Table 2

Sample characteristics and objectives of included articles (* indicates study was included in original 2016 review)

Study ID (country)Sample size and study populationStudy aimMain findings on flavours’ impact
Amato et al (USA)*42 n=9301
Adults (18+ years)
Tobacco users and non-users
Investigate patterns of e-cigarettes’ use in order to establish a standard definition of e-cigarette current use prevalence for the purpose of population surveillance.Current e-cigarette users cited flavours as a reason for use more often than past users.
Audrain-McGovern et al (USA)30 n=32
Young adults (18–30 years)
Current cigarette smokers and had ever used an e-cigarette
Determine whether flavouring enhances the subjective rewarding value, relative reinforcing value and absolute reinforcing value of an e-cigarette with nicotine compared with an unflavoured e-cigarette with nicotine.E-cigarette flavouring enhanced the rewarding and reinforcing value of e-cigarettes with nicotine compared with unflavoured e-cigarettes with nicotine.
Barnes et al (USA)31 n=36
Adults (18+ years)
Current cigarette smokers naive to e-cigarettes
Examine e-cigarettes’ abuse liability compared with conventional tobacco cigarettes that varied in e-cigarette flavour and modified-risk message.Cherry flavour increased abuse liability relative to unflavoured e-cigarettes (ie, increased the degree to which e-cigarettes led to physical/psychological dependence).
Berg (USA)*46 n=1567
Young adults (18–34 years)
E-cigarette users, non-users; cigarette users, non-users
Compare (1) e-cigarette never, current and former users; (2) never, current and former traditional cigarette smokers in relation to e-cigarette use characteristics, flavours preferred and reasons for use and (3) reasons for discontinued use among former e-cigarette users across never, current and former smokers.Flavours were frequently indicated as reason for use across smoking and non-smoking e-cigarette users
Bold et al (USA)53 n=340
Youth (middle school and high school students)
Ever e-cigarette users
Investigate whether certain reasons for trying e-cigarettes would predict continued use over time.Good flavours were highly endorsed by youth as a reason for trying e-cigarettes; in univariate models, endorsing good flavours as a reason for trying e-cigarettes predicted continued e-cigarette use and e-cigarette frequency, but was no longer a significant predictor after adjusting for other covariates including cigarette smoking status.
Brozek et al (Poland)56 n=46
Adults (18–35 years)
E-cigarette users
Assess prevalence of e-cigarette and tobacco cigarette use; to compare the patterns of smoking and to assess the attitudes and motivations for e-cigarette use.More than one-fourth of e-cigarette users started using e-cigarettes because of the unique flavours.
Buckell et al (USA)66 n=2031
Adults (18–64 years)
Current cigarette smokers or recent quitters
Estimate preferences for flavours in cigarettes and e-cigarettes while controlling for other attributes of both products, and study how these preferences vary with individual characteristics.Among e-cigarette flavours, adult smokers preferred tobacco flavour over fruit/sweet and menthol flavours; younger adult smokers, those with a higher education and those with a recent quit attempt prefer all flavours of e-cigarettes compared with tobacco cigarettes.
Camenga et al (USA)75 n=189
Youth (14–18 years) and young adults (18–24 years)
Lifetime cigarette smokers and ever e-cigarette users
Examine the prevalence and predictors of current and former smokers’ use of e-cigarettes for smoking cessation.Preference for using a combination of two or more e-cigarette flavours mixed together was associated with increased odds of using e-cigarettes for smoking cessation, relative to e-cigarette users without a preferred flavour.
Chen et al (USA)54 n=18 392
Youth (11–18 years)
Non-smokers
Explore association between e-cigarette use and smoking susceptibility among non-smoking youth.Flavoured e-cigarette use was associated with increased smoking susceptibility among non-smoking youth, particularly among females and those not susceptible to tobacco marketing.
Chen (USA)35 n=4645
Young adults (18–34 years)
Current cigarette smokers at Wave 1
Examine differences in smoking reduction and cessation among young adult smokers who did not use e-cigarettes, who used e-cigarettes with tobacco and menthol/mint flavours and who used e-cigarettes with one or multiple non-tobacco and non-menthol flavours.Compared with non-e-cigarette users, users of non-tobacco/menthol e-cigarette flavours were more likely to have reduced or quit smoking cigarettes in the past year; current e-cigarette users highly endorsed using e-cigarettes because of appealing flavours, with those endorsing this reason for use more than twice as likely to have reduced or quit smoking in the past year than e-cigarette users who did not endorse this reason for use.
