Drug-induced liver injury (DILI) is an adverse reaction to drugs or other xenobiotics that occurs either as a predictable event when the subject is exposed to toxic doses of some compounds (acetaminophen overdose) or in an unpredictable way with many drugs in common use. Drugs can be harmful to the liver in a susceptible subject on the background of genetic and environmental factors. This accounts for modifications in the hepatic metabolism and excretion of the agent leading to cellular stress, direct cell death, activation of an adaptive immune response and a failure to adapt with progression to overt liver injury. Idiosyncratic DILI is a relative rare liver disorder but can be severe and even fatal, presenting with a variety of phenotypes, which mimic almost every other liver disease. Diagnosis of DILI relies on the exclusion of other etiologies of liver disease as specific biomarkers are still lacking. Clinical scales such as CIOMS/RUCAM can support the diagnostic process but need a refinement. A number of clinical variables, validated in prospective cohorts, can be used to predict a more severe DILI outcome. Although no pharmacological therapy has yet been adequately tested in randomized clinical trials, corticosteroids can be useful, particularly in the emergent form of DILI related to immune checkpoint inhibitors.

Idiosyncratic drug-induced liver injury (DILI) is a common cause for drug withdrawal from the market and although infrequent, DILI can result in serious clinical outcomes including acute liver failure and the need for liver transplantation. Eliminating the iatrogenic "harm" caused by a therapeutic intent is a priority in patient care. However, identifying culprit drugs and individuals at risk for DILI remains challenging. Apart from genetic factors predisposing individuals at risk, the role of the drugs' physicochemical and toxicological properties and their interactions with host and environmental factors need to be considered. The influence of these factors on mechanisms involved in DILI is multi-layered. In this review, we summarize current knowledge on 1) drug properties associated with hepatotoxicity, 2) host factors considered to modify an individuals' risk for DILI and clinical phenotypes, and 3) drug-host interactions. We aim at clarifying knowledge gaps needed to be filled in as to improve risk stratification in patient care. We therefore broadly discuss relevant areas of future research. Emerging insight will stimulate new investigational approaches to facilitate the discovery of clinical DILI risk modifiers in the context of disease complexity and associated interactions with drug properties, and hence will be able to move towards safety personalized medicine.