Cigarette smoking is a cause of serious disease in smokers, including cardiovascular disease (CVD). The processes underpinning the development of CVD are well understood. These involve many cell types and cellular processes contributing to the development of atherosclerotic plaques in blood vessels, leading to impaired tissue oxygen supply and acute manifestations such as myocardial infarction and stroke. Cigarette smoke contains thousands of chemicals, some of which can be harmful to the cardiovascular system and may promote atherogenesis. In this narrative review, we assess the growing body of evidence concerning the potential cardiovascular health impact of next‑generation tobacco and nicotine product (NGP) use, including electronic vaping product (EVP), heated tobacco product (HTP) and oral nicotine pouch (ONP) use. Exclusive use of NGPs substantially reduces exposure to harmful toxicants compared with cigarette smoking. Regarding CVD risk, we determine that: (i) in vivo and in vitro modelling studies demonstrate the potential for NGPs to reduce CVD risk compared with cigarette smoking; (ii) switching to the exclusive use of these products leads to reductions in biomarkers of exposure to cardiovascular toxicants and favourable changes in CVD risk-related biomarkers of potential harm; (iii) population‑level data show that switching to the exclusive use of both EVPs and HTPs is associated with reduced risk of CVD and related comorbidities compared with continued smoking, though data for ONPs in this area are lacking; and (iv) regulators are increasingly using science‑based evidence when approving marketing authorisations and the use of consumer‑facing reduced exposure claims. Overall, supporting the complete displacement of cigarettes with the use of NGPs has the potential to reduce CVD risk and improve both individual and population health.

Smoking-related disease is related to inhalational toxicant exposure. Here, we assessed levels of 17 analytes, which have a potential link to smoking-related disease, in aerosol from four variants of the ElfBar Elfa vaping product compared with cigarette smoke levels or safety limits. Carbon monoxide, NNK and NNN, acrolein, benzo[a]pyrene, 1,3-butadiene, benzene, cadmium and arsenic were below detectable or quantifiable levels in all vaping product aerosols. For formaldehyde and acetaldehyde, these were between 99.6% and 99.9% lower than levels in 3R4F reference cigarette smoke depending on the variant assessed. For metals quantifiable in the aerosols, assumed potential exposure levels among users were all significantly lower than USP permissible daily exposure levels for inhalational medicines or below NIOSH-recommended exposure limits. Overall, toxicant exposure among smokers completely switching to Elfa vaping product use would be significantly reduced, or eliminated, compared with continued smoking. Further, metal exposure is likely not of toxicological concern.

Introduction Cigarette smoking is the leading cause of preventable death and disease and arises due to prolonged and repeated inhalational exposure to chemical toxicants found in cigarette smoke. Within this context, vaping products, also termed e‑cigarettes or electronic nicotine delivery systems, have been positioned by public health bodies as being substantially less harmful than combustible cigarettes. Furthermore, evidence also suggests that vaping products may be more effective in supporting smoking cessation than traditional support such as nicotine replacement therapy. The UK National Health Service "Swap to Stop" initiative operationalised a harm reduction approach to support smokers' use of vaping products in switching from cigarette smoking, by providing vaping starter kits via Stop Smoking Services (SSS). Objectives The aims of this study were to assess the provision of vaping products and provider-reported aggregate quit rates for vaping products compared with other forms of smoking cessation support, among UK SSS, using data obtained from Freedom of Information requests. Methods Questionnaires were sent to 43 local authorities in the UK and, of these, 31 (72.1%) responded. Two authorities (4.7%) withheld permission for the information they provided to be shared or reused for news/reporting. Consequently, responses from 29 (67.4%) local authorities were analysed. Results Vaping products are now provided to smokers by the majority (n = 26; 89.7%) of SSS providers, and this is predominantly through the provision of open systems. The majority of providers provide a variety of flavoured vaping products, including fruit, mint/menthol, and tobacco flavours, and among those providing flavour information, 78.9% of service providers (n = 15) reported that 'fruit' flavours were most popular or most frequently provided. Quit rates were variable across the different service providers, ranging from 43% to 77% for vaping products and from 35% to 81% for other forms of cessation support. Among those providers who reported quit rates for both vaping products and other forms of support, the average quit rates were 61.5% for vaping products and 56.2% for other forms of support (p = 0.04). Conclusions Overall, these findings support that vaping products may provide smoking cessation support to smokers that exceeds that of other forms of support and that flavoured vaping products are highly provided and utilised by UK SSS providers.

