Acute confusional state (ACS) refers to sudden impairment of cognitive function and represents a major medical emergency. The impairment may be global or confined specifically to a particular faculty of higher mental function, such as memory. This review highlights the importance of relevant medical history and clinical signs and symptoms in reaching the correct diagnosis. In this review, we have presented a diagnostic approach to a child presenting with ACS and described commonly encountered causes, their treatments and outcomes. We have also presented an algorithm for the diagnostic approach to the child with ACS.