Nicotine e-cigarettes show potential in helping smokers quit, but health experts continue to caution against their use as smoking cessation aids.

By Alyx Arnett

Tobacco use is the leading cause of preventable death in the US, causing about one in five deaths each year.1 While there are many smoking cessation tools available—from FDA-approved medications to behavioral support—nicotine electronic cigarettes (e-cigarettes) are increasingly being considered as a promising alternative for traditional smokers seeking to quit. 

E-cigarettes entered the US market around 2007 and, as of 2018, were used by about 3.2% of adults, down from 4% in 2014, according to the Centers for Disease Control and Prevention (CDC). The CDC also notes that about half of adults who use e-cigarettes also smoke regular cigarettes and that some traditional smokers have turned to e-cigarettes for help quitting.2 A typical e-cigarette—also called a vape—comprises a battery, a heating element, and a liquid reservoir. When the device is activated, the heating element vaporizes the liquid, which usually contains nicotine, flavorings, and other chemicals. The user then inhales the resulting aerosol, which is delivered directly into the lungs.

New research points to e-cigarettes as a more effective way to quit smoking; however, some organizations, advocacy groups, and policymakers continue to raise concerns about their potential health risks, addictiveness, and lack of long-term studies. 

Vaping Beats Nicotine Replacement for Quitting

Researchers in a new review update, published in Cochrane Database of Systematic Reviews,3 sought to provide answers to cigarette smokers, healthcare providers, and regulators as to whether e-cigarettes can aid in smoking cessation and what risks they pose. 

After reviewing 78 completed studies, including 40 randomized controlled trials, representing 22,052 participants, researchers found “high-certainty” evidence that e-cigarettes with nicotine increased quit rates compared to nicotine replacement therapy and that they were also more effective than other cessation methods.  

“Our findings suggest that people who smoke will increase their chances of successfully quitting smoking if they use a nicotine-containing e-cigarette to help them quit, compared to trying to quit with no support or with traditional nicotine replacement therapy,” said author Jamie Hartmann-Boyce, MA, DPhil, associate professor at Nuffield Department of Primary Care Health Sciences, Medical Sciences Division, University of Oxford. 

The studies compared e-cigarettes with nicotine replacement therapy, such as patches or gum; varenicline (a smoking cessation drug); e-cigarettes without nicotine; other types of nicotine-containing e-cigarettes; behavioral support, such as advice or counseling; and no support.

Most studies took place in the US (34), the UK (16), and Italy (eight). The researchers’ primary outcome measures were abstinence from smoking after at least six months, adverse events, and serious adverse events. 

E-cigarettes Outperformed All Other Quit Methods

Researchers found that traditional cigarette smokers were more likely to quit for at least six months when using nicotine e-cigarettes compared to other methods.

There was high certainty that quit rates were higher in people randomized to nicotine e-cigarettes than in those randomized to nicotine replacement therapy (risk ratio [RR]1.63, 95% confidence interval [CI] 1.30 to 2.04) and moderate-certainty evidence, limited by imprecision, that quit rates were higher in people randomized to nicotine e-cigarettes than to e-cigarettes without nicotine (RR 1.94, 95% CI 1.21 to 3.13).

Compared to behavioral support only or no support, quit rates were higher for participants randomized to nicotine e-cigarettes (RR 2.66, 95% CI 1.52 to 4.65). However, researchers note this finding was of “very low certainty” due to issues with imprecision and risk of bias. 

The findings indicate nine to 14-of-100 people using nicotine e-cigarettes to quit smoking might successfully stop, compared to six of 100 people using nicotine replacement therapy, seven of 100 using e-cigarettes without nicotine, or four of 100 people having no support or behavioral support only.

“To the best of our knowledge, our review—as a living systematic review—incorporates the most up-to-date evidence, meaning it includes more studies than many of the other reviews in this area,” said Hartmann-Boyce. The review included 17 studies that were new to the update. 

Insights into Adverse Events  

In addition to investigating e-cigarettes’ effectiveness, investigators also looked at adverse events and serious adverse events reported in the studies. 

Researchers found some evidence that non-serious adverse effects were more common in people receiving nicotine e-cigarettes compared to behavioral support only or no support, and a “low number” of unwanted effects, including serious effects, were found in studies comparing nicotine e-cigarettes to nicotine replacement therapy. 

Researchers say there’s likely no difference in the number of non-serious unwanted effects between users of nicotine e-cigarettes and non-nicotine e-cigarettes. 

The most commonly reported unwanted effects with nicotine e-cigarettes were throat or mouth irritation, headache, cough, and feeling sick. The symptoms reduced over time. The overall incidence of serious adverse events was low, and researchers did not detect evidence of “serious harm” from nicotine e-cigarettes, though the longest follow-up was two years, and the number of studies was small. 

