Following the Food and Drug Administration (FDA) approval of lifileucel and afami-cel for patients with advanced melanoma and synovial sarcoma, respectively, there is a need for improved understanding and guidance regarding the management of toxicity associated with adoptive cellular therapies (ACTs) for solid tumours. Further approvals are expected in coming years, with toxicity management representing a significant consideration for centres looking to implement such advanced therapy medicinal products. Importantly, first-generation tumour-infiltrating lymphocyte therapies are associated with unique toxicities compared with gene-modified T-cell therapies such as chimeric antigen receptor T-cell therapy (CAR T) and T-cell receptor-modified therapy (TCR T), presenting novel challenges for treating healthcare professionals. Extrapolating from experience with CAR T in the field of haemato-oncology, coupled with the historical use of high-dose interleukin-2 in solid tumour therapeutic regimens and more recently lifileucel and afami-cel, has led to the development of core principles for managing toxicity, which is discussed here. Looking to the future, a rapidly developing field with next-generation ACT products, a basic knowledge of such core principles will be an important foundation for healthcare professionals working in this space.