Nicotine pharmacokinetics and subjective effects are important factors in assessing the abuse liability of tobacco products such as electronic nicotine delivery systems (ENDS). In addition, an abuse liability determination is informative in assessing the ability of ENDS to support switching from cigarette smoking.

Reducing the harms associated with cigarette smoking is a global public health priority. Both the individual‑ and population‑level health impacts of smoking can be reduced by novel products which deliver nicotine, but the use of which decreases user exposure to the harmful chemical toxicants responsible for smoking‑related disease. Electronic vaping products (EVP) heat a flavoured liquid, most commonly containing nicotine, to generate an inhalable aerosol. Smokers who switch exclusively to using EVP reduce their exposure to the harmful toxicants found in cigarette smoke, and increasing evidence supports that EVP can help smokers quit smoking and support tobacco harm reduction (THR) efforts. However, concerns are being raised regarding the use of EVP among those for whom they are not intended, particularly youth, which could mitigate their THR potential. Some of this concern is attributed to the use of non‑tobacco flavours in EVP, and there have been many calls to ban the use of such flavours. The aim of this review is to examine the recent scientific literature concerning non‑tobacco flavours in EVP, focussing on the potential toxicological impact of these flavours, whether flavours affect abuse liability/dependence potential and whether they support switching away from cigarette smoking, unintended use of flavoured EVP, and the impact of existing bans and the effect of regulation. Overall, we find that non‑tobacco flavoured EVP are not of a greater risk to health and have no greater abuse liability than tobacco flavoured EVP. There is some evidence that flavoured EVP may support switching among adult smokers, while unintended use may be experimental and may not translate into long‑term use or act as a 'gateway' into smoking. Current flavour bans have been largely ineffective in modifying use behaviour and may have unintended consequences such as increasing smoking prevalence and promoting illicit trade. Overall, the population‑level THR benefit of flavoured EVP, in terms of reducing smoking rates, largely outweighs the risks associated with unintended use. Maintaining flavour diversity is an important consideration when putting in place regulatory frameworks that aim to maximise the switching benefit for adult smokers and improve overall population‑level public health.

Data from pre-clinical and clinical studies form part of an integrated assessment of the tobacco harm reduction (THR) potential of novel products that may act as cigarette alternatives for adult smokers. We report data from pre-clinical (emissions chemistry and in vitro toxicology) and clinical (nicotine pharmacokinetics and subjective effects) studies conducted with the iSENZIA™ heated herbal system (HHS; PULZE™ 2.0 device with iSENZIA™ sticks), which utilizes electronic heating of a tea-based substrate to generate an inhalable nicotine-containing aerosol. The aerosols from the iSENZIA™ HHS contained significantly lower levels, by up to 99.8%, of the nine World Health Organization Study Group on Tobacco Product Regulation (WHO TobReg) analytes compared with 1R6F reference cigarette smoke and elicited significantly lower in vitro cytotoxicity, genotoxicity, and mutagenicity responses. The clinical study demonstrated that the iSENZIA™ HHS delivers satisfactory levels of nicotine to users and has lower abuse liability than cigarettes. Overall, our data suggest that iSENZIA™ has the potential to offer substantially reduced toxicant exposure, as well as a reduction in toxicity, compared to cigarettes, while delivering satisfactory levels of nicotine. These findings support the THR potential of the iSENZIA™ HHS as a reduced-risk, acceptable alternative product for adult smokers.

Cigarette smoking is the leading preventable cause of death and disease. Prolonged and repeated inhalational exposure to the chemical toxicants found in cigarette smoke is a known cause of cardiovascular disease, chronic lung disease, and cancer. Novel nicotine products, including e‑cigarettes and tobacco‑free nicotine pouches, reduce exposure to toxicants among those who smoke and switch to their use, reducing the risk of smoking‑related disease. Implementation of national strategies to reduce smoking‑related death and disease increasingly acknowledges the support that novel nicotine products can give to smoking prevention efforts. However, for such strategies to be successful, and for countries to achieve their 'SmokeFree' ambitions, these products need to be widely accessible to consumers. In a recent paper, Aremu and Ogugua called for restrictions on access to electronic cigarettes (e‑cigarettes) or electronic nicotine delivery systems (ENDS). While prescription‑only regulatory models were advocated, these risk constraining accessibility to those who smoke and have been shown to cause increases in criminal activity, systemic violence, and health risks associated with the proliferation of unregulated nicotine products. Prescription‑only regulation should be avoided due to the potential for these significant unintended consequences, although there is a place for prescription products in co‑existence with products available through general consumer routes. Instead of banning or placing restrictions on purchasing, the use of reduced-risk nicotine products among unintended users, such as youth, can be mitigated through innovation and technology. This would ensure that access to reduced-risk products among those who smoke would best serve tobacco harm reduction efforts and population health.

