Nicotine - Dual & Poly Use
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Dual and poly use of nicotine products can take many forms among a variety of products. Most often discussed are vapes and combustible cigarettes, but other forms of dual/poly use do exist. Of great interest are people who are trying to quit smoking by vaping. As in every form of quit smoking methods, vaping works for some, and not for others. Some people start out vaping while continuing to smoke, gradually working toward vaping more and smoking less, and ultimately quitting smoking. But that does not happen for everyone. Some continue to dual use for months/years - often with a reduction of cigarettes smoked per day, and sadly, some go back to solely smoking.
Retractions of Papers Mentioning Dual/Poly Use
- Chronic Obstructive Pulmonary Disease (COPD) and asthma were both more prevalent in dual smokers.
Comments On Papers About Dual/Poly Use
2024: Comments RE: Dual and poly-nicotine and tobacco use among adolescents in the United States from 2011 to 2022
- "Overall, Zhang et al. improperly conclude that there is a true uptick in dual- and poly-use of nicotine and tobacco in NYTS, but did not attribute any of their findings to a well-documented methodological artifact in NYTS 2021 which renders the findings inconclusive, as (in the words of official NYTS publications) 'differences between estimates might be due to changes in methodology, actual behavior, or both.' ” (Selya)
- Referring To: Zhang, B., Bannon, O., Chen, D. T., & Filippidis, F. T. (2024). Dual and poly-nicotine and tobacco use among adolescents in the United States from 2011 to 2022. Addictive Behaviors, 152, 107970. https://doi.org/10.1016/j.addbeh.2024.107970
- One of the studies used in the meta-analysis has been retracted.
- "The study provides zero evidence on any risk associated with e-cigarette use, whether absolute risk or in comparison with smoking. The question that was supposed to be addressed in this metanalysis CANNOT be examined with the studies included in their analysis." (Farsalinos)
- See Also: "The methods look impressive, but the devil is in the dirty details buried in the nearly 100 pages supplemental material. The authors have done an admirable job collecting studies and organizing them, but the conclusions reached are untenable, and unsupportable at least for now." (Cummings)
- Inaccurate and misleading meta-analysis of E-cigarettes and population-based diseases: "We demonstrate that the meta-analysis by Glantz et al. had three principal deficits that were avoidable: (1) mixing unjustified and incomprehensible disease outcomes, such as erectile dysfunction with fatal CVDs and influenza with COPD; (2) using survey datasets containing no temporal information about smoking/vaping initiation and disease diagnosis; (3) using longitudinal studies that didn’t account for changes in vaping and smoking during follow-up waves. The meta-analysis by Glantz et al. is misleading and inaccurate. The deficits are only apparent to investigators thoroughly experienced with the data from the source studies. We conclude that Glantz et al. failed to meet basic criteria for the quality of source studies; the results of their meta-analysis are invalid." (Rodu, Plurphanswat, and Rodu)
- Comparing smoking-related disease rates from e-cigarette use with those from tobacco cigarette use: a reanalysis of a recently-published study: "The claim in the original meta-analysis that the studies had a low risk of bias is demonstrably incorrect, and even the biased data suggests that switching to e-cigarettes may reduce disease risk similarly to quitting. Biases may also explain the somewhat higher risk observed in those who smoked and vaped than in those smoking exclusively. Very limited unbiased data found no significant effect of vaping on the diseases considered. Though more good studies are urgently needed, the conclusions of Glantz et al. are not supported by the currently available evidence." (Lee, Farsalinos)
- Observational studies of exposure to tobacco and nicotine products: Best practices for maximizing statistical precision and accuracy: The case study discussed below (Glantz et al., 2024) includes two cautionary examples which selected case-control designs and subsequently reported that CC use was not associated with increased risk of cardiovascular harm (with former CC use being associated with reduced risk in one study). In other words, they attributed the entirety of risk associated with tobacco product use to EC use. (Cohen, Cook)
