The age distribution for the UnderageJUUL subreddit is shown in Table 1. We counted a Reddit user in the general categories of less than 18 years or over 21 years, if the user stated in their threads or comments that they were under 18 or greater than 21 years old; 67 out of 844 (7.9%) UnderageJuul Redditors reported their age in the threads or comments.

We analyzed the subreddit preferences of all UnderageJuul Redditors. Among 844 UnderageJuul Redditors, 437 had also posted threads on the JUUL subreddit, which is the general discussion subreddit of JUUL products. The other 9 subreddits in the top 10 most popular with UnderageJUUL users were as follows: AskReddit (general Q&A, n=250), trees (marijuana, n=145), FortNiteBR (computer game, n=125), Drugs (n=123), pics (interesting pictures sharing, n=106), mildlyinteresting (general discussion, n=103), Showerthoughts (general discussion, n=102), teenagers (n=96), and funny (general discussion, n=86). We also provided the full list of subreddit interests in Multimedia Appendix 1.

We extracted 74 explicitly mentioned locations from the thread text. We summarized the mentioned locations and labeled them on Google Maps API, as shown on Figure 1. Among these locations, New York City and the Bay Area were the most mentioned areas. The detailed location count summary to each state can be found in Multimedia Appendix 2.

Next, we analyzed the approaches that were used to purchase JUUL by UnderageJuul users. By examining purchase requests and completed transactions in detail, we observed that there were 7 approaches that users employed to buy JUUL. These approaches are listed as follows:

Finally, we analyzed the flavors mentioned in the subreddit. There were 7 flavors from JUUL’s official website: mango, cucumber, mint, menthol, tobacco, fruit medley, and crème brûlée. We found that mango was the most mentioned flavor (n=38). Mint (n=22) and cucumber (n=21) were popular as well. The other 4 flavors, including fruit medley (n=6), crème brûlée (n=6), menthol (n=5), and tobacco (n=4), were not frequently mentioned.

In this study, we obtained the following main findings pertaining to demographics, methods of access, product characteristics, and use patterns of underage JUUL use. First, most threads or comments did not mention specific age, but ages ranged from 13 years to greater than 21 years in those that did. Second, mango, mint, and cucumber were the most popular among the 7 flavors from JUUL’s official website, and 336 subreddit UnderageJuul threads mentioned 7 discreet approaches to circumvent relevant legal regulations to get JUUL products, the most common of which was purchasing JUUL from other Reddit users (n=181). Third, almost half of the UnderageJuul users (389/844, 46.1%) also participated in discussions on the main JUUL subreddit and were seeking information across multiple Reddit forums. Finally, most (64/74, 86%) posters were from large metropolitan areas defined by the United States Office of Management and Budget [26]. These findings could help public health community and policy makers understand the current situation of underage JUUL use and provide them with insights on how to leverage social media for timely surveillance of emerging public health issues.

We found that only a small number of Redditors (67/844, 7.9%) reported their ages in a subreddit for underage JUUL users. After the FDA’s deeming rule, the minimum age to purchase e-cigarettes for all states in the United States is 18 years. If we set 18 years as the legal age threshold, 60% (40/67) of the Reddit users in Table 1 were underage JUUL users. Alabama, Alaska, and Utah have set 19 years as the legal age to buy e-cigarettes and vaping products. In California, Hawaii, Maine, Oregon, and New Jersey, the legal age is 21 years. There are also more than 330 states, cities, and counties that have raised the minimum age to 21 years. Thus, if we raise the legal age threshold to 21 years, 94% (63/67) of the Reddit users in Table 1 were underaged. As purchasing JUUL is not legal for underage Redditors, they were more likely to avoid discussing their ages or to report fake ages. Therefore, the age distribution we obtained from explicit mentions was biased. The actual age distribution could probably be even younger. Given subreddit UnderageJuul was an active forum oriented for underage JUUL users before it was banned, it is still a valuable data source for analyzing underage JUUL users and their usage patterns.

We found that there was an overlap of users between the JUUL subreddit and the UnderageJuul subreddit. Specifically, 46.1% (389/844) of UnderageJuul Redditors also participated in discussions on the JUUL subreddit. Given the fact that most of the JUUL-related discussions on Reddit are on the JUUL subreddit, it is reasonable to infer that even though the UnderageJuul subreddit was removed by Reddit, underage JUUL users still have other forums for discussing JUUL with other users. This finding indicates that public health interventions, such as social media campaigns, are needed to target underage e-cigarette users.

We also analyzed the interests of the UnderageJuul users. These interests were extracted from their Reddit profiles and indicated some of these users contributed to teenager-related topics on Reddit. This finding suggests that some UnderageJuul Redditors have a high probability to be real underage JUUL users, though most of them did not report their ages in the UnderageJuul subreddit.

This study found that most of the geographic locations mentioned in threads were from large cities in the United States. In particular, New York City and the Bay Area were the most mentioned areas. The location information was collected via user-posted JUUL Web-based vendors, shipping information, or simply inquiring about local JUUL stores. As many of the inquiries were about local vape or smoke shops without age verification, the findings suggest that social media could be a useful tool for federal and state regulatory authorities to use for assessing whether vape or smoke shops are meeting regulatory requirements pertaining to e-cigarette use, especially in large cities.

