A medication error is any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the health care professional or patient. A prescribing error is a medication error related to an error in prescribing. Many ADRs are considered in retrospect to have been ‘avoidable’ with more care or forethought. In other words, an adverse event considered by one prescriber to be an unfortunate ADR might be considered by another to be a prescribing error. An administration error is related to a failure in the task of giving the medicine to the patient, even though the prescription that directs the administration is correct and the correct medicine has been supplied (e.g. the medicine is given by the wrong route). A dispensing error occurs when the prescription is correct but the wrong medicine is supplied, normally be a pharmacist.