- When meta-analysis misleads: the need for methodological integrity in e-cigarette research: Together, these findings suggest that many of the alarming conclusions drawn were overstated. This is especially true when the analyses fail to disentangle the effects of vaping from those of smoking, a mistake that continues to plague much of the current literature. (Polosa, Geraci, Adebisi)
- The Updated Meta-Analysis of E-Cigs & Health Outcomes: Still Critically Flawed: A highly-criticized meta-analysis of e-cigs &health outcomes was just updated. Not only does it still perpetuate critical flaws in the underlying studies, but it's interpreted with double-standards. (Selya)
- Referring to: Glantz SA, Nguyen N, Oliveira da Silva AL. Population-Based Disease Odds for E-Cigarettes and Dual Use versus Cigarettes. NEJM Evid. 2024 Mar;3(3):EVIDoa2300229. Epub 2024 Feb 27. PMID: 38411454. doi: 10.1056/EVIDoa2300229
Addiction/Dependence
- Among current users, dependence on e‐cigarettes was significantly lower than dependence on cigarettes, in within‐subjects comparisons among dual users of both e‐cigarettes and cigarettes, and in separate groups of e‐cigarette users and cigarette smokers, and among both daily and non‐daily users of each product.
- Among former users, residual symptoms were significantly lower for e‐cigarettes than cigarettes, both among former dual users and among users of one product.
- The highest level of e‐cigarette dependence was among e‐cigarette users who had stopped smoking.
- Use of e‐cigarettes appears to be consistently associated with lower nicotine dependence than cigarette smoking.
- Results: Our analytic sample included 5538 (91.5 %) cigarette only, 399 (6.7 %) ENDS only, and 108 (1.8 %) dual users. There was no difference in CD between cigarette only and dual users. ENDS only users' ED (2.11, SE = 0.05) was higher than dual users' ED (1.67, SE = 0.04) (p < 0.05). Dual users' mean ED (1.70, SE = 0.09) was significantly lower than their CD (3.03, SE = 0.11) (p < 0.001), and ENDS only users' ED (2.34, SE = 0.05) was significantly lower than cigarette only users' CD (2.94, SE = 0.02) (p < 0.001).
- Conclusion: While there was no difference in CD between dual and cigarette only users, dual users' ED was lower than that for ENDS only users. ENDS appeared to produce less dependence than cigarettes among dual users.
- The ten-item Penn State Dependence Index (PSDI) suggested greater dependence on smoking than vaping
- The most common reasons for vaping were to reduce smoking (79%), enjoyment of flavors (78%), and ability to vape where smoking is not allowed (73%). Perceptions of less harm to others (69%) or to self were the next most common (65%). Fewer than half used ECs to reduce stress, for affordability, or because others used them.
- PDF Version
Adverse Childhood Experiences (ACE)
- Purpose: Sexual and gender minority (SGM) young adults report disproportionately higher rates of tobacco and nicotine product use. This study assessed the role of adverse childhood experiences (ACEs) in nicotine and tobacco product use among SGM young adults. Methods: A cross-sectional survey was administered to 11,694 college students (ages 18-29 years) between 2017 and 2018 in California, Minnesota, and Texas. Results: For every additional ACE reported, the odds of cigarette, e-cigarette, and dual use increased for all students, with significantly higher past 30-day cigarette use among ACE-exposed SGM students. Conclusion: ACEs are an important contributing factor to tobacco-related disparities facing SGM groups.
Guidance for Healthcare Practitioners
- This guide can support professionals working across behavioral health, public health, and tobacco control systems in addressing dual use among the patients and individuals they serve. Dual refers to the regular use of both combustible cigarettes and e-cigarettes. This resource provides practical guidance to help providers and program leaders better understand, assess, and treat dual use. Research on dual use remains in its early stages, and ongoing studies may lead to changes in some of the findings presented in this report.
