The ionizing radiation harnessed in electron microscopes or synchrotrons enables unique insights into nanoscale dynamics. In liquid-phase transmission electron microscopy (LP-TEM), irradiating a liquid sample with electrons offers access to real space information at an unmatched combination of temporal and spatial resolution. However, employing ionizing radiation for imaging can alter the Gibbs free energy landscape during the experiment. This is mainly due to radiolysis and the corresponding shift in chemical potential
however, experiments can also be affected by irradiation-induced charging and heating. In this review, the state of the art in describing beam effects is summarized, theoretical and experimental assessment guidelines are provided, and strategies to obtain quantitative information under such conditions are discussed. While this review showcases these effects on LP-TEM, the concepts that are discussed here can also be applied to other types of ionizing radiation used to probe liquid samples, such as synchrotron X-rays.