Harms associated with the use of smoked tobacco products, including waterpipes, are due to inhalational exposure to toxicants either present in tobacco or formed during the process of combustion. We assessed levels of 37 toxicants in aerosol emissions from conventional waterpipe heated with different charcoals and also with a heat management device (HMD), from the IQOS heated tobacco product (HTP), and the ‘OOKA’ electronic waterpipe. We also utilised literature data on toxicant yields in 3R4F reference cigarette smoke. When taking use patterns into account, toxicant yields were substantially lower in conventional waterpipe aerosol compared with cigarette smoke. Toxicant yields in electronic waterpipe aerosol were substantially lower than those in conventional waterpipe aerosol, both on a per session basis and when taking typical use patterns into account. Numerous toxicants in conventional waterpipe aerosol were absent in electronic waterpipe aerosol. In summary, during typical use conventional waterpipe emits fewer, and lower levels of, a number of toxicants relative to combustible cigarette smoke. In addition, electronically heating shisha further reduces toxicant levels, and many toxicants are absent in OOKA electronic waterpipe aerosol. These findings have important implications concerning toxicant exposure among waterpipe users, and for understanding how to potentially reduce health risks associated with waterpipe use.

Chemical toxicants released into the environment during the use of tobacco and nicotine products potentially give rise to an elevated health risk among non-users. The aim of this study was to assess the levels of a wide range of chemical toxicants in the indoor air of an unventilated testing facility during various scenarios of tobacco and nicotine product use, including the use of conventional waterpipes, electronic vaping products (EVPs, also known as e-cigarettes), an electronic waterpipe which uses electrical heating of shisha tobacco instead of conventional charcoal heating, and combustible-cigarettes. In the one-occupant scenarios, increases in PM10 and PM2.5 were greatest during conventional waterpipe use, approximately 40% lower for OOKA electronic waterpipe use, and lowest for EVP use. An increase in the combustion by-product CO was greatest for conventional waterpipe use, and substantially lower for EVP and OOKA electronic waterpipe use, with the latter generating only a negligible amount of CO. The increase in formaldehyde levels was greatest for conventional waterpipe use, and substantially lower for OOKA electronic waterpipe use. In ten-occupant product use scenarios, increases in PM10 and PM2.5 were greatest for EVP use and slightly lower for OOKA electronic waterpipe use, lower during the cigarette smoking scenario, and lowest for the unattended conventional waterpipes scenario. Increases in CO and formaldehyde were highest for the conventional waterpipes scenario, substantially lower during cigarette smoking, and negligible for OOKA electronic waterpipe and EVP use. Increases in several other volatile organic compounds and some polycyclic aromatic hydrocarbons were mainly seen only during cigarette smoking and were negligible during the other product use scenarios. This pattern was similar for the tobacco-specific nitrosamines NNN, NNK, and NAT. These findings have important implications concerning the potential for secondhand toxicant exposure among waterpipe non-users, and for understanding how to potentially reduce health risks associated with such exposure. [Contrib. Tob. Nicotine Res. 34 (2025) 230–241]

Completely abstaining from cigarette smoking or fully switching to e-cigarette (EC) use may be beneficial for reducing the global burden of smoking-related diseases. This study aimed to identify and compare the top 10 prospective predictors of smokers switching away from smoking in the United States. Data from adult exclusive cigarette smokers at Wave 4 of the Population Assessment of Tobacco and Health (PATH) study, who were followed up at Wave 6, were analysed. An Xgboost-based machine learning (ML) approach with a nested cross-validation scheme was utilised to develop a multiclass predictive model to classify smokers' behavioural changes from W4 to W6, including smoking cessation, full and partial switching to EC, and cigarette non-switching. The SHapley Additive exPlanations (SHAP) algorithm was deployed to interpret the top 10 predictors of each switching behaviour. A total of 396 variables were selected to generate the four-class prediction model, which demonstrated a micro- and macro-average area under the receiver operating characteristics curve (ROC-AUC) of 0.91 and 0.81, respectively. The top three predictors of smoking cessation were prior regular EC use, age, and household rules about non-combusted tobacco. For full switching to EC use, the leading predictors were age, type of living space, and frequency of social media visits. For partial switching to EC use, the key predictors were daily cigarette consumption, the time from waking up to smoking the first cigarette, and living with tobacco users. ML is a promising technique for providing comprehensive insights into predicting smokers' behavioural changes. Public health interventions aimed at helping adults switch away from smoking should consider the predictors identified in this study.