Clarke and Lusher (UK)25 n=256
Youth (16–19 years)
Tobacco users and non-users
Investigate factors that lead to willingness to try e-cigarettes among UK youth.Youth reported a preference for non-tobacco-flavoured e-cigarettes, regardless of smoking status; youth with a more positive prototype of smokers were more willing to try flavoured e-cigarettes, while youth with a more negative prototype of e-cigarette users were less willing to try flavoured e-cigarettes.
Coleman et al (USA)43 n=3373
Adults (18+ years)
Current e-cigarette users
Examine patterns of current e-cigarette use among daily and non-daily adult users.Appealing flavours were highly cited as a reason for e-cigarette use, particularly among never smokers; more frequent e-cigarette users (daily vs moderate or infrequent) were more likely to initiate with a non-tobacco-flavoured e-cigarette.
Cooper et al (USA)28 n=3704
Youth (grades 6, 8 and 10)
Tobacco users and non-users
Evaluate harm perceptions and perceived addictiveness of e-cigarettes among youth.Youth who were ever or current e-cigarette users had higher odds of reporting flavoured e-cigarettes as less harmful than non-e-cigarette users.
Czoli et al (Canada)*39 n=915
Youth and young adults (16–24 years) and adults (25+ years)
Users and non-users (youth and young adults) and users (adults)
Determine the effect of distinct attributes of e-cigarettes (flavours, nicotine content, health warnings, price) and attribute levels on consumer choice.Flavours in e-cigarettes significantly predicted lower perceptions of product harm and ability to help someone quit smoking.
Dai and Hao (USA)29 n=21 491
Youth (middle and high school students)
Tobacco users and non-users
Examine the (1) association between flavoured e-cigarette use and intention to initiate cigarette smoking among never-smoking youth, (2) association between flavoured e-cigarette use and intention to quit tobacco use in the next 12 months among current youth smokers and (3) association between flavoured e-cigarette use and youth perception of the danger of tobacco.Compared with not using e-cigarettes, flavoured e-cigarette use was associated lower perceived harm of tobacco, higher intention to initiate cigarette use among never smoking youth and lower quit intentions among current smoking youth.
Elkalmi et al (Malaysia)36 n=277
Primarily adults (18+ years) but 7.2% of sample was 17 years or younger
Tobacco users and non-users
Determine the prevalence of current e-cigarette use and identify sociodemographic factors, motivators, attitudes and perceptions that are associated with current e-cigarette use.The majority of respondents who had tried e-cigarettes reported that the variety of flavours contributed to more enjoyment of the product compared with conventional cigarettes.
Etter (France,
Belgium and other countries)*37
n=81
Adults (18+ years)
Current e-cigarette users
Assess usage patterns of e-cigarettes, reasons for use and users' opinions of these products.Adult e-cigarette users reported flavours as being the most positive feature of the product.
Etter (France, USA, Switzerland, UK and other countries)72 n=1685
Adults (18+ years)
Current e-cigarette users
Describe personal characteristics of vapers, their utilisation patterns, any modifications of the devices and compare users of prefilled cartridges, refillable tanks, and modified models for their patterns of use, reasons for use, satisfaction and perceived effects on smoking.Tobacco flavour was reported to be the most preferred e-cigarette flavour among current users, particularly among those who had recently started vaping; most respondents reported that flavours helped them to either quit smoking or reduce their smoking consumption.
Farsalinos et al (online survey in 10 languages)*71 n=4618
Adults (18+ years)
E-cigarette users
Examine the patterns and perceptions of flavouring use in e-cigarettes among dedicated users.E-cigarette users who were former smokers were more likely to prefer fruit and sweet flavours compared with current smokers. E-cigarette users reported that the variability of e-cigarette flavours is an important factor in reducing or quitting cigarette smoking and a greater number of flavours used was associated with smoking abstinence.
Farsalinos et al (online survey in 10 languages)*58 n=19 441
Adults (18+ years)
E-cigarette users
Assess the characteristics and experiences of a large, worldwide sample of e-cigarette users and examine the differences between those who partially and completely substituted smoking with e-cigarette use.The variability of flavours was cited as one of the reasons for initiating e-cigarette use, though it was not a primary reason.
