N-acetyl cysteine (NAC) comes from the amino acid L-cysteine. Amino acids are building blocks of proteins. NAC has many uses and is an FDA approved drug.
N-acetyl cysteine is an antioxidant that might play a role in preventing cancer. As a drug, it's used by healthcare providers to treat acetaminophen (Tylenol) poisoning. It works by binding the poisonous forms of acetaminophen that are formed in the liver.
People commonly use N-acetyl cysteine for cough and other lung conditions. It is also used for flu, dry eye, and many other conditions, but there is no good scientific evidence to support many of these uses. There is also no good evidence to support using N-acetyl cysteine for COVID-19.
Although many dietary supplement products contain N-acetyl cysteine, the US FDA states that it's illegal for dietary supplements to contain N-acetyl cysteine since it's technically an approved drug. Prescription N-acetyl cysteine products are available under the guidance of a healthcare provider.
- Acetaminophen poisoning.  Oral and intravenous N-acetyl cysteine, as prescription drug products, are effective for treating acetaminophen poisoning.
Login for details - Atelectasis.  When inhaled, N-acetyl cysteine is effective for treating atelectasis.
Login for details - Bronchial diagnostic studies.  When inhaled, N-acetyl cysteine is effective for bronchial diagnostic study preparation.
Login for details - Tracheostomy care.  When inhaled and used as adjunct therapy, N-acetyl cysteine is effective for preventing endotracheal crusting in patients with a tracheostomy.
Login for details
- Angina.  Oral or intravenous N-acetyl cysteine may reduce nitroglycerin tolerance in patients with angina. However, some studies suggest that N-acetyl cysteine might increase the risk for severe headaches and hypotension when used with intravenous or transdermal nitroglycerin.
Login for details - Autism spectrum disorder.  Oral N-acetyl cysteine may improve irritability, but not other symptoms, associated with autism spectrum disorder.
Login for details - Bronchitis.  Via inhalation, N-acetyl cysteine is FDA-approved for managing acute episodes of bronchitis. Oral N-acetyl cysteine may help to reduce the occurrence of acute exacerbations of chronic bronchitis when used for 3-36 months.
Login for details - Chronic obstructive pulmonary disease (COPD).  Taking N-acetyl cysteine orally seems to decrease the exacerbation rate and improve symptoms in patients with moderate to severe COPD, particularly those who are not taking inhaled corticosteroids. Also, taking N-acetyl cysteine along with standard therapy appears to improve recovery in patients hospitalized due to an acute exacerbation.
Login for details - Contrast induced nephropathy.  Oral or intravenous administration of N-acetyl cysteine seems to prevent contrast induced nephropathy in patients with kidney dysfunction. However, it is not beneficial in those with normal kidney function or diabetes.
Login for details - Hyperhomocysteinemia.  Oral N-acetyl cysteine seems to reduce homocysteine levels.
Login for details - Hyperlipidemia.  Oral N-acetyl cysteine seems to reduce lipoprotein(a) levels.
Login for details - Ifosfamide (Ifex) toxicity.  Oral N-acetyl cysteine may be beneficial for reducing ifosfamide toxicity, although it does not appear to be as effective as mesna.
Login for details - Influenza.  Oral N-acetyl cysteine may reduce the risk for symptomatic influenza.
Login for details - Kidney failure.  Oral N-acetyl cysteine may reduce the risk for cardiovascular events in patients with kidney failure.
Login for details - Myocardial infarction (MI).  Intravenous N-acetyl cysteine, along with standard therapy, seems to improve outcomes in patients with MI. Oral N-acetyl cysteine has not been evaluated for this use.
Login for details
- Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease).  Subcutaneous administration of N-acetyl cysteine does not seem to improve survival or disease progression in patients with ALS.
Login for details - Anthracycline cardiotoxicity.  Oral N-acetyl cysteine does not seem to prevent or treat doxorubicin-induced cardiac toxicity.
Login for details - Bronchopulmonary dysplasia.  Intratracheal N-acetyl cysteine does not seem to prevent bronchopulmonary dysplasia in premature infants.
Login for details - Cannabis use disorder.  Oral N-acetyl cysteine does not seem to improve abstinence rates in patients with cannabis use disorder.
Login for details - Cystic fibrosis.  Oral or inhaled N-acetyl cysteine does not seem to improve lung function in patients with cystic fibrosis.
Login for details - Erythropoietic protoporphyria (EPP).  Oral N-acetyl cysteine does not seem to improve photosensitivity in patients with EPP.