Tobacco harm reduction (THR) refers to strategies designed to reduce the health risks associated with tobacco smoking but may involve continued use of nicotine and/or tobacco. Next -generation products (NGPs) are a THR alternative as they do not burn tobacco or produce smoke and deliver nicotine and have fewer and substantially lower levels of harmful chemicals compared to cigarettes. Tobacco -free nicotine pouches (TFNPs) are an emerging category of nicotine -containing oral products that do not combust or contain tobacco leaf. Similar to Swedish snus, TFNPs are placed between a user's lip and gum, and nicotine is absorbed through the oral mucosa rather than being inhaled. The aim of this scoping review was to systematically collate and evaluate published scientific evidence (cut-off of 31 May 2023) identified from bibliometric databases investigating the potential of TFNPs to contribute to THR. Overall, studies examining chemical constituents indicated that the use of TFNPs may result in lower exposure to toxicants than other tobacco or nicotine -containing products, both combustible and non-combustible. This reduction in toxicant exposure has been demonstrated by multiple human biomarker studies and in vitro toxicological assessments to translate to harm reduction potential in smokers switching to TFNPs. However, further study is warranted. At present, there is some evidence from human behavioral research that TFNPs can support either transitioning away from smoking or reducing cigarette consumption. Furthermore, TFNP use appears very much limited to current users of traditional tobacco products, and youth uptake has been limited. In conclusion, the findings of this review indicate that TFNPs have the potential to support THR efforts and may help inform evidence -based regulation.

ObjectiveThis study aimed to examine the association between e-cigarette (EC) use patterns and health-related symptoms (fatigue, pain, and emotional problems) as well as general quality of life (QoL).MethodsData were analyzed from 7,225 adults across Waves 1–6 of the US Population Assessment of Tobacco and Health (PATH) study. Current combustible cigarette (CC) or EC use patterns included dual CC/EC use, exclusive EC use, non-current use of CC or EC, and exclusive CC smoking. Multivariate linear mixed-effects models were used to investigate longitudinal associations between EC use patterns, and symptom burdens/QoL scores.ResultsThose who were not currently smoking or vaping reported the lowest fatigue, pain, and emotional problems, and the best QoL, among the four groups (all p < 0.001). Compared to exclusive CC smoking, exclusive EC use was associated with a significant decrease of 0.065 units in average fatigue (95% confidence interval [CI]: −0.121, −0.009), of 0.206 units in average pain (95% CI: −0.355, −0.058), and of 0.103 units in average QoL scores (95% CI: −0.155, −0.051), with emotional problems similar over time.ConclusionExclusive EC users had less health-related symptoms and better QoL than those who were exclusive CC smokers. This should be taken into account when assessing the harm reduction potential of ECs.

Heated tobacco products represent a novel category of tobacco products in which a tobacco consumable is heated to a temperature that releases nicotine from the tobacco leaf but not to a temperature sufficient to cause combustion. Heated tobacco products may therefore have the potential to be a less harmful alternative for adult smokers who would otherwise continue to smoke cigarettes, as their use should result in exposure to substantially fewer and lower levels of toxicants. This update represents a two-year extension to our previous narrative review, which covered peer-reviewed journal articles published up to August 31, 2021. The scientific evidence published between 2021 and 2023 continues to indicate that aerosols produced from heated tobacco products contain fewer and substantially lower levels of harmful and potentially harmful constituents and that these observed reductions consistently translate to reduced biological effects in both in vitro and in vivo toxicological studies. Biomarker and clinical data from studies in which product use is controlled within a clinical setting continue to suggest changes in levels of biomarkers of exposure, biomarkers of potential harm, and clinical endpoints indicating the potential for reduced harm with switching to exclusive use of heated tobacco products in adult smokers. Overall, the available peer-reviewed scientific evidence continues to indicate that heated tobacco products offer promise as a potentially less harmful alternative to cigarettes, and as such, the conclusions of our original narrative review remain valid.