Our study found that mango, mint, and cucumber flavors were more popular than other JUUL flavors among youth and young adult Reddit users, which is similar to previous findings that mint, cucumber, and mango JUUL flavors were most mentioned in tweets [9]. From previous research about e-cigarette flavors [27], strawberry was the most mentioned fruit flavor for other e-cigarette products. Instead, mango or cucumber flavors were hardly mentioned. However, these 2 flavors turned out to be successful for JUUL, suggesting that more effort is needed to understand if some flavors are more appealing to underage e-cigarette users or if a product’s appeal is more important than a specific flavor availability. Tobacco flavor was widely mentioned in previous e-cigarette studies, but it was not popular in youth and young adults. One possible reason is that many of the underage JUUL users are nonsmokers, so the tobacco flavor is not appealing. The finding suggests that more research is needed for studying the impact of e-cigarette flavors on underage e-cigarette use.

Our study found that users of the UnderageJuul subreddit used different discreet approaches to circumvent relevant legal regulations to get JUUL. Some of these approaches (eg, purchase via eBay) are also reported in previous studies [9,16]. This study and the findings contribute to the literature by providing a detailed category dictionary for purchase approaches. On the basis of the well-established coding method, we developed 7 different categories for purchase approaches [24]. Our finding suggests that more regulation is needed to make sure that online or offline e-cigarette vendors strictly perform age verification and that legal e-cigarette users cannot provide ways of buying e-cigarettes to teenagers. In addition, parents may need to assess their teenagers’ access to credit cards and IDs of legal adults.

Note that JUUL has established their age policy and required the minimum purchase age on their official website to be 21 years since August 2018. The JUUL product replacement request is also subject to the age verification. However, the identified 7 categories of workaround purchase approaches still work. Ordering the products or replacements from the official website just needs a fake ID or a preverified account. Not to mention those approaches provided by third parties such as eBay or PayPal. As the prevalence of teen JUUL use [28] and the high conversion rate from e-cigarette users to smokers [29], we call for more research and effort on this domain and take action to monitor and control these approaches.

Although this Web-based forum facilitates the JUUL transactions under the table, we still observed Redditors who tried to persuade teenagers not to start the vaping habit or not to get addicted to nicotine, especially for those who were extremely young, such as 13- or 14-year-old teens. This phenomenon represented the goodwill of the community. These comments also create additional questions about the specific population using UnderageJuul. Were those who made comments recommending against the use of ENDS products adults or youth? If they were adults, who are they, and why are they contributing to this particular subreddit? We cannot answer these questions given the limited information on this online forum, but we believe it is a promising future research direction to study the community and environment of underage e-cigarette users.

This study has some limitations. First, we could not verify if the self-reported ages in the data were real or fake owing to the anonymity of Reddit users. Most of these ages were general, and these Reddit users often stated that they were underage or legal adults. However, as this subreddit was specifically created for discussion of underage JUUL users, we think the mentioned ages were fairly reliable. In addition, the number of mentioned ages was relatively small compared with the number of the subreddit users, and only a small number of users shared an age. Second, the location distribution in this study faces a similar limitation as the age distribution, because we cannot get the exact addresses of Redditors from Reddit. In this study, we did not distinguish buyers’ locations and sellers’ locations, as we focused on the locations related to JUUL transactions. Third, the number of different flavors mentioned in the data was relatively small, but we can see their relative popularity among these Redditors. Fourth, we could not determine whether some messages were posted by e-cigarette store owners, others who have an interest in selling e-cigarettes, or even robots because the demographics of Reddit users were not available.

Despite the above limitations, the findings of this study have some important implications in terms of research and policy. It is clear that discussions about preferred flavors was 1 reason that users used the UnderageJuul subreddit and also that many users used this venue to explore ways to obtain access to JUUL. At the same time, in the 6 months that this venue existed, it was not heavily used. However, because about half of the UnderageJuul users also used the JUUL subreddit, there are alternative venues whereby youth could obtain information on flavors and methods to obtain JUUL. Our analysis of the subreddit for underage JUUL users suggests that social media data are a valuable data source for rapid public health surveillance, especially for emerging products such as JUUL, as the popularity of such products is often accompanied by discussions and promotions of the products on social media [8]. There are several limitations of these data, and they should not be the only source of information, but they provide a unique and potentially real-time source of data to better understand behavioral intentions, potential demographic variables, purchase behaviors, social networks (which were not assessed in this analysis), temporal changes across a variety of variables, and other data that could be valuable to the public health, research, and regulatory communities.

In addition, our findings indicate that social media could be a valuable surveillance tool for federal and state authorities responsible for regulating stores that sell e-cigarettes. Each state in the United States has a robust, FDA-funded process for tracking and regulating such stores, and social media data could be used to identify stores where additional assessment or observation and enforcement may be needed. When used along with other sources of data, social media data can point to emerging issues that need to be addressed in more depth.