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How does vaping affect FeNO levels?

Research has shown that cigarette smoking can reduce FeNO levels by around 60%1 but what about vaping? Electronic or ‘e-cigarettes’ have gained significant popularity in recent years as an alternative to traditional tobacco smoking. However, concerns have been raised regarding the potential impact on public health. One aspect of particular interest to the respiratory community is whether vaping affects fractional exhaled nitric oxide (FeNO) levels. In this article, we explore the evidence.

FeNO is a biomarker that measures the concentration of nitric oxide (NO) in exhaled breath.2 Results play a crucial role in assessing airway inflammation, one of the main features of Type 2 asthma, which accounts for the majority of cases.3,4 In fact, elevated FeNO levels indicate that a diagnosis of asthma is 7x more likely.5 So where does vaping fit into the asthma assessment process? Like smoking, vaping should be taken into account but it’s unclear how much it affects FeNO.

With vaping on the rise, several studies have investigated the topic. Research led by Kandhola in 2022 uncovered changes in FeNO after vaping over a 30-minute period.6 The results showed a significant change in median FeNO levels over time (p=0.019), revealing a decrease in FeNO from baseline during observation. A significant increase took place from minute 30 to 45, suggesting the effect of vaping could be transient. When asthmatics are compared to non-sufferers, some reports indicate a decrease in FeNO in healthy subjects and an increase in those with asthma. In contrast, other studies have reported a decrease in smokers with pulmonary diseases so it seems as though it is a matter of case-by-case assessment.6

In 2020, Traboulsi led research that highlights how the extent to which NO is altered by exposure to e-cigarettes can be divisive.7 This team reported that, although individuals exposed to e-cigarettes had reduced FeNO immediately after vaping – indicating a reduction in airway inflammation – a separate study found there was no significant difference in FeNO following exposure to a laboratory-made mixture of propylene glycol and glycerin, the most common humectants used in electronic cigarette liquids.7,8

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While research remains conflicted, it is important to remember that the long-term effect of vaping on FeNO levels is still not well understood. Vaping involves inhaling liquids that often contain various chemicals, including nicotine, flavourings, and other additives that may result in lung or respiratory disease.9

“Any product with ‘cigarette’ in its name should be a red flag for anyone who has asthma or allergies,” stresses the Allergy and Asthma Network of America.9 Asthma + Lung UK agrees, stating that although research suggests vaping causes less exposure to the toxins that cause lung disease than smoking tobacco, e-cigarettes are not risk-free. “We know that vaping can cause inflammation in the airways, which might cause harm over time,” the charity says.10

In short, the current body of research suggests that vaping can have an impact on FeNO levels, albeit to a lesser extent than traditional smoking. Exposure to vaping seems to cause a temporary decrease in FeNO levels according to some studies, but these changes appear to be transient.6,7,11 However, the long-term effects of vaping on FeNO levels and airway inflammation require further investigation.

Learn more about the role FeNO plays in assessing airway inflammation for improved asthma care here.

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1. Prof. Kjell Alving. Factors affecting FeNO: confounders vs determinants. Available at;
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3. Maspero J et al. Type 2 inflammation in asthma and other airway diseases. ERJ Open Research. 2022;8(3).
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5. Wang Z et al. Agency for Healthcare Research and Quality (AHRQ). The clinical utility of fractional exhaled nitric oxide (FeNO) in asthma management. Comparative Effectiveness Reviews, 197. 2017.
6. Kandhola A et al. Measurement and Changes of FeNO Levels While Vaping with a Brief Education Intervention Session. ERJ Open Research. 2022.
7. Traboulsi H et al. Inhalation toxicology of vaping products and implications for pulmonary health. International journal of molecular sciences. 2020;21(10):3495.
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9. Allergy & Asthma Network. Can you smoke if you have asthma ? Available at ; Accessed; June 2023
10. Asthma + Lung UK. Vaping and e-cigarettes. Available at; Accessed; June 2023
11. Schober W et al. Use of electronic cigarettes (e-cigarettes) impairs indoor air quality and increases FeNO levels of e-cigarette consumers. International journal of hygiene and environmental health. 2014;217(6):628-37.