From the Guidelines
N-acetyl cysteine (NAC) is generally not bad for health when used appropriately, as it is considered safe for most adults when taken at recommended dosages, typically 600-1800 mg daily divided into 2-3 doses 1. It serves as a precursor to glutathione, an important antioxidant in the body, and has been used medically for decades as a mucolytic agent and as an antidote for acetaminophen overdose. NAC may provide benefits for respiratory conditions, liver health, and certain psychiatric disorders. However, some people may experience mild side effects including nausea, vomiting, diarrhea, or rash.
Key Considerations
- Those taking nitroglycerin, blood thinners, or certain chemotherapy drugs should consult with healthcare providers before using NAC due to potential interactions 1.
- People with asthma should use caution as NAC might worsen symptoms in some cases.
- Pregnant or breastfeeding women should only use NAC under medical supervision.
- While NAC has a good safety profile overall, it's best to discuss its use with a healthcare provider, especially if you have underlying health conditions or take other medications.
Evidence-Based Recommendations
- The most recent and highest quality study, published in 2011, found that NAC does not prevent contrast-induced acute kidney injury (AKI) in patients undergoing angiographic procedures 1.
- Another study published in 2013 concurred with the recommendation against the use of NAC for the prevention of contrast-induced AKI, citing its potential adverse effects and lack of sound data supporting its effectiveness 1.
- However, oral NAC is inexpensive and largely devoid of adverse side effects, and its administration together with intravenous isotonic crystalloid may still be considered for high-risk patients 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Potential Health Effects of N-Acetyl Cysteine
- N-Acetyl Cysteine (NAC) is generally considered to have a well-established safety profile, with toxicity being uncommon and dependent on the route of administration and high dosages 2.
- The antioxidant and anti-inflammatory capacity of NAC is the biochemical basis used to treat several diseases related to oxidative stress and inflammation 2.
- NAC has been shown to be effective in reducing levels of tumor necrosis factor-alpha (TNF-α) and interleukins (IL-6 and IL-1β) by suppressing the activity of nuclear factor kappa B (NF-κB) 2.
Therapeutic Uses of N-Acetyl Cysteine
- NAC is widely used to treat paracetamol overdose and as a mucolytic compound 3, 2.
- It has been used to treat various diseases, including chronic obstructive pulmonary disease (COPD), cancer, heart disease, HIV infection, heavy metal toxicity, and other diseases characterized by free radical oxidant damage 4, 5, 6.
- NAC has also been shown to be of some value in treating Sjogren's syndrome, smoking cessation, influenza, hepatitis C, and myoclonus epilepsy 4.
Mechanisms of Action
- NAC acts as a precursor of glutathione, increasing the intracellular concentration of this crucial biothiol responsible for cellular redox imbalance 2, 6.
- It has anti-infective properties and specific antioxidant and anti-inflammatory effects in the airways 5.
- The mechanisms leading to the protective role of NAC against acute exacerbation of COPD (AECOPD) need to be adequately addressed, and may involve activation of antioxidant pathways, inhibition of pro-oxidant and inflammatory pathways, and modulation of human bronchial tone 5.