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 Table of Contents  
Year : 2023  |  Volume : 15  |  Issue : 5  |  Page : 418-423

Safety of E-cigarettes and its effectiveness in smoking cessation: A systematic review

1 Department of Oral Medicine and Radiology, D Y Patil Dental School, Pune, Maharashtra, India
2 Department of Biochemistry, D Y Patil Dental School, Pune, Maharashtra, India
3 Department of Oral Pathology and Microbiology, D Y Patil Dental School, Pune, Maharashtra, India
4 Department of Oral Medicine and Radiology, Dr D Y Patil Vidyapeeth, Dr D Y Patil Dental College and Hospital, Pune, Maharashtra, India

Date of Submission09-Feb-2023
Date of Decision05-Aug-2023
Date of Acceptance21-Aug-2023
Date of Web Publication30-Oct-2023

Correspondence Address:
Dr. Anagha V Shete
Department of Oral Medicine and Radiology, D Y Patil Dental School, Lohegaon, Pune, Maharashtra 412105
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jioh.jioh_39_23

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Aim: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria, the main goal of our study is to analyze the safety of e-cigarettes and their relationship to quitting smoking. Materials and Methods: From January 2011 to December 2022, a thorough search of the Cochrane Library, PubMed, Scopus, Web of Science, and Scopus databases was carried out. Using PRISMA criteria, we evaluated 25 review papers, three randomized controlled trials, and three cross-sectional studies in this review, which analyzed 12,210 study participants. Although language did not restrict search results, all discovered studies were in English. The threat of bias and level of evidence were determined for each selected study. Results: Our systematic review showed a bigger rate of smoking cessation, i.e., 20%, with the use of E-cigarettes, suggestive of their contribution to smoking cessation. We found a correlation between cessation of smoking and E-cigarettes with nicotine, which suggests that they may prove as an effective alternative smoking cessation aid. The count of cigarettes used per day is lessened, so they may be used to reduce the harm caused by tobacco. Conclusion: Although not formally monitored, E-cigarettes can help smokers unable or unwilling to quit to remain abstinent or reduce their cigarette consumption. The toxic substances and chemicals within E-cigarettes are not clearly labeled, and hence, their safety is not guaranteed.

Keywords: E-cigarettes, electronic cigarettes, electronic nicotine delivery system (ENDS), quitting smoking

How to cite this article:
Shete AV, Hajarnavis AM, Shete MV, Nerkar-Rajbhoj AA, Sande A, Channe PP. Safety of E-cigarettes and its effectiveness in smoking cessation: A systematic review. J Int Oral Health 2023;15:418-23

How to cite this URL:
Shete AV, Hajarnavis AM, Shete MV, Nerkar-Rajbhoj AA, Sande A, Channe PP. Safety of E-cigarettes and its effectiveness in smoking cessation: A systematic review. J Int Oral Health [serial online] 2023 [cited 2023 Dec 4];15:418-23. Available from:

  Introduction Top

The main cause of pathologies, such as different kinds of cancer, cardiovascular, and respiratory illnesses, is cigarette smoking.[1] More than 1 billion people smoke worldwide, and the frequency of smoking is increasing in emerging nations, according to the WHO. In nations with middle- and low-income levels, 80% of smokers live.[2]

Herbert A. Gilbert received a patent for the electronic cigarette (also known as an ENDS) in 1963.[3] E-cigarettes are marketed as being less hazardous than traditional cigarettes due to the novelty of the technology, the availability of numerous delicious flavor combinations, and marketing tactics.[4] Electronic nicotine delivery systems include electronic cigarettes or E-cigarettes. They run on batteries and vaporize nicotine solutions (E-liquid) and other substances like propylene glycol, vegetable glycerine, and flavoring agents). Heat is generated, and the aerosol produced, in turn, is inhaled by users. This is called vaping. E-cigarettes look similar to traditional smoking products like cigarettes, cigars, pipes, and pens, which are based on combustion.[5]

We urged for this study as a large number of adolescents and adults these days are inclined to use of E-cigarettes, and there has been a massive debate about its use, misuse, advantages, and side effects. Not many systematic reviews are currently available in the literature to give a clearer scenario.

Null hypothesis—E-cigarettes are not safe and are not effective for the purpose of cessation of smoking.

  Materials and Methods Top

To evaluate the relationship between E-cigarettes and smoking cessation among adult smokers, we conducted a systematic evaluation of randomized controlled trials (RCTs) and observational studies. There was a retrospective analysis, and the trial lasted for 8 months.

Search tactics and study choice

[Figure 1] shows the systematic approach taken for identifying and excluding records from all levels of the literature search. The phrases “safety/efficacy of E-cigarettes/electronic cigarettes” AND “electronic cigarettes AND/OR smoking cessation, e-cigarette AND/OR electronic cigarette/e-cig” were used to search PubMed, Google Scholar, and Web of Science databases. 2011 through 2022 saw searches of the database. The whole search turned up 340 items, 59 of which were flagged as duplicates, 163 weren’t included, and 6 had the complete text (three RCTs and three cross-sectional studies) were included. Twenty-five review articles were also considered against the inclusion criteria.
Figure 1: Search strategy for identifying the records

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PICO analysis

Using PICO analysis, the following research question was established:

P (patient): Patients over the age of 18 who utilized electronic cigarettes to quit smoking.

