The use of unlicensed and off-label medicines in children is common because trials in children have not usually been performed during the drug development process. Consequently, the information available to paediatricians may not always be as detailed or as robust as that available when prescribing a medicine that is licensed for an approved indication. This has led to concerns that children may be receiving drugs at dosages that either lack efficacy or present safety problems. The latter in particular has received a great deal of attention. In this narrative review, we have evaluated the use of off-label and unlicensed medicines in children and whether and how frequently this predisposes to adverse drug reactions.