N-Acetyl-L-Cysteine: Benefits, Dosage, Contraindications
Other name(s)
Cysteine Hydrochloride
Scientific name(s)
NAC
Family or group:
Amino Acids
Indications
Rating methodology
EFSA approval.
Bronchitis ✪✪✪✪✪
The oral intake of N-acetyl cysteine at doses of 1200-1500 mg/day for 4 months appears to reduce cough and improve lung capacity in patients with sulfur mustard-induced bronchitis. Additionally, taking oral N-acetyl cysteine at 400 to 1200 mg per day for 3 to 6 months appears to reduce the risk of acute exacerbations of chronic bronchitis. However, shorter duration intake does not seem to have a beneficial effect on chronic bronchitis.
Posologie
Oral
400 - 1200 mg
6 - months
Efficacy of oral long-term N-acetylcysteine in chronic bronchopulmonary disease: a meta-analysis of published double-blind, placebo-controlled clinical trials.
N-acetylcysteine improves the clinical conditions of mustard gas-exposed patients with normal pulmonary function test.
The effect of oral N-acetylcysteine in chronic bronchitis: a quantitative systematic review.
Autism ✪✪✪✪✪
Some clinical research shows that taking N-acetyl cysteine at 900 mg per day for 4 weeks, then 900 mg twice a day for 4 weeks, and then 900 mg three times a day for 4 weeks improves irritability symptoms in children with autism spectrum disorders. Additional clinical research shows that taking N-acetyl cysteine at 1200 mg per day in combination with risperidone (an antipsychotic) for 8 weeks is more effective than risperidone alone for reducing irritability in children and adolescents with autism spectrum disorders. Although N-acetyl cysteine seems slightly effective in reducing irritability, it does not appear to improve other symptoms associated with autism spectrum disorders.
Posologie
Oral
900 - 2700 mg
3 - months
A randomized controlled pilot trial of oral N-acetylcysteine in children with autism.
A randomised, double blind, placebo-controlled trial of a fixed dose of N-acetyl cysteine in children with autistic disorder.
Chronic Obstructive Pulmonary Disease ✪✪✪✪✪
N-acetyl cysteine solution for inhalation is FDA approved for the management of chronic bronchopulmonary diseases, such as chronic obstructive pulmonary disease (COPD). A meta-analysis of 12 clinical studies shows that N-acetyl cysteine, administered for at least 6 months, decreases the number of patients suffering from at least one exacerbation of chronic obstructive pulmonary disease (COPD) by 15% compared to placebo; however, it is not associated with a reduction in the rate of exacerbation of COPD or an improvement in lung function measures. Other smaller studies have shown a higher rate of improvement from 23% to 40%, with the greatest efficacy observed in patients not already taking inhaled corticosteroids. N-acetyl cysteine has been used at doses of 400 to 1200 mg per day in divided doses for 4 to 6 months. It has also been used in nebulized form, on two alternating days for at least four days.
Posologie
Oral
400 - 1200 mg
6 - months
N-acetylcysteine reduces the exacerbation rate in patients with moderate to severe COPD.
Global Initiative for Chronic Obstructive Lung Disease (GOLD). GOLD 2017 global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease, 2017 report
N-acetylcysteine and exacerbations of chronic obstructive pulmonary disease.
Prevention of acute exacerbations of COPD: American College of Chest Physicians and Canadian Thoracic Society Guideline.
Trichotillomania ✪✪✪✪✪
Preliminary evidence suggests a reduction of 31 to 45% in hair-pulling symptoms in people with trichotillomania when supplemented with 1,200 to 2,400 mg of N-acetylcysteine for 12 weeks. However, in children, taking N-acetylcysteine at doses up to 2400 mg per day for 12 weeks does not appear to improve hair-pulling compared to placebo.
Posologie
Orally
1200 - 2400 mg
12 - weeks
Detoxification ✪✪✪✪✪
Supplementation with 200 to 800 mg of N-acetylcysteine for 3 months among workers exposed to industrial levels of lead can reduce lead accumulation in red blood cells and resultant oxidative sequelae, as well as improve glutathione levels in red blood cells.
Posologie
Orally
200 - 800 mg
3 - months
Smoking cessation ✪✪✪✪✪
A double-blind study demonstrated that after approximately two weeks of supplementation with 2400 mg of N-acetylcysteine, cigarette consumption seems to have voluntarily decreased by about 25%.
Posologie
Orally
2400 mg
2 - weeks
Acne ✪✪✪✪✪
Taking 1200 mg of N-acetylcysteine for at least two months resulted in a significant reduction in the total number of lesions.
Posologie
Orally
1200 - 1200 mg
2 - months
Obsessive Compulsive Disorder ✪✪✪✪✪
Preliminary clinical research shows that taking 1000 mg of N-acetylcysteine twice daily with 200 mg/day of fluvoxamine (an antidepressant medication) for 10 weeks moderately reduces general symptoms of obsessive-compulsive disorder and obsession symptoms compared to fluvoxamine with placebo. However, adding N-acetylcysteine is not associated with improvement in compulsion symptoms nor a statistically significant increase in partial or complete responses compared to fluvoxamine alone.
Posologie
Orally
2000 mg
10 - weeks
Substance Abuse ✪✪✪✪✪
Some preliminary clinical evidence suggests that taking 600 mg of N-acetylcysteine twice daily for two days reduces the desire to consume cocaine compared to placebo among cocaine-dependent individuals. However, other preliminary clinical evidence suggests that oral intake of 600 mg N-acetylcysteine twice a day for 2 days does not reduce cravings or withdrawal symptoms compared to placebo in hospitalized patients for cocaine dependence. On the other hand, a supplementation of 2,400 mg seems to reduce symptoms of marijuana dependence, although the symptom reduction is not too significant.
