Randomised clinical trials offer a unique opportunity for capturing safety information under a controlled setting that minimises biases in the comparison of different therapeutic options. Nevertheless, empirical evidence across diverse medical fields suggests that the reporting of safety information in clinical trials is largely neglected and receives less attention compared with efficacy outcomes. An analysis of 192 randomised trials has shown that reasons for withdrawals due to toxicity were specified per study arm in only 46% of the trial reports. Adequate reporting of clinical adverse effects and laboratory-determined toxicity occurred in only 39 and 29% of the trials, respectively, even with lenient definitions of what constitutes adequate reporting. The use of standardised scales for adverse effects is a prerequisite for improved reporting on safety in randomised trials. Safety data need to be collected and analysed in a systematic fashion and active surveillance for toxicity during the conduct of a randomised trial is preferable to passive surveillance. Standardised reporting of safety data does not necessarily require extensive space to accomplish. It is essential to provide numerical data per study arm on each type of adverse effect along with a categorisation of the severity of the adverse effects with an emphasis on severe and life-threatening reactions. The severity grading must be referred to well-known standardised scales and new scales need to be carefully defined. Information on withdrawals due to toxicity is also important to report, along with the specific reasons leading to discontinuation. Tabulation of information may be helpful and rare or not previously reported adverse effects should be described in detail. The availability of newer options such as electronic publication, publication of raw databases, large database research, meta-analytic approaches, and prospective registration of clinical trials and of their databases may further improve the safety insights we can gain from randomised clinical trials.