N-acetyl-L-cysteine: benefits, dosage, contraindications
Other name(s)
Cysteine hydrochloride
Scientific name(s)
NAC
Family or group:
Amino acids
Indications
Scoring methodology
EFSA approval.
Bronchitis ✪✪✪✪✪
Taking N-acetyl cysteine at a dose of 1200-1500 mg/day orally for 4 months appears to reduce cough and improve lung capacity in patients with sulfur mustard-induced bronchitis. In addition, taking N-acetyl cysteine orally at doses of 400 to 1200 mg per day for 3 to 6 months appears to reduce the risk of acute exacerbations of chronic bronchitis. However, taking it for a shorter duration does not seem to have a beneficial effect on chronic bronchitis. nn
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 tests.
The effect of oral N-acetylcysteine in chronic bronchitis: a quantitative systematic review.
Autism ✪✪✪✪✪
Some clinical research shows that taking N-acetylcysteine at 900 mg per day for 4 weeks, then 900 mg twice daily for 4 weeks, then 900 mg three times daily for 4 weeks improves symptoms of irritability in children with autism spectrum disorder. Additional clinical research shows that taking N-acetylcysteine at 1200 mg per day in combination with risperidone (an antipsychotic) for 8 weeks is more effective than risperidone alone at reducing irritability in children and adolescents with autism spectrum disorder. Although N-acetylcysteine appears to be slightly effective in reducing irritability, it does not appear to improve other symptoms associated with autism spectrum disorder.
Posologie
Orally
900 - 2700 mg
3 - months
A randomized controlled pilot trial of oral N-acetylcysteine in children with autism.
A randomized, double-blind, placebo-controlled trial of a fixed dose of N-acetylcysteine in children with autistic disorder.
Chronic obstructive pulmonary disease ✪✪✪✪✪
The N-acetylcysteine solution for inhalation is approved by the FDA (Food and Drug Administration) for the management of chronic bronchopulmonary diseases, such as chronic obstructive pulmonary disease (COPD). A meta-analysis of 12 clinical trials shows that N-acetylcysteine, administered for at least 6 months, reduces the number of patients suffering at least one exacerbation of chronic obstructive pulmonary disease (COPD) by 15% compared with placebo; however, it is not associated with a reduction in the COPD exacerbation rate or with improvement in measures of lung function. Smaller studies have shown a higher improvement rate of 23% to 40%, with the greatest efficacy observed in patients who are not already taking inhaled corticosteroids. N-acetylcysteine has been used at 400 to 1200 mg per day in divided doses for 4 to 6 months. It has also been used nebulized, on two alternate 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 31 to 45% reduction in hair-pulling symptoms in people with trichotillomania with supplementation of 1,200 to 2,400 mg of N-acetylcysteine for 12 weeks. However, in children, taking N-acetylcysteine at doses up to 2,400 mg per day for 12 weeks does not appear to improve hair-pulling compared with placebo.
Posologie
Oral
1,200 - 2,400 mg
12 - weeks
Detoxification ✪✪✪✪✪
Supplementation with 200 to 800 mg of N-acetylcysteine for 3 months in workers exposed to occupational levels of lead can reduce lead accumulation in red blood cells and the resulting oxidative sequelae, and can also improve glutathione levels in red blood cells.
Posologie
Oral
200 - 800 mg
3 - months
Smoking cessation ✪✪✪✪✪
A double-blind study showed that after about two weeks of supplementation with 2,400 mg of N-acetylcysteine, cigarette consumption appeared to decrease voluntarily by about 25%.
Posologie
Oral
2,400 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
Oral
1200 - 1200 mg
2 - months
Obsessive-compulsive disorder ✪✪✪✪✪
Preliminary clinical research shows that taking N-acetylcysteine at a dose of 1000 mg twice daily together with 200 mg/day of fluvoxamine (an antidepressant) for 10 weeks moderately reduces overall obsessive-compulsive disorder symptoms and obsessive symptoms compared with fluvoxamine plus placebo. However, adding N-acetylcysteine is not associated with improvement in compulsion symptoms, nor with a statistically significant increase in partial or full responses compared with fluvoxamine alone.
Posologie
Oral
2000 mg
10 - weeks
Substance use disorder ✪✪✪✪✪
Some preliminary clinical evidence suggests that taking 600 mg of N-acetylcysteine twice daily for two days reduces cocaine craving compared with placebo in people with cocaine dependence. However, other preliminary clinical evidence suggests that taking oral N-acetylcysteine 600 mg twice daily for 2 days does not reduce cravings or withdrawal symptoms compared with placebo in patients hospitalized for cocaine dependence. On the other hand, a supplementation of 2,400 mg appears to reduce symptoms of marijuana dependence, although the reduction in symptoms is not substantial.