Ford et al (UK)*26 n=1205
Youth (11–16 years)
Tobacco users and non-users
Examine adolescents’ awareness of e-cigarette marketing and investigate the impact of e-cigarette flavour descriptors on perceptions of product harm and user image.Fruit and sweet flavours were perceived as more likely to be tried by young never smokers than adult smokers trying to quit. The perceived harmfulness of e-cigarettes was moderated by product flavours.
Goldenson et al (USA)32 n=20
Young adults (19–34 years)
Current e-cigarette users
Assess whether sweet flavourings and nicotine affect e-cigarette appeal; sweet flavourings increase perceived sweetness; nicotine increases throat hit; and perceived sweetness and throat hit are associated with appeal.Sweet-flavoured e-cigarette solutions increased appeal (including liking, willingness to use again and amount willing to pay) and perceived sweetness ratings.
Gubner et al (USA)45 n=168
Adults (18+ years)
Weekly or daily e-cigarette users
Examine e-cigarette use by individuals in treatment for substance abuse.A large proportion of daily and weekly e-cigarette users reported using e-cigarettes because they have good flavours; daily e-cigarette users were more likely to use more types of flavours compared with weekly users.
Harrell et al (USA)50 n=3907 youth, n=5482 young adults and n=6051 adults
Youth (12–17 years), young adults (18–29 years) and adults (30+ years)
Tobacco users and non-users
Investigate whether the use of flavoured e-cigarettes varies between youth, young adults and adults.Initiation with and current use of flavoured e-cigarettes were higher among youth and young adults compared with older adults, and citing flavour availability as a reason for use was higher among youth current users relative to young adults and older adults.
Harrell et al (USA)69 n=143 youth and n=1325 young adults
Youth (12–17 years) and young adults (18–29 years)
Current tobacco product users
Determine the potential for reductions in the prevalence of young people’s e-cigarette and tobacco use if characterising flavours were not present.The large majority of youth and young adult current tobacco users reported use of flavoured e-cigarettes, and about three-fourths of flavoured e-cigarette users reported they would no longer use the product if it was not flavoured.
Kim et al (USA)33 n=31
Adults (18+ years)
Current e-cigarette users
Examine the extent to which the perception of sweet and other flavours is associated with liking and disliking of flavoured e-cigarettes.Flavours influenced hedonic ratings of e-cigarettes, such that, in general, sweetness and coolness were positively associated with liking while bitterness and harshness were negatively associated with liking of e-cigarettes.
Kinouani et al (France)57 n=1086
University students (18+ years; more than 90% 18–24 years)
Ever e-cigarette users
Describe the relationship between e-cigarette use and tobacco smoking and describe reasons for experimenting with e-cigarettes.The third most cited reason for trying e-cigarettes was because of attractive flavours, behind reasons of curiosity and offered to try by someone.
Kong et al (USA)*62 n=1157
Youth and young adults
E-cigarette users
Assess reasons for e-cigarette experimentation and discontinuation and examine whether these reasons differed by school level (MS, HS, college) and cigarette smoking status.Availability of flavours was a primary reason for experimentation with e-cigarettes and appealing flavours were particularly important to high school students.
Krishnan-Sarin et al (USA)*64 n=4780
Youth
(middle school and high school students)
Tobacco users and non-users
Examine e-cigarette awareness, use patterns, susceptibility to future use, preferences, product components used, and sources of marketing and access among youth.Use and preference for sweet e-cigarette flavours were high among adolescents regardless of cigarette smoking status.
Lee et al (USA)60 n=1185
Young adults (18–25 years)
Tobacco users and non-users
Investigate the characteristics of potential and current e-cigarette users based on four different levels of use acceptability and determinants that promote e-cigarette acceptability.A higher preference for the availability of flavours in e-cigarettes was associated with experimentation and current use of e-cigarettes among college students.
Lee et al (South Korea)40 n=6656
Youth (13–18 years)
Ever e-cigarette users
Determine the relation between frequency of e-cigarette use and the frequency and intensity of conventional cigarette smoking; and identify the association between reasons for e-cigarette use and frequency of use.Nearly 1 in 10 youth cited good flavours as the main reason for using e-cigarettes, though this reason ranked behind five others, including curiosity and potentially being less harmful.