Posologie
Orally
1200 - 2400 mg
2 - days
Endometriosis ✪✪✪✪✪
Patients started treatment with the combination: N-acetyl cysteine, alpha lipoic acid, and bromelain at a dosage of 2 tablets per day (N-acetyl cysteine 600 mg, alpha lipoic acid 200 mg, bromelain 25 mg, and zinc 10 mg) for 6 months. The study shows that women with endometriosis who wish to become pregnant and are treated with this preparation experience a significant improvement in endometriosis-related pain and require less analgesic intake. This study is limited by the absence of a control group.
Posologie
Orally
600 mg
Synergies
Properties
Purifier
N-Acetyl Cysteine is effective during acetaminophen hepatotoxicity because it restores glutathione levels in the liver and acts as an alternative substrate for the conjugation of acetaminophen's toxic metabolites.
Antioxidant
Supplementation with N-acetylcysteine increases levels of glutathione, the body's primary antioxidant. Glutathione is extremely important for detoxifying a range of toxic substances, including xenobiotics (chemicals foreign to biological systems), peroxide compounds, and other free radical-generating molecules. It thus exerts a profound protective effect on cells. The limiting factor for determining the amount of glutathione is the availability of L-cysteine. Supplementation with N-acetylcysteine simply provides L-cysteine to accelerate the resynthesis of glutathione. Furthermore, hydroxyl radicals (OH-) are well scavenged directly and efficiently by N-acetylcysteine and indirectly via glutathione production.
Usages associés
Dermatologic Effect
Acne vulgaris is a chronic skin disease characterized by follicular hyperkeratinization, hormone-mediated overproduction of sebum, and chronic inflammation of the pilosebaceous unit. It is believed that lipid damage in the skin by free radicals is responsible for the inflammatory component of acne. Recent research has shown that people suffering from acne are unable to effectively mitigate these damages as their antioxidant defense system is overwhelmed. Thus, supplementation with N-acetylcysteine allows reducing lesions through an antioxidant effect.
Usages associés
Respiratory Effect
Some clinical, animal, and in vitro research suggests that due to its antioxidant and anti-inflammatory effects, N-acetyl cysteine might have a protective effect against lung damage caused by cigarette smoke or ischemia. Additionally, N-acetylcysteine can act as a mucolytic agent and reduce the formation of phlegm.
Usages associés
Neurological
Cysteine supplementation in the brain is believed to reduce glutamatergic transmission by decreasing the amount of glutamate released in the synapse. Additionally, it has been shown that glutamate can be reduced in the brain of people with a high rate of glutamate, within an hour following oral ingestion of N-acetylcysteine. Moreover, dopamine release by neurons seems to be increased in the presence of low concentrations of N-acetylcysteine. Conversely, very high concentrations of N-acetylcysteine tend to inhibit dopamine release. There is also interest in using N-acetyl cysteine to improve compulsive behaviors and impulsivity, which are correlated with high brain concentrations of glutamate. N-acetyl cysteine seems to increase cysteine uptake, activating reverse glutamate transport in the extracellular space. The restitution of glutamate in the extracellular space inhibits the subsequent release of glutamate, which improves compulsive behaviors.
Usages associés
Immunomodulator
In isolated cells from healthy adults and HIV patients, N-acetyl cysteine increased antibody-dependent cellular cytotoxicity of neutrophils and mononuclear cells. Additionally, after treatment with N-acetyl cysteine in humans, an improvement in the phagocytic capacity of neutrophils was observed, although chemotaxis was not affected. Furthermore, N-acetyl cysteine increased the number of CD4+ cells in patients with low glutathione levels.
Antiviral
In patients with human immunodeficiency virus (HIV), N-acetyl cysteine can increase glutathione levels. An increased concentration of glutathione seems to reduce oxidative stress associated with HIV disease and improve the number and activity of CD4 T cells. Despite this effect, most clinical research suggests that N-acetyl cysteine does not provide additional benefits to HIV patients.
Anti-inflammatory
N-acetyl cysteine appears to reduce cellular production of pro-inflammatory mediators such as tumor necrosis factor alpha (TNF-alpha) and interleukin 1 (IL-1). Some in vitro research shows that N-acetyl cysteine inhibits inflammation markers, such as phospholipid metabolism and the release of pro-inflammatory cytokines. Furthermore, the control of redox-sensitive transcription factors by N-acetyl cysteine could play a role in its anti-inflammatory effects.
Usages associés
Safety dosage
Adult: 200 mg
Acetylcysteine is well tolerated. Healthy volunteers received 11.2 g of acetylcysteine per day orally for 3 months without experiencing any serious adverse effects. Oral doses up to 500 mg/kg of body weight were well tolerated without any toxicity symptoms.
Child from 2 year(s): 200 mg
Interactions
Médicaments
Nitroglycerin: strong interaction
Concomitant administration of N-acetylcysteine and intravenous nitroglycerin can cause severe hypotension and intolerable headaches. Furthermore, in vitro studies suggest that N-acetylcysteine increases the anticoagulant activity of nitroglycerin.
Precautions
Pregnant woman: avoid
Clinically, no malformative or fetotoxic effects have been reported to date. However, the tracking of pregnancies exposed to acetylcysteine is insufficient to exclude any risk. Therefore, the use of acetylcysteine during pregnancy should only be considered if necessary.
Breastfeeding woman: avoid
The data regarding the excretion of acetylcysteine and its metabolites in breast milk are not known. A risk to the breastfed child cannot be excluded. The use of acetylcysteine should be avoided during breastfeeding.