Login for details - Helicobacter pylori.  Adding oral N-acetyl cysteine to conventional Helicobacter pylori (H. pylori) eradication regimens does not seem to increase eradication rates.
Login for details - Hepatitis.  Oral N-acetyl cysteine does not appear to improve treatment response in patients with hepatitis. However, when taken with interferon, it might lengthen the time to relapse.
Login for details - HIV/AIDS.  Oral N-acetyl cysteine does not seem to increase CD4+ cell count in patients with HIV.
Login for details - Hypotension.  Oral N-acetyl cysteine does not seem to improve renal outcomes in patients with prolonged hypotension.
Login for details - Infertility.  Oral N-acetyl cysteine does not seem to improve fertility in females with unexplained infertility.
Login for details - Liver transplant.  Intravenous N-acetyl cysteine during liver donor operation does not seem to improve liver transplant outcomes. Oral N-acetyl cysteine has not been evaluated for this use.
Login for details - Pancreatitis.  Oral N-acetyl cysteine does not seem to prevent pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP). Additionally, intravenous N-acetyl cysteine does not seem to reduce the risk of organ dysfunction in patients being treated for severe acute pancreatitis.
Login for details - Postoperative recovery.  Oral or intravenous N-acetyl cysteine does not seem to improve survival, prevent complications, or reduce length of hospital stay in patients undergoing cardiac or liver surgery.
Login for details
- Head and neck cancer.  Oral N-acetyl cysteine does not seem to reduce mortality, improve event-free survival, or prevent additional tumors in patients with head and neck cancer.
Login for details - Lung cancer.  Oral N-acetyl cysteine does not seem to reduce mortality, improve event-free survival, or prevent additional tumors in patients with lung cancer.
Login for details - Multisystem organ failure.  Administering intravenous N-acetyl cysteine might increase the risk of mortality due to multisystem organ failure. Oral N-acetyl cysteine has not been evaluated for this use.
Login for details
- Acute respiratory distress syndrome (ARDS).  Research on the use of intravenous N-acetyl cysteine in patients with ARDS is conflicting. Oral N-acetyl cysteine has not been evaluated for this purpose.
Login for details - Adrenoleukodystrophy (ALD).  It is unclear if oral or intravenous N-acetyl cysteine is beneficial in patients with ALD.
Login for details - Alcohol-related liver disease. Login for details
- Allergic rhinitis (hay fever). Login for details
- Altitude sickness.  It is unclear if oral N-acetyl cysteine can treat or prevent altitude sickness.
Login for details - Alzheimer disease.  It is unclear if oral N-acetyl cysteine is beneficial for this condition.
Login for details - Aminoglycoside ototoxicity.  Small clinical studies suggest that oral N-acetyl cysteine may modestly reduce the risk of ototoxicity caused by aminoglycoside therapy.
Login for details - Asthma.  It is unclear if inhaling N-acetyl cysteine is beneficial in patients with asthma.
Login for details - Athletic performance.  It is unclear if oral N-acetyl cysteine can improve athletic performance.
Login for details - Biliary disorders.  It is unclear if intravenous N-acetyl cysteine is beneficial in patients with biliary disorders. Oral N-acetyl cysteine has not been evaluated for this use.
Login for details - Bipolar disorder.  The effects of oral N-acetyl cysteine in patients with bipolar disorder are conflicting. Oral N-acetyl cysteine might reduce symptoms of depression and increase remission rates, but it does not appear to be beneficial for reducing symptoms of mania or for maintaining remission.
Login for details - Bronchiectasis.  Oral N-acetyl cysteine has been evaluated in patients with bronchiectasis, with promising results.
Login for details - Canker sores.  It is unclear if rinsing the mouth with N-acetyl cysteine solution is beneficial in patients with canker sores.
Login for details - Chemotherapy-induced hepatotoxicity.  It is unclear if intravenous N-acetyl cysteine is beneficial in patients with chemotherapy-induced hepatotoxicity. Oral N-acetyl cysteine has not been evaluated for this use.
Login for details - Chemotherapy-induced peripheral neuropathy.  Small clinical studies suggest that oral N-acetyl cysteine may reduce the risk for peripheral neuropathy in patients receiving oxaliplatin.
Login for details - Chronic fatigue syndrome (CFS). Login for details
- Chronic kidney disease (CKD).  Oral N-acetyl cysteine does not seem to improve kidney function in patients with CKD or reduce the risk of kidney injury or other complications after cardiac surgery in patients with CKD. However, intravenous N-acetyl cysteine might offer some benefit in patients with CKD undergoing cardiac surgery.