Compared to cigarette smoke, heated tobacco product (HTP) aerosol contains significantly fewer and lower levels of harmful and potentially harmful constituents (HPHCs). However, the impact on environmental air is relatively unexplored. Therefore, this study compared levels of secondhand aerosol (SHA) constituents in air following glo HTP use with secondhand smoke (SHS) constituents following cigarette smoking in an environmental test chamber (ETC). Extracted ETC air samples following product use sessions were analyzed for 27 SHS/SHA constituents, including HPHCs. The use of glo HTPs resulted in significantly lower SHA HPHC levels in the ETC air relative to SHS HPHC levels from cigarette smoking. Some aerosol constituents (benzene, CO, formaldehyde, nicotine, respirable suspended particles, toluene, ethylbenzene, fine particulate matter, m- and p-cresol, o-cresol, pyridine, styrene, and ultraviolet particulate matter) were either below the limit of detection in ETC air or at significantly low levels following glo HTP use relative to cigarette smoking. Mean concentrations of the assessed constituents were at least 90 % lower following use of glo HTPs compared to smoking combustible cigarettes. These results suggest that glo HTP use would not contribute significantly to indoor air contamination and would reduce non-user exposure to HPHCs and other harmful constituents relative to combustible cigarettes. Such reductions in non-user exposure should be considered when assessing the tobacco harm reduction potential of glo HTPs.

The prevalence of electronically vaporized cannabidiol (CBD) use is rising in many countries. However, few regulatory frameworks exist for inhaled CBD, and this lack of oversight may not protect consumers from adverse consequences. We generated a representative map of several global consumer vaporized CBD markets by collating data concerning cannabinoid levels, including CBD and Δ9-tetrahydrocannabinol, from the scientific literature. In addition, we analyzed several CBD e-liquids obtained in the UK. E-liquid CBD concentrations varied markedly both within and between markets. E-liquid CBD concentration commonly differed from the labeled amount, in one case by >200%, and fell outside a ±10% tolerance. Other cannabinoids, including Δ9-tetrahydrocannabinol, were commonly found in e-liquids. In summary, CBD e-liquids vary markedly in terms of CBD and other cannabinoid content, diluents, and contaminants. Due to the relatively unregulated state of the CBD vaporizer and e-liquid marketplace, consumers may be subject to harm associated with vaporized CBD use.

Heated tobacco products (HTPs) are electronic devices that heat tobacco sticks to temperatures much lower than those which cause pyrolysis and combustion in cigarettes. While this electrical heating causes the formation of an inhalable aerosol which contains nicotine, the aerosol from HTPs contains significantly fewer and lower levels of the harmful and potentially harmful chemicals found in cigarette smoke. As a result, HTP use potentially conveys reduced risks to health compared to cigarette smoking. While this relative reduction in individual health risk is becoming clearer, what is less certain is the impact of HTPs on overall population‑level health, taking into account both the potential positive impact on adult smokers who completely switch to using HTPs and any unintended impacts such as use by tobacco non‑users and particularly by youth. The aim of this scoping review was to collate and evaluate the published scientific evidence to date, with a cut‑off of 1 January 2024, investigating the impact of HTPs on population‑level health. This evaluation suggests that HTP use is almost exclusively observed among those with a history of cigarette smoking, and there is a growing body of evidence for the ability of HTPs to provide support for adult smokers to transition away from cigarette smoking, in the absence of any significant "gateway" into tobacco use initiation. Many studies have reported a significant degree of dual use of cigarettes and HTPs, and efforts to assess the reasons for such patterns of use, whether these provide overall exposure reductions, and whether dual use acts as a bridge towards a complete transition away from cigarette smoking, requires further investigation. In addition, correction of the widespread and increasing misperceptions of HTPs among adult smokers is recommended to promote HTP uptake as a potentially less harmful alternative to smoking in this population.

