Nac
Also known as n-acetyl cysteine, n-acetylcysteine, nac
Key takeaways
- NAC may reduce COPD exacerbations and improve lung function (PMID: 39349461, 26324807).
- NAC regulates Th17/Treg balance to improve inflammatory response in COPD patients (PMID: 34258270).
- Efficacy for bipolar and major depressive disorder remains inconsistent across multiple meta-analyses (PMID: 39504621, 32767039).
What the research shows
AI-synthesized from 41 peer-reviewed sources · Updated 2025
N-Acetylcysteine (NAC) is an antioxidant and mucolytic agent used across various medical contexts. Research indicates efficacy in respiratory health and as an adjuvant for specific infections, though its efficacy in psychiatric conditions remains inconsistent.
By condition
Respiratory (COPD/Chronic Bronchitis)
Moderate
NAC acts as a mucolytic and antioxidant, showing efficacy in reducing exacerbations and improving inflammatory responses in COPD patients.
Mental Health (Bipolar/Major Depression)
Weak
Meta-analyses show inconsistent results, with some suggesting benefit for bipolar depression while others indicate no significant superiority over placebo.
H. pylori Eradication
Moderate
Used as an adjuvant therapy to improve the eradication rates of Helicobacter pylori.
Acute Liver Failure (non-paracetamol)
Insufficient
Cochrane reviews indicate limited evidence for its efficacy in non-acetaminophen related liver failure.
Effective doses
Specific dose ranges were not detailed in the provided abstracts, though high-dose administration was specifically noted for COPD (PMID: 39349461).
Safety & interactions
No specific contraindications provided in the abstracts; generally used as an adjunctive treatment.
Limitations
Research on psychiatric applications is contradictory, and evidence for non-paracetamol liver failure is limited. Many studies focus on adjuvant use rather than monotherapy.
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Research evidence
Showing top 10 of 41 sources, sorted by quality
**Fontes et al., 2019** | Cochrane Database Syst Rev | Meta Analysis Fontes Luís Eduardo S, Martimbianco Ana Luiza C, ... Riera Rachel. N-acetylcysteine as an adjuvant therapy for Helicobacter pylori eradication. Cochrane Database Syst Rev.…
Evidence for the treatment of patients with mild-to-moderate chronic obstructive pulmonary disease (COPD) is limited. The efficacy of N-acetylcysteine (an antioxidant and mucolytic agent) for patients with mild-to-moderate COPD is uncertain…
**Siu et al., 2020** | Cochrane Database Syst Rev | Meta Analysis Siu Jacky Tp, Nguyen Trina, Turgeon Ricky D. N-acetylcysteine for non-paracetamol (acetaminophen)-related acute liver failure. Cochrane Database Syst Rev. 2020-Dec-09;12(12):…
In order to clarify the possible role of N-acetylcysteine (NAC) in the treatment of patients with chronic bronchitis and chronic obstructive pulmonary disease (COPD), we have carried out a meta-analysis testing the available evidence that N…
BACKGROUND: A phasic dysregulation of mitochondrial bioenergetics may operate in bipolar disorder, increased in mania and decreased in depression. We aimed to examine efficacy of two add-on treatments in bipolar depression: N-acetylcysteine…
BACKGROUND: Results on whether N-acetylcysteine (NAC) ameliorates depression in patients with psychiatric problems, such as bipolar disorder and major depressive disorder, remain inconsistent, and several new studies have recently been publ…
**Soghier et al., 2006** | Cochrane Database Syst Rev | Meta Analysis Soghier L M, Brion L P. Cysteine, cystine or N-acetylcysteine supplementation in parenterally fed neonates. Cochrane Database Syst Rev. 2006-Oct-18;2006(4):CD004869 BACKG…
OBJECTIVES: Previous studies and meta-analyses suggested that N-acetylcysteine (NAC) was superior to placebo in improving depression in bipolar disorder. However, more recent data, including two larger trials, found that NAC was no more eff…
RATIONALE: It remains unclear whether using N-acetylcysteine as an adjunctive treatment has any benefit for bipolar depression and major depressive disorder. OBJECTIVES: A systematic review and random-effect meta-analysis of double-blind, r…
INTRODUCTION: N-acetylcysteine (NAC) is a mucolytic agent with antioxidant properties. Oxidative stress is a key pathogenic mechanism in chronic respiratory conditions such as COPD and chronic bronchitis (CB). In these meta-analyses we inve…
Frequently asked questions
What is N-Acetylcysteine (NAC) and what is it used for?
N-Acetylcysteine (NAC) is an antioxidant and mucolytic agent used across various medical contexts. It is primarily researched for its potential benefits in respiratory health, such as reducing exacerbations in COPD, and as an adjuvant therapy for specific infections like H. pylori.
Does NAC help with COPD or chronic bronchitis?
There is moderate evidence that NAC acts as a mucolytic and antioxidant to reduce exacerbations and improve inflammatory responses in COPD patients. Research indicates it may help regulate the immune balance to improve lung function, though specific high-dose protocols should be discussed with a doctor.
Is NAC effective for mental health conditions like depression or bipolar disorder?
The evidence for NAC in treating bipolar disorder or major depression is weak and inconsistent. While some meta-analyses suggest potential benefits for bipolar depression, others indicate no significant superiority over a placebo, meaning research is mixed and more study is needed.
Can NAC help eradicate H. pylori infections?
There is moderate evidence that NAC can be used as an adjuvant therapy to improve the eradication rates of Helicobacter pylori. It is generally used alongside standard treatments rather than as a standalone cure, and you should consult a healthcare provider for proper management.
Is NAC safe to take, and are there any side effects?
NAC is generally used as an adjunctive treatment with no specific contraindications documented in the provided evidence. However, because safety data is limited, pregnant individuals or those with existing health conditions should consult a healthcare provider before use to ensure it is appropriate for their situation.
Does NAC interact with other medications?
No drug interactions have been documented for N-Acetylcysteine in the available evidence. Despite this, it is important to consult a healthcare provider before starting any new supplement, especially if you are currently taking other medications to avoid potential unforeseen effects.
Who should avoid taking NAC?
While no specific contraindications are listed, individuals with acute liver failure (non-paracetamol related) have insufficient evidence supporting its efficacy, so caution is advised. Pregnant individuals, those on medications, or people with specific medical conditions should always consult a healthcare provider before using NAC.