Harm Reduction
- The predominant dual-use pattern was characterized by regular e-cigarette and intermittent cigarette use. Findings demonstrate the short-term harm reduction potential of this dual-use pattern in Black and Latino smokers and suggest that the greatest benefit, aside from cessation of both products, is achieved by higher substitution of e-cigarettes for cigarettes. Findings need confirmation in a larger sample with longer follow-up in dual users with greater variability in the rate of substitution.
- Subjects switching to e-cigarettes had significantly lower levels (29 %–95 %) of urinary BoEs after 5 days. Nicotine equivalents declined by 25 %–40 %.
- Dual users who substituted half of their self-reported daily cigarette consumption with e-cigarettes experienced 7 %–38 % reductions, but had increases (1 %–20 %) in nicotine equivalents.
- Blood nicotine biomarker levels were lower in the cessation (75 %–96 %) and e-cigarette use groups (11 %–83 %); dual users had no significant reductions.
- All groups experienced significant decreases in exhaled CO (27 %–89 %). Exhaled NO increases (46 %–63 %) were observed in the cessation and e-cigarette use groups; dual users had minimal changes.
- By Day 5, all groups had greater reductions in smoking urge compared to cessation. However, reductions were larger in the dual use group.
- No serious adverse events were observed.
- PDF Version
Initiation
- "Compared to those who first tried cigarettes, students who first tried e-cigarettes were less likely to be current smokers (RR=0.19 [CI: 0.11 – 0.31]) or dual users..."
Pregnancy
- The birthweight of infants born to EC users is similar to that of non‐smokers, and significantly greater than cigarette smokers. Dual users of both cigarettes and EC have a birthweight similar to that of smokers.
Prevalence
- "How dual use is defined and operationalized varies between studies. Some rely on any current use of both products or use within the past 30-day period, while others require daily or near-daily use of each. This inconsistency complicates efforts to monitor trends, assess risk, and design targeted interventions. For example, a person who smokes once a week and vapes daily is often categorized identically to someone who smokes and vapes multiple times a day. In addition, people differ in their reasons for dual use: some may be actively trying to quit smoking, while others use e-cigarettes to circumvent smoking bans or in settings where smoking is socially unacceptable. These variations in motivation, frequency, and context can skew our understanding of dual use and its impacts, leading to ambiguous or contradictory findings."
- In England, vaping prevalence has increased rapidly among adults who smoke since 2021, which was when disposable e-cigarettes started to become popular. Since 2016, patterns of dual use have shifted away from more frequent smoking towards more frequent vaping. This may be the result of increasing prevalence of dual use among younger adults, who are more likely than older dual users to smoke non-daily and vape daily.
- Smoking, vaping and dual use were substantially higher among those with a history of MHC, especially multiple MHC, and experiencing past month distress than those not having a history of MHC or experiencing past month distress respectively. Analysis used descriptive epidemiology and causation cannot be determined.
- Nearly two thirds of current vapers are ex-smokers (64.6%), and the proportion continues to grow, while the proportion who also smoke (known as dual users) has fallen to 30.5% in 2021.
- Fewer than 1% of never smokers are current vapers (amounting to 4.9% of vapers).
- As in previous years the main reason given by ex-smokers for vaping is to help them quit (36%) then to prevent relapse (20%).
- The main reason given by current smokers for vaping is to cut down (26%) then to help them quit (17%) and to prevent relapse (14%).
- Nearly a third of smokers incorrectly believe vaping is more or equally as harmful as smoking (32% compared to 34% in 2020).
- In the mature snus market of Norway, the magnitude of dual use of cigarettes and snus is relatively small. Dual users consume fewer cigarettes, and a higher proportion portray themselves as smoke-free in the future than do exclusive cigarette smokers.
Regulatory Restrictions
- Hypothetical regulations resulted in reported intentions to reduce EC (e-cigarette) use and increase CC (combustible cigarette) use; the greatest impact was found for restrictions regarding e-liquid nicotine content, followed by flavor
- This work provides preliminary evidence that restrictive regulations regarding key EC characteristics may increase intentions to increase CC use among young adult dual EC and CC users.