Litt et al (USA)70 n=88
Adults (18–55 years)
Cigarette smokers
Examine the influence of flavouring on the smoking and vaping behaviour of cigarette smokers asked to adopt e-cigarettes for 6 weeks.Cigarette smoking frequency was most reduced in participants assigned to menthol-flavoured e-cigarettes, while it was least reduced in those assigned to cherry and chocolate flavours; participants assigned to tobacco-flavoured e-cigarettes had the highest rates of vaping, while those assigned to chocolate had the lowest rates of vaping.
Maglalang et al (USA)47 n=56
Asian American and Pacific Islander young adults (18–25 years)
Current e-cigarette users
Characterise e-cigarette use and risk perceptions among Asian American and Pacific Islander young adults in California.Fruit and candy/sweet flavours were most preferred by current e-cigarette uses, though citing flavours as a reason for using e-cigarettes was reported by a low percentage of respondents, behind a variety of other reasons.
Morean et al (USA)68 n=396 adolescents and n=590 adults
Adolescents (high school students) and adults (18+ years)
Past-month e-cigarette users
Examine differences in adolescents’ and adults’ preferences for e-liquid flavours and whether their preferences or the total number of flavours preferred were associated with number of days of e-cigarette use in the past month.Compared with adults, adolescents were more likely to prefer e-liquid flavours such as fruit, candy/dessert and vanilla, while adults were more likely to prefer tobacco, menthol/mint, coffee and spice flavours.
Among adolescents (though not adults), preferences for particular e-liquid flavours (ie, fruit, dessert or alcohol flavoured) and the total number of flavours preferred were associated with more frequent e-cigarette use.
Nonnemaker et al (USA)*34 n=765
Adults (18+ years)
Current or former smokers
Examines how e-cigarette attributes influence willingness to pay for e-cigarettes.Losing flavours significantly reduced the price participants are willing to pay for e-cigarettes, though this relationship was not found for dual users of cigarettes and e-cigarettes.
Patel et al (USA)48 n=2448
Adults (18+ years)
Current e-cigarette users
Assess reasons for e-cigarette use among current e-cigarette users.Reasons for e-cigarette use among current adult users varied by sociodemographic and user characteristics; notably, flavourings were more likely to be cited as a reason for use among younger age groups (ages 18–24, 25–34 and 35–54 years).
Pepper et al (USA)*52 n=228
Youth (11–19 years), males
Tobacco users and non-users
Sought to understand awareness of and willingness to try e-cigarettes among adolescent males.Flavoured e-cigarettes did not increase male adolescents’ willingness to try e-cigarettes compared with plain varieties.
Pepper et al (USA)*59 n=3878
Adults (18+ years)
Tobacco users and non-users
Explore reasons for starting and then stopping e-cigarettes use and examine differences in discontinuation by reason for trying among population-based sample of US adults.Few adult e-cigarette users reported starting e-cigarette use because of the available flavours.
Pepper et al (USA)27 n=1125
Youth (13–17 years)
Tobacco users and non-users
Examine the impact of flavour on interest in trying e-cigarettes and harm beliefs.Adolescents were more interested in trying menthol, candy or fruit-flavoured e-cigarettes than tobacco or alcohol flavours; belief that these particular flavours were less harmful than tobacco or alcohol flavours partly mediated this relationship.
Pesko et al (USA)67 n=1020
Adults (18+ years)
Current cigarette smokers
Determine the preferences and relative importance placed on e-cigarette warning labels, flavour regulation and prices.Restriction of flavour availability in e-cigarettes to tobacco and menthol was associated with a significant reduction in e-cigarette selection, particularly among young adults compared with older adults.
Russell et al (USA)61 n=20 836
Adults (18+ years)
Frequent e-cigarette users
Examine flavour preferences of frequent e-cigarette users.Adults are increasingly initiating e-cigarette use with non-tobacco flavours, particularly fruit and dessert flavours; never smoker e-cigarette users were more likely to initiate with and currently use fruit/fruit beverage-flavoured e-cigarettes compared with switchers, dual users and former smoker e-cigarette users.
