The SIDER (Side Effect Resource) database, developed by Michael Kuhn, Ivica Letunic, Lars Juhl Jensen, and Peer Bork, is a comprehensive resource for adverse drug reactions (ADRs). The current release, SIDER 4, includes data on 1430 drugs, 5880 ADRs, and 140,064 drug–ADR pairs, representing a 40% increase from the previous version. SIDER provides detailed information on the frequency of side effects from package inserts, available for 39% of drug–ADR pairs, with 19% of these pairs comparable to placebo treatment. The database also includes a dataset of drug indications extracted using Natural Language Processing (NLP), which helps reduce false positives by identifying medical terms that do not correspond to ADRs. SIDER is widely used in academic research, with an average monthly download of 74 times in the past year. The database is available at <http://sideeffects.embl.de/> and can be interactively browsed and searched on its website.The SIDER (Side Effect Resource) database, developed by Michael Kuhn, Ivica Letunic, Lars Juhl Jensen, and Peer Bork, is a comprehensive resource for adverse drug reactions (ADRs). The current release, SIDER 4, includes data on 1430 drugs, 5880 ADRs, and 140,064 drug–ADR pairs, representing a 40% increase from the previous version. SIDER provides detailed information on the frequency of side effects from package inserts, available for 39% of drug–ADR pairs, with 19% of these pairs comparable to placebo treatment. The database also includes a dataset of drug indications extracted using Natural Language Processing (NLP), which helps reduce false positives by identifying medical terms that do not correspond to ADRs. SIDER is widely used in academic research, with an average monthly download of 74 times in the past year. The database is available at <http://sideeffects.embl.de/> and can be interactively browsed and searched on its website.