Various forms of restraint may be used in a variety of health care settings to control behaviour. Laws and policies regulate the use of physical and mechanical restraint across health care settings, but there is a gap in relation to the regulation of chemical restraint. This may partly be because of problems in defining the term and partly because of a lack of information as to the extent of the use of drugs aimed at controlling behaviour rather than ameliorating a medical condition. This column provides an overview of current definitions and argues that there is a need for national guidance as to what constitutes chemical restraint in order to reduce its use.