I (intervention): E-cigarettes for smoking cessation.

C (comparison): Control group, such as adults who received other forms of nicotine replacement therapy (NRT) or placebo.

O (outcome): Smoking abstinence rate, side effects of E-cigarettes, and withdrawal symptoms.

Inclusion criteria

The studies that were chosen employed E-cigarettes to help people over the age of 18 cut back or quit smoking. Review articles, RCTs, and cross-sectional studies were among the English-language publications. They discussed the intervention’s effectiveness, drawbacks, and withdrawal symptoms.

Exclusion criteria

Researches that solely employed alternative types of NRT or pharmacotherapy was disqualified, as was research on populations under 18 years old. Mini-reviews, animal research, expert comments, and articles from predatory journals on Beall’s list were omitted.

Data management and extraction

In accordance with the recommendations of the Cochrane Collaboration, three researchers conducted a thorough review of the literature. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria were used for the analysis of the chosen studies. Review articles included published RCTs and cross-sectional observations that assessed the effectiveness of E-cigarettes for smoking cessation/habit reduction. Data regarding the typical study features, such as the study’s kind, country, year of publication, and typical participant characteristics, such as participant age and gender, treatment effects, and side effects, were retrieved.

Study quality and bias risk assessment

Two reviewers independently assessed the study’s quality using a technique that was tailored to the study’s design. Using RoB 2, a tool developed by the Cochrane Collaboration, RCTs were evaluated for bias risk. Cross-sectional studies used the appraisal tool (AXIS). The Oxford Centre for Evidence-Based Medicine recommendation (OCEBM) tool was used to assess each study’s degree of evidence in the last phase of the evaluation process.

  Results Top

For the comprehensive analysis, three RCTs, three cross-sectional studies, and 25 review articles were examined. The total number of subjects evaluated across all investigations was 12,210. One face-to-face computer-assisted survey and two web-based longitudinal surveys made up the three cross-sectional investigations. One trial among the three RCTS was double-blinded. [Table 1] and [Table 2] list the specifics of the studies that were considered, including the study site, sample size, comparator, length, follow-up, inclusion and exclusion criteria, and major findings for each study.
Table 1: Characteristics of included RCTs

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Table 2: Characteristics of included cross-sectional studies

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E-cigarette effectiveness: According to Bullen et al.,[6] 21 out of 657 people quit smoking, while according to Caponnetto et al.,[7] 22 out of 300 participants quit smoking with the use of E-cigarettes with nicotine. Various research articles reported the rate of abstinence of smoking of the addicts. Overall, 50% reduction was shown by three studies in cigarette consumption on a daily basis.[6],[7],[8],[9] Study by Hajek et al.[10] showed 18% abstinence with E-cigarette consumption and 9.9% with other nicotine replacement therapies.

Two researchers independently completed a specific quality assessment instrument, the revised Cochrane risk of bias tool, to evaluate the risk of bias in the included studies. According to a study by Bullen et al.,[6] selection bias was possible due to the use of community newspapers for the selection procedure and the inability to blind participants receiving assistance, as indicated in [Table 3]. Caponnetto et al. also stated that such selection through newspapers could lead to selection bias.[6],[7] Due to the primary methodology used to record exposure, two of the investigations by Brown et al.[8] and Siegel et al.[9] showed self-reporting information bias. A cross-sectional study’s quality was evaluated using AXIS TOOL, as shown in [Table 4].
Table 3: Types of bias reported for randomized control trials

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Table 4: Quality assessment of cross-sectional studies using AXIS TOOL

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  Discussion Top

In order to replace cigarettes and lessen the harm caused by smoking, researchers working on tobacco control were always looking for a device that could deliver nicotine like a cigarette but without its harmful combustion products.[11] Nicotine and the endogenous neurotransmitter acetylcholine, which operates by activating nicotine cholinergic receptors (nAChRs), are structurally identical.[12] The ion channel opens when nicotine binds to the nAChR, enabling calcium or sodium ions to enter. This causes the receptor to become activated. Nicotine releases additional neurotransmitters, including dopamine, norepinephrine, acetylcholine, serotonin, beta-endorphin, and gamma-aminobutyric acid, mostly presynaptically.[13] These neurotransmitters have pharmacological actions that communicate pleasure, arousal, and stimulation, as well as anxiety reduction and mood stabilization. Additional nicotinic effects include an increase in metabolic rate and suppression of appetite.[12] Positive reinforcements, including mood enhancement and absence of withdrawal symptoms, comprise of nicotine addiction.[12]

