In this survey of 2477 respondents aged 16 years or older, 397 (16.0%) individuals identified themselves as current vapers, the majority of whom were users of multiple substances (68.5%)—any combination of nicotine-based e-liquids, nicotine-free e-liquids or cannabinoid-based products. In the 12 months preceding the survey, these current vapers had experienced a number of symptoms previously reported in EVALI cases, ranging from 3.8% for bloody sputum or haemoptysis (15 respondents) up to 30.5% for cough (121 respondents). The aggregate number of healthcare attendances for all symptoms was 385, ranging from 2 attendances for bloody sputum up to 130 attendances for SOB. UK-based vaping surveys have typically tracked user ‘harm perception’ of vaping but this is the first known UK-based survey to qualify specific symptoms amongst current vapers and to quantify the healthcare burden associated with these symptoms.^1,2 Excessive harm perception of e-cigarettes amongst current cigarette smokers has traditionally been listed as a barrier to smoking cessation by the Office for Health Improvement and Disparities (OHID) in England.^12,13

Although a recent comprehensive review on the toxicology of e-liquids outlined multiple mechanisms of toxicity, OHID reports the evidence supporting a harmful effect of legal e-liquids on adults is largely insufficient or inconclusive and concludes that the associated health risks are likely only a fraction of those of smoking.^13,14 However, OHID also concedes that the effectiveness of heated tobacco products in smoking cessation remains uncertain. Given vaping is a relatively new practice it also difficult to comment on the long-term effects of vaping—this is particularly concerning given the Action on Smoking and Health in Youth survey recently reported the prevalence of current vaping in British 11–17 year olds had more than doubled to 7.0% in 2022 from 3.3% in 2021.¹⁵ Despite our survey being restricted to respondents aged 16 years or older we detected a considerably lower median age in substance used cohorts that were unlikely to be for smoking cessation purposes—48 years for nicotine-based e-liquids only vs. 29–38 years for all other cohorts. This was consistent with a lower prevalence of concurrent smoking within the nicotine-based e-liquids only cohort—45.7% vs. 45.0–93.8% for all other cohorts.

The three most common symptoms reported by current vapers were SOB, cough and lethargy. Whilst these are not pathognomonic symptoms, they were amongst the most frequently reported symptoms in previous US EVALI cases series.^7–9 It should be noted that within this survey, symptomatic respondents more commonly reported no change in the frequency of their symptoms since they began vaping for each of the 10 complaints. Furthermore, symptomatic respondents more commonly reported their symptoms being less rather than more frequent since they began vaping for SOB, cough, fever/high temperature, chills and bloody sputum. This was contradicted by the relatively high number of symptomatic respondents reporting new symptoms in the 12 months prior to the survey: SOB (46.2%), fever/high temperature (44.1%), chills (39.6%), cough (34.7%) and bloody sputum (26.7%). It was unclear why these responses relating to symptom frequency were discordant although a degree of recall bias is possible given the retrospective nature of the survey. Symptomatic respondents more commonly reported their symptoms as more rather than less frequent since they began vaping for lethargy/fatigue, nausea, vomiting and palpitations. Respondents reporting nausea and vomiting within this survey were generally over-represented by current vapers using cannabinoid-based products (45.9% of respondents with nausea, 47.8% of respondents with vomiting vs. baseline prevalence of 34.0% within survey). The majority of previous US EVALI cases involved the use of products containing THC—it is possible that the ongoing use of these products contributes to a higher incidence of gastrointestinal symptoms. Symptomatic respondents with palpitations were over-represented by current vapers exclusively using nicotine-based e-liquids (36.7% of respondents with palpitations vs. baseline prevalence of 23.2% within survey). Irrespective of route of administration, nicotine is known to increase heart rate via activation of the sympathetic nervous system with tachyarrhythmias a recognized complication.¹⁶ The legal nicotine content of e-cigarettes in the UK is 2% (20 mg/ml), higher than the estimated nicotine content of a standard cigarette (10–15 mg) of which 10% (1–1.5 mg) is usually absorbed.¹⁷ Furthermore, the smoking toolkit study demonstrated that the percentage of ex-smokers and smokers using e-cigarettes with 2% nicotine content or above (informally/illegally sourced) has increased from 1.7% and 5.1%, respectively, in 2016, up to 26.3% and 25.2% in 2022. It is conceivable that vapers using e-cigarettes with a higher nicotine content would be more likely to report palpitations for the reasons outlined above, as evidenced by the higher incidence of palpitations within this survey.