- PDF Version
Smoking Cessation/Abstinence/Reduction/Switching
- Another finding of practical importance is that dual use was associated with stopping smoking later and in those who did not manage to stop smoking, it was linked with a substantial reduction in smoking. This was not just a reduction in cigarette consumption, which on its own may not convey much health benefit if the remaining cigarettes are smoked with more intensity, but an objectively validated reduction in smoke intake which would be accompanied by a reduction in health risks.
- Expert reaction to this study
- Results: "Noticing fruit flavors (AOR = 1.67 and 1.28) and fruit images (AOR = 1.53 and 1.21) was positively associated with having any e-cigarette product appeal and switching interest. Noticing price promotions (AOR = 1.23) was positively associated with product appeal. In contrast, noticing nicotine warnings (AOR = 0.74 and 0.86), smoker-targeted claims (AOR = 0.78 and 0.89), and tobacco flavors (AOR = 0.92 and 0.90) was negatively associated with product appeal and switching interest."
- Rates of complete switching away from cigarettes increased over time, while dependence and frequency of respiratory symptoms were lower than Baseline over time.
- Our findings indicate that inclusion of varenicline in a cessation programme for adults who smoke and use e-cigarettes with an intention to quit smoking could result in smoking abstinence without serious adverse events. In the absence of evidence from other smoking cessation methods, it could be useful to suggest the use of varenicline in cessation programmes specifically designed to help dual users stop smoking.
- Conclusion: "Adolescents used e-cigarettes mainly for experimental and/or recreational purposes, with no intention of progression to daily smoking. Although the design of this study is not longitudinal and caution must be exercised, from our cross-sectional observational study data, it appears that the proportion of “non-vapers and non-smokers” tended to increase. “Smokers” tended to progress to the dual use of vaping and smoked tobacco, with the likely intention to reduce or quit smoking."
- 3 in 10 of U.S. adult dual users used e-cigarettes to help quit smoking while 2 in 10 of U.S. adult dual users used e-cigarettes to stealth vape. Compared to daily dual users, predominant smokers [adjusted odds ratio (AOR) = 0.61, 95% CI = 0.23, 0.62] were less likely to use e-cigarettes to help quit smoking whereas predominant vapers (AOR = 1.80, 95% CI = 1.04, 3.13) were more likely to use e-cigarettes to help quit smoking and less likely to use e-cigarettes to stealth vape (AOR = 0.30, 95% CI = 0.10, 0.89).
- Nearly 60% of the analytical sample reached the 50% smoking reduction threshold at week 3; the percentage of individuals in each trajectory class who reached the 50% outcome ranged from 13% (the maintainer group) to 89% (moderate reducers), with 61% success among the rapid reducers and 56% among slow reducers.
- A targeted self-help intervention with high potential for dissemination could be efficacious in promoting smoking cessation among dual users of combustible cigarettes and e-cigarettes.
- PDF Version
- Dual use declined over time as complete switching increased. By 12 months, 43.2% reported dual using, and 51.2% reported switching away from cigarettes. Among dual users, approximately 60% reduced their cigarette consumption substantially (by ≥ 50%); average reductions in cigarette consumption were > 80%. Only a small minority (3%-10%) substantially increased cigarette consumption.
2021: Switching away from Cigarettes across 12 Months among Adult Smokers Purchasing the JUUL System
- Respondents (N = 17,986) were 55.0% male, 78.3% white, mean age = 32.65 years (SD = 10.81), mean baseline cigarettes/day = 11.10 (SD = 8.16). The proportion self-reporting switching increased over time: one-month (27.2%[3718/13,650]), 2-month (36.4%[4926/13,533]), 3-month (41.0%[5434/13,257]), 6-month (46.6%[5411/11,621]), 9-month (49.4%[6017/12,186]), and 12-month (51.2%[6106/11,919]); 33.1% reported switching at both 9-month and 12-month follow-ups. In prospective analyses, smokers with lower cigarette dependence, shorter smoking history, lower cigarette consumption, more frequent JUUL use, greater satisfaction from initial JUUL use, and higher JUUL dependence were significantly more likely to switch.