Modeling the public health effects of e-cigarettes requires estimates of the likelihood that different individuals and population subgroups will start using e-cigarettes and subsequently transition to and from combustible cigarette use. To begin to generate input values for modeling efforts, this study assessed adults' behavioral intentions in relation to a disposable e-cigarette, "BIDI® Stick." An online questionnaire assessed intentions to try and use a BIDI® Stick regularly in 11 flavor variants among United States (U.S.) nationally representative samples of adult (21+ years) non-smokers (n = 2284), current smokers (n = 2391), former smokers (n = 2241), and young adult (21-24 years) non-smokers (n = 1140) of combustible cigarettes following exposure to product information and images. Current smokers rated their intentions to use a BIDI® Stick to partially or completely replace cigarettes. Positive intention to try a BIDI® Stick at least once was, for each flavor variant, highest among current smokers (22.4%-28.1%), lower among former smokers (6.0%-9.7%) and non-smokers (3.4%-5.2%), and lowest among never-smokers (1.0%-2.4%). Among current smokers, former smokers, and non-smokers, trial and regular use intentions were lowest among e-cigarette non-users and e-cigarette never-users. Approximately 23.6% of current smokers reported an intention to use a BIDI® Stick in at least one flavor to completely switch from cigarettes and/or to reduce cigarette consumption. Low trial and regular use intentions suggest that U.S. adults who do not currently smoke cigarettes and/or use e-cigarettes are unlikely to initiate use of the BIDI® Stick e-cigarette. Trial and regular use intentions are highest among adults who currently smoke cigarettes and/or use e-cigarettes. A moderate proportion of current smokers may try using a BIDI® Stick e-cigarette as a partial or complete replacement for combustible cigarettes.

Nicotine delivery and subjective effects are determinants of the ability of potentially less harmful tobacco products such as heated tobacco products (HTPs) to support adult smokers in switching away from cigarettes, and therefore to support tobacco harm reduction. This open-label, randomised, crossover, clinical study in 24 healthy adult smokers study assessed nicotine pharmacokinetics and subjective effects of the Pulze Heated Tobacco System (HTS; Pulze HTP device and three iD stick variants—Intense American Blend, Regular American Blend and Regular Menthol) compared with subjects’ usual brand cigarettes (UBC). Cmax and AUCt were highest for UBC and significantly lower for each Pulze HTS variant. Cmax and AUCt were significantly higher for Intense American Blend compared with Regular American Blend, while AUCt was significantly higher for Intense American Blend compared with Regular Menthol. Median Tmax was lowest (i.e., nicotine delivery was fastest) for subjects’ usual brand cigarettes and similar across the iD stick variants, although no between-product differences were statistically significant. All study products reduced urges to smoke; this effect was greatest for cigarettes although this was not statistically significant. Product evaluation scores for each Pulze HTS variant in the domains of ‘satisfaction’, ‘psychological reward’ and ‘relief’ were similar, and lower than those for UBC. These data demonstrate that the Pulze HTS effectively delivers nicotine and generates positive subjective effects, including satisfaction and reduced urge to smoke. This supports the conclusion that the Pulze HTS may be an acceptable alternative to cigarettes for adult smokers while having a lower abuse liability than cigarettes.

Abstract Background Ecigarette (EC) use is rising, and evidence increasingly supports that ECs are helpful in smoking cessation. However, evidence concerning the longterm health effects of conventional cigarette smokers who switch to using ECs, and changes in healthrelated symptoms and quality of life (QoL), are lacking. Objective To examine the effects of switching from smoking to using ECs on healthrelated symptoms (fatigue, pain, and emotional problems) and general QoL. Methods We analysed data from 7,122 adult respondents in the U.S. Population Assessment of Tobacco and Health (PATH) study. These were exclusive cigarette smokers at Wave 1 and were followed up at any of Waves 2 to 5. At the followup waves, respondents were categorised into four groups based on their switching behaviours: (1) full switching (switching to exclusive EC use); (2) partial switching (switching to dual use of cigarettes and ECs); (3) quitting (not beginning EC use); and (4) nonswitching (exclusive cigarette smoking). Linear mixedeffects models controlling for age, sex, race, level of education and time were used to calculate adjusted mean differences (aMD) with 95% confidence intervals (CI) in general QoL and related factors between nonswitching and switching groups. Results Compared to nonswitching, full switching was significantly associated with less fatigue (aMD − 0.092; CI -0.167 to -0.017; P = 0.016), less emotional problems (aMD − 0.089; CI -0.175 to -0.002; P = 0.044), better QoL (aMD − 0.124; CI -0.193 to -0.056; P < 0.001), but similar pain (aMD − 0.156; CI -0.351 to 0.038; P = 0.108). No significant differences were observed between partial switching and nonswitching groups for fatigue, pain, emotional problems, or QoL (P > 0.05 in all cases). Those who quitted smoking and did not begin EC use reported the lowest fatigue, pain, and emotional problems, and the best QoL, among the four groups (all P < 0.001). Conclusions Smokers who quitted smoking or fully switched to using ECs had less healthrelated symptoms and better QoL than those who continued smoking. This impact on QoL should be taken into account when assessing the harm reduction potential of ECs, and the development of practices to help smokers switch and improve their QoL also needs to be considered.