The “smokeless nontobacco cigarette,” invented by Herbert A. Gilbert in the United States in 1963, featured a heating element that was powered by batteries. Without igniting, this element heated flavors without causing combustion (US Patent No. 3,200,819).[14],[15] In 1990, the tobacco manufacturer Philip Morris created a puff-activated electric smoking gadget. It was made up of a battery-powered circuit, a permanent heater, a liquid applicator, and a disposable delivery module. It also had a liquid aerosol-generating medium. They created a capillary aerosol generator in 1994 that pumped liquid into a heated tube to create an aerosol.[16]

The E-cigarette was created in 2003 and is an electronic spray cigarette that cannot be smoked and releases nicotine with no tar. As a result, tobacco’s main source of dangerous chemicals was cut out. One of its key benefits was the ability to smoke without the tar, hence lowering the risk of cancer and also to provide a similar feel of smoking experience. It didn’t carry a risk of fire too as there was no need to lit it.[17] Different nicotine concentration levels are commercialized: typically, 0–6 mg mL-1 (low), 12–16 mg mL-1 (medium), and 18–24 mg mL-1 (high).[18]

The E-cigarette as we know it today was created in 2003 by a Chinese chemist named Hon Lik. The patents for electronic cigarettes, which were initially sold in China in 2004, were owned by the Chinese business Ruyan. In 2007, E-cigarettes were introduced to the American market, and the internet was important in their marketing.[1] Acute nicotine poisoning is one of the main dangers of using electronic cigarettes.[3],[19][Table 5] lists the benefits, drawbacks, and negative effects of E-cigarettes. The usage of nicotine-containing E-cigarettes and quitting smoking had a favorable link, according to our systematic research. Both forms of E-cigarettes aid in reducing the number of cigarettes consumed, although nicotine-containing E-cigarettes are more effective at assisting smokers in quitting than nonnicotin e-containing ones. There was a constant observation across all studies, various study designs, and methods of abstinence analysis. Hence, the null hypothesis cannot be completely accepted. Statistically significant results were observed across all studies. Besides nicotine replacement, other factors help for cessation of smoking and for being synergistic to E-cigarettes containing nicotine for quitting.[19],[20] E-cigarettes prove to be satisfying for the users because they mimic routine smoking in terms of physical behaviors, addressing habitual cure responses and their similarity to the smoking experience. This comes with the fulfillment of pharmacological needs too. One of the qualitative study sites is user satisfaction by many nonpharmacological aspects.[21] Another study that described the use of nicotine-free inhalators specified the sensory and behavioral simulation of smoking and the effect of manipulation and handling to encourage the cessation of smoking.[22]
Table 5: The pros and cons of E-cigarettes

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E-cigarettes’ negative environmental effects include decreased indoor air quality, difficult component disposal, and troublesome production.[23] E-cigarette use causes vaporized droplets and particles to be emitted into the atmosphere. Users of E-cigarettes also exhale some nicotine vapor, which results in passive inhalation by nearby individuals and is cause for concern given the negative consequences on overall health.[24]

  Conclusion Top

Our systematic review evaluated the results of numerous trials on using E-cigarettes to quit smoking. Bullen et al.,[6] Caponnetto et al.,[10] and Hajek et al.[10] All found that when using e-cigarettes, smoking abstinence rates were 3%, 7%, and 18%, respectively.[7] Many aspects, such as the variety of items, the types of users, and the patterns of product consumption, were taken into account while synthesizing the analysis results, and these factors typically make it more difficult to understand the research. From the perspective of public health, the advantages of the devices for quitting smoking and reducing tobacco harm should be balanced against their safety and other issues. Additionally, these gadgets need to be examined on economic grounds.

  Limitation Top

More large-scale randomized trials are required in order to confirm and validate the findings of our investigation. E-cigarettes’ ingredients and safety concerns need to be thoroughly examined if they are to be utilized for quitting smoking or reducing the harm caused by tobacco.

Clinical relevance

Studies that examine nicotine and its toxicant delivery should employ standardized methodologies; their potential harm, user types, and usage patterns should be identified in order to facilitate the interpretation and comparability of the research findings.[25],[26] E-cigarettes, though not formally regulated, can assist smokers who are unable or unwilling to stop in their efforts to abstain or cut back on cigarette use.[27],[28] It is well known that tobacco dependency is a chronic condition that may need ongoing care. Using a harm-reduction strategy, evaluating the effectiveness and, especially, the safety of E-cigarettes with longer durations of use and among individuals who are less interested in complete abstinence from nicotine should be a priority.[29],[30]



Financial support and sponsorship


Conflicts of interest

The authors declare no conflicts of interest.

Author contributions

Dr. Anagha Shete: Concept, literature search, and manuscript writing; Dr. Arti Hajarnavis: Literature search and manuscript writing; Dr. Mrinal Shete: Analysis of studies; Dr. Pallavi Channe: Manuscript writing and editing; Dr. Ashwini Nerkar: Editing and compilation; Dr. Abhijeet Sande: Manuscript wiring and editing.

Ethical policy and institutional review board statement

Not Applicable.

Patient declaration of consent

Not applicable.

Data availability statement

Data were obtained from an internet search.


  References Top

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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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