2021: (poster) LONGITUDINAL STUDY OF DUAL USE OF COMBUSTIBLE CIGARETTES AND THE JUUL® SYSTEM IN ADULT CURRENT SMOKERS AT 12 MONTHS
- Dual use is often a transitional stage characterized by reductions in CC consumption followed by switching completely away from CCs.
- Findings indicate that e-cigarette flavor use among dual users who attempt to quit smoking may be related to e-cigarette use frequency overall, which may indicate a mechanism underlying findings for e-cigarette use and smoking cessation.
- Dual use of e-cigarettes is associated with a greater reduction in cigarette consumption than dual use of OTC NRT. It may discourage a small proportion of users from making a quit attempt compared with dual OTC NRT use but it does not appear to undermine use of evidence-based cessation aids.
- In England, dual use of e-cigarettes is not associated with reduced overall quit rates compared with exclusive smoking or dual use of NRT. However, dual use of e-cigarettes is associated with a slightly higher quit attempt rate than exclusive smoking but lower than dual use of NRT.
- Compared with those with other perceptions of e‐cigarette harm, dual users who perceived e‐cigarettes as less harmful than cigarettes were more likely to become exclusive e‐cigarette users 1 year later.
- PDF Version
- The most prevalent motivation for using e-cigarettes was to reduce tobacco smoking 48%, followed by quitting smoking 39.2%, and to use e-cigarettes in places where tobacco smoking was prohibited 10.2%.
- Of the e-cigarette users, 61.1% remained abstinent from tobacco (while 23.1% and 26.0% of tobacco-only smokers and dual users achieved tobacco abstinence).
- PDF Version
- To the extent that dual users substantially lower the number of cigarettes, they will reduce health risks from smoking. However, from a medical point of view, exclusive vaping is preferable to dual use;
- Differences between dual users and switchers center around variables proximal to the vaping behavior and its experienced effects rather than hinging on more general vaping-related beliefs and attitudes.
- After e-cig initiation, dual users decreased tobacco consumption by 82% and were low-to-moderately cigarette dependent.
- The two groups (dual users and switchers) reported mostly using a flavor other than tobacco.
- PDF Version
- Among men who reported life-time experience with both products, a large majority had initiated their tobacco use with cigarettes.
- The average number of cigarettes smoked weekly was lower among dual users compared with current smokers who were former snus users or had never used snus.
- During the period 2003–15 in Norway, which has a mature snus market, even though smoking has declined and the relative size of the category of never-smokers among male users of snus has increased, the majority of snus users are still former or current smokers.
- E-cigarettes have grown popular. The most common pattern is dual use with conventional cigarettes. Dual use has raised concerns that it might delay quitting of cigarette smoking. This study examined the relationship between long-term use of e-cigarettes and smoking cessation in a 2-year period.
- Dual use of e-cigarettes and cigarettes was not associated with a lower smoking cessation rate.
- Among those making a quit attempt, use of e-cigarettes as a cessation aid surpassed that of FDA-approved pharmacotherapy.
- Long-term use of e-cigarettes was associated with a higher rate of quitting smoking.
- PDF Version
- Follow-up data were available for 236 e-smokers, 491 tobacco smokers, and 232 dual smokers (overall response rate 70.8%). All e-smokers were tobacco ex-smokers. At 12 months, 61.9% of the e-smokers were still abstinent from tobacco smoking; 20.6% of the tobacco smokers and 22.0% of the dual smokers achieved tobacco abstinence. Adjusting for potential confounders, tobacco smoking abstinence or cessation remained significantly more likely among e-smokers...
