In last years, the therapeutic arsenal against breast cancer increased considerably with the arrival of signaling pathway inhibitors, immunotherapy, PARP inhibitors, tyrosine kinase inhibitors and antibody-drug conjugates. Consequently, the range of potential adverse events has also widened and differs from the usual chemotherapies and endocrine therapies. Depending on the administered therapy, the same symptoms can be harmless and treated symptomatically or the warning sign of a potential serious complication requiring a rapid action. We therefore discuss in this article the therapeutic role and some typical adverse events of these new therapies.