Idelalisib is a first-in-class selective, oral, phosphatidylinositol 3-kinase delta (PI3Kδ) inhibitor approved for the treatment of several types of blood cancer. Idelalisib has demonstrated significant efficacy and a tolerable safety profile in clinical trials. However, the US prescribing information contains a black box warning for fatal and/or severe diarrhea or colitis, hepatotoxicity, pneumonitis and intestinal perforation. An expert panel was convened to review the pathology of these treatment-emergent adverse events (TEAEs) to propose key management tools for patients receiving idelalisib therapy. This article provides an overview of idelalisib TEAEs reported in clinical trials, and a summary of the panel's recommendations for identification and management of idelalisib treatment-emergent diarrhea or colitis as well as a discussion of transaminitis and pneumonitis. For idelalisib-related diarrhea or colitis (including unresolved grade 2 and grade ≥ 3), after exclusion of infectious causes, the panel recommends individualized treatment with budesonide or oral or intravenous steroid therapy.