Several regulatory initiatives around the world restrict the content of nicotine in electronic cigarette (e-cigarette) liquids (e-liquids) in order to minimize the risks associated with nicotine. However, to which extent levels of nicotine in e-liquids influence e-cigarettes users’ behaviour is complex and poorly defined. Extensive studies are conducted to assess the factors contributing to nicotine absorption in adults using e-cigarettes in a variety of laboratory conditions coupled with different e-cigarette devices. Nonetheless, it remains difficult to draw conclusions regarding nicotine absorption from e-cigarettes. The purpose of this study is to present a pooled analysis of publicly available studies that provide nicotine pharmacokinetic data for e-cigarettes, mainly C_max, to identify which factors influence nicotine blood absorption. The data gathered indicate that nicotine absorption is determined by a combination of many factors, including user experience, device type and e-liquid nicotine concentration. For e-cigarettes to be viable alternatives to smoking, they should provide to adult smokers who express their interest in switching to e-cigarettes an equally satisfying experience, including in terms of nicotine absorption into the body. Therefore, any regulation of e-cigarettes should take all these factors into account.