damage due to X-ray dye: 400 to 600 mg of N-acetyl cysteine twice daily on the day before and on the day of iopromide administration, with IV saline (0.45%) 1 mL/kg body weight per hour for 12 hours before and 12 hours after iopromide administration. Also, a starting dose of 1200 mg of N-acetyl cysteine, followed by 1200 mg twice daily thereafter for 48 hours after dye has also been used.

For treating a lung condition called fibrosing alveolitis that makes breathing difficult: 600 mg of N-acetyl cysteine three times daily for 12 weeks.

For preventing damage to the bladder due to treatment with a cancer drug called ifosfamide: 1-3 grams of N-acetyl cysteine every 6 hours beginning one hour before ifosfamide treatment and continuing for up to 5 days after treatment.

For reducing levels of homocysteine in the blood: 600-1200 mg of N-acetyl cysteine daily.

For epilepsy: 4-6 grams daily.

For reducing flu symptoms: 600 mg twice daily for up to 30 months.

For reducing the risk of heart attacks and strokes in patients with end-stage kidney disease: 600 mg twice daily.

For high cholesterol: 1.2 grams daily for 6 weeks or 2 grams daily for 4 weeks followed by 4 grams daily for another 4 weeks.

By Inhalation:

For collapse of part or all of a lung (atelectasis): 3-5 mL of 20% solution or 6-10 mL of 10% solution administered using a nebulizer 3-4 times per day. The solution may also be administered through a tracheostomy at a dose of 1-2 mL of 10% or 20% solution every 1-4 hours. The solution may also be administered through a tracheal catheter at a dose of 1-2 mL of 20% solution or 2-4 mL of 10% solution every 1-4 hours.

For diagnostic lung tests: 1-2 mL of 20% solution of 2-4% of 10% solution administered via intratracheal instillation 2-3 times prior to the diagnostic test.

For treating chronic obstructive pulmonary disease (COPD): 20% solution administered via a nebulizer for at least 4 days.

For care of people with a tube in their windpipe (people who have undergone a tracheostomy): 1-2 mL of 10-20% solution administered via intratracheal instillation.


Children

By Mouth:

For acetaminophen (Tylenol) overdose: 140 mg/kg initially followed by 70 mg/kg every 4 hours for 72 hours or until acetaminophen is no longer detected in the body.

For autism: 900 mg daily for 4 weeks followed by 900 mg twice daily for 4 weeks followed by 900 mg three times daily for 4 weeks. Taking 1200 mg daily with the drug risperidone for 8 weeks has also been used.

By Inhalation:

For collapse of part or all of a lung (atelectasis): 3-5 mL of 20% solution or 6-10 mL of 10% solution administered using a nebulizer three to four times per day. The solution may also be administered through a tracheostomy at a dose of 1-2 mL of 10% or 20% solution every 1-4 hours. The solution may also be administered through a tracheal catheter at a dose of 1-2 mL of 20% solution or 2-4 mL of 10% solution every 1-4 hours.

For diagnostic lung tests: 1-2 mL of 20% solution or 2-4 mL of 10% solution administered via intratracheal instillation 2-3 times prior to the diagnostic test.

For care of people with a tube in their windpipe (people who have undergone a tracheostomy): 1-2 mL of 10% or 20% solution administered via intratracheal instillation.

N-acetyl cysteine is SAFE for most adults, when used as a prescription medication. It can cause nausea, vomiting, and diarrhea or constipation. Rarely, it can cause rashes, fever, headache, drowsiness, low blood pressure, and liver problems.

When inhaled (breathed into the lungs), it can also cause swelling in the mouth, runny nose, drowsiness, clamminess, and chest tightness.

N-acetyl cysteine has an unpleasant odor that may make it hard to take.

Pregnancy or breast-feeding: N-acetyl cysteine is SAFE when taken by mouth, delivered through a hole in the windpipe, or inhaled by women who are pregnant. N-acetyl cysteine crosses the placenta, but there is no evidence that it harms the unborn child or mother. But N-acetyl cysteine should only be used in pregnant women when medically needed.

There is not enough reliable information about the safety of taking N-acetyl cysteine if you are breast-feeding. Stay on the safe side and avoid use.

Allergy: Don't use N-acetyl cysteine if you are allergic to acetyl cysteine.

Asthma: There is a concern that N-acetyl cysteine might cause bronchospasm in people with asthma if inhaled or taken by mouth or through a tube in the windpipe. If you take N-acetyl cysteine and have asthma, you should be monitored by your healthcare provider.

Bleeding disorder. N-acetyl cysteine might slow blood clotting. There is concern that N-acetyl cysteine might increase the risk of bruising and bleeding in people with bleeding disorders.

Surgery. N-acetyl cysteine might slow blood clotting. This might increase the risk of bleeding during and after surgery. Stop taking N-acetyl cysteine at least 2 weeks before a scheduled surgery.