Posologie
Oral
1200 - 2400 mg
2 - days
Endometriosis ✪✪✪✪✪
The patients began treatment with the combination: N-acetylcysteine, alpha-lipoic acid and bromelain at a dose of 2 tablets per day (N-acetylcysteine 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 who are treated with this preparation experience a significant improvement in endometriosis-associated pain and require less use of analgesics. This study is limited by the absence of a control group.
Posologie
Oral
600 mg
Synergies
Properties
Depurative
N-acetyl-L-cysteine is effective in cases of acetaminophen-induced hepatotoxicity because it restores glutathione levels in the liver and acts as an alternative substrate for the conjugation of the toxic metabolites of acetaminophen.
Antioxidant
N-acetylcysteine supplementation increases glutathione levels, 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 molecules that generate free radicals. It therefore exerts a profound protective effect on cells. The limiting factor in determining the amount of glutathione is the availability of L-cysteine. N-acetylcysteine supplementation simply provides L-cysteine to speed glutathione resynthesis. In addition, hydroxyl radicals (OH-) are effectively and directly scavenged by N-acetylcysteine as well as indirectly via glutathione production.
Usages associés
Dermatologic effect
Acne vulgaris is a chronic skin disease characterized by follicular hyperkeratinization, hormonally mediated overproduction of sebum, and chronic inflammation of the pilosebaceous unit. Damage to skin lipids by free radicals is thought to be responsible for the inflammatory component of acne. Recent research has shown that people with acne are unable to adequately mitigate this damage because their antioxidant defense system is overwhelmed. Thus, supplementation with N-acetylcysteine can reduce lesions through an antioxidant effect.
Usages associés
Respiratory effect
Some clinical, animal, and in vitro studies suggest that due to its antioxidant and anti-inflammatory effects, N-acetylcysteine may have a protective effect against lung injury caused by cigarette smoke or ischemia. In addition, N-acetylcysteine can act as a mucolytic agent and reduce sputum production.
Usages associés
Neurological
It is thought that an increase in cysteine in the brain can reduce glutamatergic transmission by decreasing the amount of glutamate released into the synapse. In addition, it has been shown that glutamate can be reduced in the brains of people with high glutamate levels within an hour after oral ingestion of N-acetylcysteine. Moreover, dopamine release from neurons appears 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-acetylcysteine to improve compulsive behaviors and impulsivity, which are correlated with high brain glutamate concentrations. N-acetylcysteine appears to increase cysteine uptake, which activates reverse glutamate transport into the extracellular space. Restoration of glutamate in the extracellular space inhibits subsequent glutamate release, which improves compulsive behaviors.
Usages associés
Immunomodulatory
In isolated cells from healthy adults and from patients with HIV, N-acetylcysteine increased antibody-dependent cell-mediated cytotoxicity of neutrophils and mononuclear cells. In addition, after treatment with N-acetylcysteine in humans, an improvement in neutrophil phagocytic capacity was observed, although chemotaxis was not affected. Furthermore, N-acetylcysteine increased the number of CD4+ cells in patients with low glutathione levels.
Antiviral
In patients infected with the human immunodeficiency virus (HIV), N-acetyl cysteine can increase glutathione levels. An increased glutathione concentration appears to reduce the oxidative stress associated with HIV disease and improve the number and activity of CD4 T lymphocytes. Despite this effect, most clinical research suggests that N-acetyl cysteine does not provide additional benefits to HIV patients. nn
Anti-inflammatory
N-acetyl cysteine appears to reduce the 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 markers of inflammation, such as phospholipid metabolism and the release of pro-inflammatory cytokines.nnIn addition, the regulation of redox-sensitive transcription factors by N-acetyl cysteine may play a role in its anti-inflammatory effects. nn
Usages associés
Safe dosage
Adult: 200 mg
N-acetylcysteine is well tolerated. Healthy volunteers received 11.2 g of N-acetylcysteine per day orally for 3 months without experiencing serious adverse effects. Oral doses up to 500 mg/kg of body weight were well tolerated without any signs of toxicity.
Children aged 2 years and older: 200 mg
Interactions
Médicaments
Nitroglycerin: strong interaction
Concurrent administration of N-acetylcysteine and intravenous nitroglycerin can cause severe hypotension and intolerable headaches. In addition, in vitro research suggests that N-acetylcysteine increases the anticoagulant activity of nitroglycerin.
Precautions
Pregnant women: avoid
In clinical use, no teratogenic or fetotoxic effects have been observed to date. However, follow-up 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: avoid
Data on the excretion of acetylcysteine and its metabolites into breast milk are not known. A risk to the breastfed infant cannot be excluded. The use of acetylcysteine should be avoided during breastfeeding.