- PDF Version
Weight
- “Conclusion: Within the study limitations, EC use may help smokers attenuate cigarette consumption or remain abstinent, as well as reduce their post-cessation weight increase. The potential role of the e-vapour category for harm minimization in relation to tobacco and/or food abuse requires confirmation from larger prospective studies. Moreover, the observed lack of post-cessation weight gain in those who reduced substantially cigarette consumption by switching to ECs (i.e., dual users) is an interesting finding and calls for further research investigating the role of nicotine in weight control. Meanwhile, these preliminary findings should be communicated to smokers and particularly to weight-conscious smokers intending to quit.
- By combining substantial reduction of smoking with prevention of post-cessation weight gain, EC-based interventions may promote an overall improvement in quality of life. Considering that the negative effects of weight increase could overshadow the health benefits of smoking abstinence, it is important to stimulate more research in this area.”
Websites, Articles, Op-Eds, Blogs, Letters, Testimony
- With wider acceptance that e-cigarettes are a viable harm-reduction method among people who smoke, the scientific battleground has retreated to "dual use." A recent exchange captures this well.
- Arielle Selya, PhD
- Another way to look at dual use, harm reduction, and support for people who smoke.
- Skip’s Corner
- For example, long-acting nicotine patches can be used with shorter-acting nicotine gum OR lozenge to control withdrawal symptoms and the urge to smoke.
- CDC
2025: Dual use of cigarettes and vapes can reduce risks of smoking and help smokers quit, study finds
- "A new major study from Queen Mary University of London has found that smokers who use both cigarettes and e-cigarettes at the same time—known as dual use—are reducing their intake of harmful chemicals and are also more likely to eventually quit smoking than those who continue to smoke only. This challenges common fears about dual use."
- Medical Xpress
- “There’s lots of disagreement as to whether dual use is a good thing or a bad thing,” said Matthew Carpenter, Ph.D., co-leader of the Cancer Prevention and Control research program at MUSC Hollings Cancer Center and the Flora McLeod Edwards Distinguished Endowed Chair in Cancer Research at MUSC. “You can make an argument for either, and you can find evidence either way that dual use could be a good thing or a bad thing – it really depends on what you're comparing it to,” he said.
- MUSC Medical University of South Carolina
- Dual use, referring to people who smoke and vape concurrently, is a phenomenon often cited by opponents of vaping to discredit its harm reduction impact. To their claim that switching is not quitting, they add that dual use simply extends people’s addiction to nicotine, doesn’t help them quit smoking, and may even be worse for health than smoking alone.
- Proponents of tobacco harm reduction counter that dual use is typically a transition period to much safer products, but that even long-term dual use has its benefits.
- Filter
- Testimony in Netherlands pertaining to a potential flavour / flavor ban. This document responds to the proposed Decree of the State Secretary for Health, Welfare and Sport on the regulation of e-cigarette flavours in the Netherlands.
- Signed by 24 experts from around the world
- Covers 12 key points
- Sets conflicting objectives and takes a “war on drugs” approach to nicotine.
- Adopts false and misleading claims about the risks of e-cigarettes.
- Draws on irrelevant information about an outbreak of lung injuries in North America.
- Misunderstands “dual-use”.
- Asserts a “gateway effect” but there is more likely to be a diversion away from smoking.
- Takes a simplistic approach to youth risk behaviours and fails to demonstrate benefits to adolescent public health.
- Ignores perverse consequences of prohibition, even though these are foreseeable.
- Fails to show benefits for adolescents or address concerns it may cause harm to young people.
- Ignores the harmful effects of a vaping flavour ban on adults.
- Creates regulatory protection for the cigarette trade.
- Violates important regulatory principles, including those underpinning the European Union internal market.
- Proposes an illiberal policy and fails to recognise a major global public health opportunity.
- Acknowledgement: We confirm that signatories report no conflicts with respect to FCTC Article 5.3 and no financial conflicts of interest with respect to tobacco or e-cigarette companies under the International Committee of Medical Journal Editors (ICJME) reporting standard.
Policy Papers
- Taxpayers Protection Alliance