Rutten et al (USA)49 n=582
Adults (18+ years)
Current dual users of cigarettes and e-cigarettes
Assess attitudes, beliefs and behaviours relating to e-cigarette use among current cigarette smokers.Dual users of cigarettes and e-cigarettes ranked appealing flavours relatively low on the list of reasons for using e-cigarettes; no differences in smoking quit intentions or reduction in the use of cigarettes was observed for those reporting using e-cigarettes because of flavours compared with those not reporting using e-cigarettes because of the flavours.
Shang et al (USA)63 n=515
Youth (14–17 years)
Tobacco users and non-users
Understand how different attributes (flavours, health warnings, device types) influence youth’s decisions to choose e-cigarettes.Among youth ever and never e-cigarette users, fruit/sweet/beverage flavours increased the probability that a youth chose an e-cigarette product.
Shiffman et al (USA)*38 n=216 (youth) and n=432 (adults)
Youth (13–17 years)
Adults (19– 80 years)
Non-users (youth) and users (adult)
Compare e-cigarettes interest between nonsmoking teens and adult smoker, across flavours and assess differences in flavour preferences among adult smokers based on e-cigarettes use history.The interest of non-smoking teens in trying flavoured e-cigarettes was very low, and interest was not influenced by flavour descriptors. Though adult smokers’ interest was also modest, their interest was significantly higher than that of non-smoking teens for each flavour.
Shiplo et al (Canada)*51 n=1095
Youth and young adults (16–24 years)
Adults (25+ years)
Non-smokers and smokers (youth and young adults) and smokers (adults)
Examines e-cigarette ever and current use, types of products used and reasons for use.Use of flavoured e-cigarettes varies by smoking status, with smokers being more likely to try flavours than non-smokers. A common reason for e-cigarette use is for the taste.
Spears et al (USA)44 n=550
Adults (18+ years)
Current e-cigarette users
Examine reasons for e-cigarette use and related risk perceptions among individuals with and without mental health conditions.Compared with former smokers without mental health conditions, former smokers with mental health conditions placed higher importance on appealing flavours as a reason for e-cigarette.
Tackett et al (USA)*74 n=215
Adults (18+ years)
E-cigarette users
Estimate e-cigarettes preference, e-cigarettes use behaviours, perceived harm and health beliefs of various smoking cessation medications, nicotine replacement therapies and nicotine/tobacco products, and smoking history and current biochemically verified smoking status.Most e-cigarette users reported a preference for vaping non-traditional flavours. Those who reported vaping non-tobacco and non-menthol flavours were more likely to have quit smoking compared with those who vaped traditional (tobacco/menthol) flavours.
Tsai et al (USA)41 n=4049
Youth (grades 6–12)
Ever e-cigarette users
Assess self-reported reasons for e-cigarette use among middle school and high school student e-cigarette users.One of the primary reasons for e-cigarette use by middle school and high school students was the availability of flavours, particularly among high school students.
Vasiljevic et al (UK)*55 n=471
Youth (11–16 years)
Non-e-cigarette users
Assess the impact on appeal of tobacco smoking after exposure to advertisements for e-cigarettes with and without candy-like flavours.Flavoured, compared with non-flavoured, e-cigarette advertisements elicited greater interest in buying and trying e-cigarettes.
Weaver et al (USA)73 n=858
Adults (18+ years)
Current cigarette smokers
Assess the effect of ‘real world’ e-cigarette use on population quit rates of adult smokers, accounting for frequency of use, device type, e-liquid flavour and reasons for use.Compared with non-e-cigarette users, users of menthol/wintergreen/mint or other non-tobacco/menthol flavour e-cigarettes (eg, fruit, dessert, spice) were more likely to report a quit attempt, but users of other non-tobacco/menthol e-cigarette flavours had significantly lower odds of quitting smoking than non-users of e-cigarettes in the past year.
Yingst et al (USA and other countries)*65 n=421 (87% in USA; 13% outside USA)
Adults (18+ years)
E-cigarette users
Examine the frequency with which e-cigarette users transition between device types and identify device characteristics and user preferences that may influence such transitions.Most e-cigarette users began use with a device shaped like a cigarette (first-generation devices) and transitioned to a larger advanced generation device with a more powerful battery and a wider choice of liquid flavours. Advanced generation device e-cigarette users report the variety of flavours as being important characteristic of e-cigarettes.