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We Review The Use Of NAC For Asthma

In the United States alone, nearly 25 million people suffer from asthma. Are you one of them? If you have minor asthma and don’t enjoy always having to have an inhaler within arm’s reach, then you may want to look for other solutions for managing your symptoms year-round.

Since oxidative stress plays a role in asthmatic reactions, many affected individuals use antioxidants along with standard treatment to minimize the distress that the condition can cause. One antioxiant, in particular, has risen in popularity towards the treatment of conditions correlated with oxidtive stress – NAC. 

While there is plenty of research proving that oxidative stress is indeed correlated with some instances of asthma, the research is a bit muddy when it comes to determining the efficacy of NAC towards asthma in humans as most studies have been conducted in animals. Despite this, many people believe that NAC works, and several studies in animals display its potential.

Here, I’ll review what research currently shows about the efficacy of NAC in treating asthma and discuss the typical dosage that’s prescribed for individuals with similar conditions.

Why Do People Use NAC For Asthma?

Oxidative stress affects asthma specifically because it irritates the airways. If you have asthma and this stress leads to inflammation in your airways, bronchospasms can be stimulated and mucus secreted – leading to an adverse reaction. Because of this, a popular natural approach to treating asthma is the use of antioxidants.

N-acetyl cysteine (NAC) is a precursor for the amino acid L-cysteine. When ingested, NAC bonds with glycine and glutamine to cause the body to produce more significant amounts of a powerful antioxidant called glutathione than it otherwise would. This antioxidant can help protect and repair cells from damage caused by the free radicals that come with oxidative stress. 

So, when you regularly take NAC, there is the potential that the benefits of the extra antioxidants can be provided to keep the oxidative stress at bay. This makes it a natural form of co-treatment for asthma, and it may be something worth trying.

What Does Research Say About NAC For Asthma?

As of now, research has mixed results regarding the effectiveness of NAC for asthma treatment. While plenty of studies have been done on animals, none have been conducted in humans that confirm NAC’s efficacy.

Here’s what we currently know about NAC for asthma and similar conditions based on available studies:

  • One study was conducted in multiple mice to see the effectiveness of NAC on airway hyper-responsiveness (AHR) and the accumulation of inflammatory cells in the airway. NAC reduced airway hyper-responsiveness and significantly decreased neutrophil and eosinophil count in bronchoalveolar lavage fluid as well as inflammatory cytokines (IL-13 and IL-5). Thus, it was concluded that NAC for asthma therapy had beneficial preventative effects.
  • Another study performed at Aristotle University on rats with allergic rhinitis showed that NAC has the potential to help reduce allergen-induced nasal inflammatory cascade. During the study, NAC significantly inhibited the accumulation of inflammatory cells and downregulated iNOS expression and TNF-α serum levels.
  • A study conducted in rats with antigen-induced asthma showed that oral NAC showed beneficial effects including the prevention of airway hyperreactivity to 5-hydroxytryptamine at 24 hours after antigen challenge along with a reduction in eosinophils.

While some studies conducted on rats and mice have shown positive results of NAC use, no long-term studies on the prevention of recurrent asthma attacks have been done. It has yet to be determined if NAC can reduce inflammation and mucous plugging to make it a viable form of treatment.

Although rare, it should be mentioned that one study was conducted in asthmatic patients who inhaled or used intravenous N-acetylcysteine. Fatal bronchospasms were reported in multiple patients but this could have been avoided if the concentration had not exceeded 10% and concomitant beta2-selective bronchodilators were utilized. As of now, there hasn’t been any reported risk of fatal bronchospasms in those who took NAC orally.

What Is The Standard Dosage Of NAC For Asthma?

As of now, the maximum licensed dose for NAC is 600 milligrams (mg) per day when treatment requires chronic use, such as in respiratory diseases. However, at least 41 studies have been conducted that used over 600 mg and up to 3,000 mg per day, with great attention being paid to the safety of the participants.

Most of these studies prescribed NAC orally and were used in patients that had chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, bronchiectasis, chronic bronchitis, and cystic fibrosis. Overall, there didn’t appear to be any danger associated with higher doses, although some gastrointestinal symptoms were reported which was no more than with the control group.

Also read our review on the best NAC supplement.

Editor’s note: we are regularly updating this article. If you see any problems, weird interpretations of the data, or just want to say hi, please reach out to

Photo by HayDmitriy

About the author

Christine is a certified personal trainer and nutritionist with an undergraduate degree from Missouri State University. Her passion is helping others learn how strong and healthy they can become by transforming their daily habits. Christine spends most of her time in the gym and learning how she can influence others through positivity!

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