Researchers point out that e-cigarette users inhale nicotine in a vapor rather than smoke and claim that, because e-cigarettes do not burn tobacco, they “do not expose users to the same levels of chemicals that can cause diseases in people who smoke conventional cigarettes.” 

While the review gleaned insights into potential short-term safety effects, more data on long-term effects is needed, said Hartmann-Boyce.

“Though we now have clear evidence nicotine-containing e-cigarettes can help people quit smoking, we do need more data on safety. The evidence we have so far overwhelmingly suggests that, though not risk-free, nicotine e-cigarettes are considerably less harmful than smoking,” she said. “On a simple level, this means that someone who smokes who switches to an e-cigarette is likely to reduce their risks of preventable diseases. It also means that people who do not smoke or would not have otherwise smoked should not use e-cigarettes.” 

A Serious Lack of Long-term Health Studies

One of the main concerns regarding the use of e-cigarettes as a smoking cessation tool is the dearth of studies on their long-term effects. This is mainly because e-cigarettes have not been in use for a sufficient period of time to generate critical and comprehensive longitudinal data. 

“We didn’t know really the full effects of tobacco smoking for quite a few years, maybe several decades, before we could ultimately prove that they lead to COPD and lung cancer,” said Albert A. Rizzo, MD, FCCP, FACP, chief medical officer at the American Lung Association. “So, from a Lung Association standpoint, since the same chemicals in many ways are used by individuals with e-cigarettes and vaping, the concern is the same thing’s going to be found—not now but in the future.”

Recent research has attempted to investigate the safety of e-cigarettes, but investigators have been limited by a lack of studies. A review published in npj Primary Care Respiratory Medicine4 sought to determine the effect of vaping on lung function, but researchers found only eight studies, all of which were small, and only one examined longer-term outcomes (three and a half years follow-up). In general, these studies suggested there were no acute changes associated with vaping, but airway resistance and conductance may be influenced by e-cigarettes. Researchers concluded that the results were suggestive, and further research must be conducted. 

A study published in the American Heart Association journal Circulation5 found no significant differences in heart attacks, heart failure, or strokes among dual-smokers—those using a combination of traditional cigarettes and e-cigarettes—compared to those who smoked traditional cigarettes only. Those who exclusively used e-cigarettes were 30%-40% less likely to report cardiovascular disease events, but researchers said the number of heart-related events was too small to draw any definitive conclusions.

“The solid facts are that we don’t have long enough term follow-up,” said Rizzo. “We do know that inflammation occurs in the lungs of individuals who inhale e-cigarettes. And we know that the emissions from e-cigarettes contain harmful chemicals, very much similar to if not the exact same as tobacco smoke. So those are our facts that we do know. We just don’t have long-term evidence of developing diseases, such as lung cancer, just because these things have not been out long enough. They haven’t been studied in a rigorous manner.” 

Rizzo also notes that studies on e-cigarettes are especially challenging due to difficulties in making direct comparisons. “We don’t know what the constant is between them because each cigarette contains different chemicals and different amounts of nicotine, and it’s not advertised as to what’s actually in them. So, it’s hard to compare the results of something when you have no control over what individuals are using or how they’re using them,” he said.

With so many unknowns regarding e-cigarettes, the American Lung Association remains firm in its position that they should not be relied upon as a smoking cessation aid. Rizzo said any inhaled substance with nicotine that isn’t marketed with FDA approval or shows what its contents are can be harmful to the lungs. To effectively manage a nicotine addition, the association recommends using FDA-approved medications in combination with counseling and a strong support system.


Alyx Arnett is associate editor of RT. For more information, contact [email protected].

  1. Tobacco-Related Mortality. Centers for Disesase Control and Prevention. 28 April 2020.
  2. Adult Smoking Cessation—The Use of E-CIgarettes. Centers for Disease Control and Prevention. 23 Jan 2020.
  3. Hartmann-Boyce, J., Lindson, N., Butler, A. R., et al. Electronic cigarettes for smoking cessation. Cochrane Database of Systematic Reviews. 2022.
  4. Honeycutt, L., Huerne, K., Miller, A. et al. A systematic review of the effects of e-cigarette use on lung function. npj Prim. Care Respir. Med. 2022;32, 45.
  5. Berlowitz, J. B., Xie, W., Harlow, A. F., et al. E-Cigarette Use and Risk of Cardiovascular Disease: A Longitudinal Analysis of the PATH Study (2013–2019). Circulation. 2022; 145(20),1557–1559.

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