Introduction In recent years, the nicotine in e-cigarettes has been available in either a ‘free-base’ (unprotonated) or ‘nicotine salt’ (protonated) form. Additionally, e-cigarette nicotine can be either ‘synthetic’ or ‘tobacco-derived’. These dimensions of nicotine have implications for nicotine absorption, bioavailability and sensory experiences. However, it is unclear if the young people using e-cigarettes are aware of these nicotine dimensions.

Methods Data came from a cohort of Ohio youth (aged 15–24) who reported using an e-cigarette in the past 4 months (N=271). Participants were enrolled and provided background information in 2021; their 12-month follow-up survey asked about the presence, form and type of nicotine in their usual e-cigarette. Individuals who reported that they could distinguish between tobacco-derived and synthetic nicotine were additionally asked to describe the difference.

Results Of the 247 youth who reported that there was nicotine in their usual e-cigarette, 71.7% did not know whether it was free-base or nicotine salt and 75.7% did not know whether it was synthetic or tobacco-derived. Awareness was higher among youth who were using e-cigarettes at a greater frequency and quantity. The majority reported that they could not detect a difference between the experience of using synthetic vs tobacco-derived nicotine.

Conclusions These findings indicate the generally limited awareness about nicotine among youth who used e-cigarettes. Improvements in health communications and requirements for e-cigarette industry disclosures are necessary to ensure that consumers are better informed about the dimensions—and the risks—of the nicotine they are consuming.