This survey was able to compare the prevalence of symptoms and number of healthcare presentations amongst current vapers in relation to ‘substance used’ cohorts. Current vapers of cannabinoid-based products with nicotine-free e-liquids were significantly more likely to report SOB, chest pain, fever/high temperature, chills and nausea. These users were also significantly more likely to seek healthcare for SOB and cough. Current vapers of cannabinoid-based products alone were significantly more likely to report SOB, chills and nausea and significantly more likely to seek healthcare for SOB. Respondents vaping cannabinoid-based products with nicotine-based e-liquids were significantly more likely to report chills. It is unclear why the cohort of vapers using all three substances (cannabinoid-based products, nicotine-based e-liquids and nicotine-free e-liquids) were not significantly more likely to report symptoms or seek healthcare however statistical testing was limited by the number of symptomatic respondents within the survey. Cohorts involving the use of cannabinoid-based products (alone or in combination) accounted for the highest number of attendances per healthcare attendee for nine out of the 10 symptoms; the exception being palpitations whereby users of nicotine-based e-liquids re-attended most frequently. The increased healthcare burden associated with cannabinoid-based products is likely a reflection of the unregulated nature of these products and the informal means by which users acquire them.³ It should be noted that current vapers of nicotine-free e-liquids were significantly more likely to report cough. One possible explanation is the young median age of these users (32.5 years)—it would be fair to assume that these users have had limited prior exposure to inhaled products. Current vapers of nicotine-based e-liquids and nicotine-free e-liquids were significantly less likely to report chest pain and less likely to seek healthcare for SOB and cough. Concurrent smoking within this cohort was the third lowest at 61.3% and an argument could be made that smoking cessation had improved symptoms, although similar trends were not observed within the nicotine-based e-liquids only cohort where concurrent smoking was the second lowest at 45.7%. When concurrent smoking was compared with exclusive vaping, cough was also significantly more prevalent amongst the concurrent smoking group (P < 0.01) however there was no significant difference with any of the other symptoms. This finding was consistent with a recent prospective study in the USA that demonstrated e-cigarette use in young adults was associated with respiratory symptoms irrespective of combustible cannabis and cigarette exposure, suggestive of the likely pathological effect of vaping independent of smoking.¹⁸ In our survey, cough was also more common in the cohort using nicotine-free e-liquids only, despite this group having the lowest rate of concurrent smoking (45.0%).

Symptomatic current vapers did not report a diagnosis of vaping-related illness for any of the healthcare presentations. Clinicians reportedly diagnosed RTIs, asthma/COPD or anxiety/panic attacks most commonly. As stated in the introduction, we have previously suggested that under-recognition and underreporting of EVALI internationally has likely resulted in lower case numbers of EVALI being reported outside of the USA.⁵ If this were the case, it would hold true that milder forms of vaping-related illness not meeting EVALI case criteria were also under-recognized, as suggested by the results of this survey.

Two previous UK-based publications have also concluded that clinician understanding of e-cigarettes remains suboptimal.^19,20 The Medicines and Healthcare products Regulation Agency in the UK recommends documenting e-cigarette or vaping device use as part of routine clinical practice, including frequency of use and substances used.²¹ However the British Thoracic Society’s National Smoking Cessation Audit 2021 found that only 6% of the 14 579 medical records reviewed contained information on vaping status.²² Accurate documentation of vaping or e-cigarette use is likely to lead to an improved understanding of the risks associated with vaping and confer benefits at both an individual and population level.²³

This research was subject to a number of limitations. The number of current vapers was relatively small resulting in fewer symptomatic respondents. As a result, statistical testing was restricted to the symptoms with 30 or more symptomatic vapers or 30 or more healthcare attendees (arbitrary ‘non-small’ sample size). As previously stated, the possibility of recall bias should be acknowledged given the retrospective nature of the survey. Finally, the survey did not ask ‘never’ and ‘previous’ vapers about the presence of symptoms therefore we could not make comparisons between the health of these respondents and current vapers; data were also not collected to determine other potential causes of the symptoms reported.