Electronic cigarettes (ECs) are thought to be less harmful than traditional combustible cigarettes and were originally intended to help smokers quit. Over the past two decades, they have especially gained popularity with the younger generation. To date, there are over 7000 unique e‐liquid flavours available and over 400 different e‐cigarette brands. The accuracy of nicotine strength labelling in e‐liquids was assessed in this work. Twenty‐three studies from around the world were chosen to assess the level and frequency of nicotine mislabelling in 545 e‐liquid products. Nicotine strengths were most commonly mislabelled by between 5% and 20%, with the majority testing lower than what the label indicated. Fifteen European e‐liquids that were assessed were labelled as 20 mg/ml or less, yet when tested, they contained more than 20 mg/ml of nicotine. One e‐liquid that was supposed to contain no nicotine in fact contained 23.91 mg/ml of nicotine. Furthermore, the difference between the medians of the available labelled and experimental nicotine concentrations was significant (p < 0.001, Wilcoxon signed rank test). Preliminary studies show that high nicotine levels delivered via aerosol increase the risk for nicotine poisoning and cause airway inflammation. Other EC ingredients, such as flavourings, contribute to EVALI and ‘popcorn lung’. There is evidence that certain flavourings, such as menthol, reinforce the effects of nicotine and modify drug absorption and metabolism. There is a global need for better quality control in EC products in order to make these safe for consumers.

The use of cannabidiol in electronic liquids (e-liquids) is becoming increasingly widespread, and the current regulations enforced onto nicotine-containing e-liquids are not applicable to cannabidiol-based products. This has led to concerns about the quality of cannabidiol vapes. Articles investigating the reliability of product labelling were reviewed using systematic review criteria. Of 70 e-liquids, 77.1% of the e-liquids tested in the articles were found to have underestimated or overestimated the cannabidiol quantities stated in the product labelling. Statistical analysis confirmed that there was a significant difference between the labelled and analysed cannabidiol concentrations (p < 0.05, Mann-Whitney U and Wilcoxon Signed Rank).Inaccuracies in received cannabidiol dosages could lead to an increased risk of adverse reactions or limit the therapeutic effect received, highlighting the benefit of enforcing specific regulations on cannabidiol-based e-liquids to protect consumer safety and guarantee product efficacy.