Login for details - Coronary artery bypass graft (CABG) surgery.  It is unclear if oral N-acetyl cysteine is beneficial in patients undergoing CABG surgery.
Login for details - Cocaine dependence.  It is unclear if oral N-acetyl cysteine is effective for reducing cravings or withdrawal symptoms in people trying to stop cocaine use.
Login for details - Colorectal cancer.  It is unclear if oral N-acetyl cysteine is effective for preventing colorectal cancer.
Login for details - Coronavirus disease 2019 (COVID-19).  Small clinical trials suggest that intravenous N-acetyl cysteine is not beneficial in patients at risk for respiratory failure from severe COVID-19. It is unknown if oral use is beneficial.
Login for details - Dental plaque.  It is unclear if mouthwash solutions containing N-acetyl cysteine can reduce dental plaque; higher concentrations may be more effective than lower concentrations.
Login for details - Dry eye.  Small clinical studies suggest that eye drops containing N-acetyl cysteine, with or without chitosan, might improve objective measures of dry eye.
Login for details - Endometriosis.  Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details - Exercise-induced muscle damage.  It is unclear if oral N-acetyl cysteine is effective for preventing or treating exercise-induced muscle damage.
Login for details - Gingivitis.  It is unclear if mouthwash containing N-acetyl cysteine is effective for the prevention or treatment of gingivitis.
Login for details - Hangover. Login for details
- Hearing loss.  It is unclear if oral N-acetyl cysteine is effective for preventing or treating hearing loss.
Login for details - Hepatorenal syndrome.  It is unclear if intravenous N-acetyl cysteine is beneficial in patients with hepatorenal syndrome. Oral N-acetyl cysteine has not been evaluated for this use.
Login for details - Hereditary hemorrhagic telangiectasia (HHT).  It is unclear if oral N-acetyl cysteine is beneficial in patients with HHT.
Login for details - Idiopathic interstitial pneumonia.  It is unclear if oral or inhaled N-acetyl cysteine is beneficial for the management of various forms of interstitial pneumonia.
Login for details - Lead toxicity. Login for details
- Malaria.  It is unclear if intravenous N-acetyl cysteine is beneficial as an adjunct in treating malaria. Oral N-acetyl cysteine has not been evaluated for this use.
Login for details - Male infertility.  It is unclear of oral N-acetyl cysteine is beneficial for male infertility.
Login for details - Mercury toxicity. Login for details
- Miscarriage.  Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its benefit when used alone is unclear.
Login for details - Multiple sclerosis (MS).  It is unclear if oral and intravenous N-acetyl cysteine are beneficial in patients with MS.
Login for details - Nitrate tolerance.  Intravenous N-acetyl cysteine seems to reduce the development of nitrate tolerance. Oral N-acetyl cysteine has shown mixed results for this use.
Login for details - Nonalcoholic steatohepatitis (NASH).  It is unclear if oral N-acetyl cysteine is beneficial in patients with NASH.
Login for details - Obsessive-compulsive disorder (OCD).  Oral N-acetyl cysteine might improve some symptoms of OCD when used with fluvoxamine in adults. Its effects when used as monotherapy in children and adults are unclear.
Login for details - Otitis media. Login for details
- Polycystic ovary syndrome (PCOS).  Oral N-acetyl cysteine might improve pregnancy-related outcomes in PCOS, although it appears to be less effective than metformin. Evidence on its benefits for other symptoms of PCOS is conflicting.
Login for details - Post-traumatic stress disorder (PTSD).  It is unclear if oral N-acetyl cysteine is beneficial in veterans with PTSD.
Login for details - Postmenopausal conditions.  It is unclear if oral N-acetyl cysteine is beneficial for preventing postmenopausal bone loss.
Login for details - Preterm labor.  It is unclear if oral N-acetyl cysteine is beneficial for reducing the risk for preterm labor.
Login for details - Radiation-induced sialadenitis.  It is unclear if mouthwash containing N-acetyl cysteine is beneficial for reducing dry mouth during chemoradiotherapy.
Login for details - Schizophrenia.  Oral N-acetyl cysteine seems to improve negative symptoms of schizophrenia. The benefits of N-acetyl cysteine on positive symptoms of schizophrenia are less clear.
Login for details - Sepsis.  Small clinical studies suggest that intravenous N-acetyl cysteine may improve respiratory function and tissue oxygenation, but not mortality, in patients with septic shock.
Login for details - Sjogren syndrome.  Small clinical studies suggest that oral N-acetyl cysteine may improve ocular and oral manifestations of this condition.
Login for details - Systemic lupus erythematosus (SLE).  It is unclear if oral N-acetyl cysteine is beneficial in patients with SLE.
Login for details - Tourette syndrome.  It is unclear if oral N-acetyl cysteine is beneficial in patients with this condition.
Login for details - Trichotillomania (hair pulling).  Oral N-acetyl cysteine might offer some benefit to adults, but not children, with trichotillomania.
Login for details - Ulcerative colitis.  It is unclear if oral N-acetyl cysteine is beneficial in patients with ulcerative colitis.
Login for details - Urinary tract infections (UTIs).  Oral N-acetyl cysteine has only been evaluated in combination with other ingredients; its effect when used alone is unclear.
Login for details
When taken by mouth: N-acetyl cysteine is likely safe for most adults. N-acetyl cysteine is an FDA-approved prescription drug. It can cause side effects such as dry mouth, nausea, vomiting, and diarrhea. It has an unpleasant odor that some people find hard to tolerate.
When inhaled: N-acetyl cysteine is likely safe for most adults, when used as a prescription medication. It can cause swelling in the mouth, runny nose, drowsiness, clamminess, and chest tightness.
Special Precautions & Warnings:
Pregnancy: N-acetyl cysteine is possibly safe when taken by mouth or inhaled during pregnancy. N-acetyl cysteine crosses the placenta, but there is no evidence that it harms the unborn child. But N-acetyl cysteine should only be used when medically needed.Breast-feeding: There isn't enough reliable information to know if N-acetyl cysteine is safe to use during breast-feeding. Stay on the safe side and avoid use.
Children: N-acetyl cysteine is likely safe when taken by mouth in doses of 900-2700 mg daily for up to 12 weeks.
Allergy: Don't use N-acetyl cysteine if you are allergic to acetyl cysteine.
Asthma: N-acetyl cysteine might cause bronchospasm in people with asthma if inhaled or taken by mouth. 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. 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.
Activated charcoal
Interaction Rating=Moderate Be cautious with this combination.
Activated charcoal is sometimes used to prevent poisoning in people who take too much acetaminophen and other medications. Activated charcoal can bind up these medications in the stomach and prevent them from being absorbed by the body. Taking N-acetyl cysteine at the same time as activated charcoal might decrease how well it works for preventing poisoning.
Nitroglycerin
Interaction Rating=Major Do not take this combination.
Nitroglycerin can dilate blood vessels and increase blood flow. Taking N-acetyl cysteine seems to increase the effects of nitroglycerin. This could cause increased chance of side effects including headache, dizziness, and lightheadedness.
Herbs and supplements that might lower blood pressure: N-acetyl cysteine might lower blood pressure. Taking it with other supplements that have the same effect might cause blood pressure to drop too much. Examples of supplements with this effect include andrographis, casein peptides, L-arginine, niacin, and stinging nettle.
Herbs and supplements that might slow blood clotting: N-acetyl cysteine might slow blood clotting and increase the risk of bleeding. Taking it with other supplements with similar effects might increase the risk of bleeding in some people. Examples of supplements with this effect include garlic, ginger, ginkgo, nattokinase, and Panax ginseng.
There are no known interactions with foods.
N-acetyl cysteine is an FDA approved prescription drug. It can be taken in various ways, including by mouth, by IV, and by inhalation. It is most commonly taken by mouth in doses of 600-1200 mg daily. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.
N-acetyl cysteine is also available in many dietary supplements. But according to the FDA, using N-acetyl cysteine in supplements is illegal because it is an approved drug. Supplement products should not be used in place of prescription products.
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.
Natural Medicines disclaims any responsibility related to medical consequences of using any medical product. Effort is made to ensure that the information contained in this monograph is accurate at the time it was published. Consumers and medical professionals who consult this monograph are cautioned that any medical or product related decision is the sole responsibility of the consumer and/or the health care professional. A legal License Agreement sets limitations on downloading, storing, or printing content from this Database. Except for any possible exceptions written into your License Agreement, no reproduction of this monograph or any content from this Database is permitted without written permission from the publisher. Unlawful to download, store, or distribute content from this site.
For the latest comprehensive data on this and every other natural medicine, health professionals should consult the Professional Version of the Natural Medicines. It is fully referenced and updated daily.
© Copyright 1995-2021. Therapeutic Research Faculty, publishers of Natural Medicines, Prescriber's Letter, and Pharmacist's Letter. All rights reserved.