Anesthesia is a unique medical intervention which does not itself offer any particular medical benefit and instead enables the performance of other medical interventions. The best anesthetic is therefore one with the lowest risk to the patient that still achieves the end points required to complete the other intervention. There are many different needs and goals of anesthesia. The goals (end points) are traditionally described as unconsciousness and amnesia, analgesia, and muscle relaxation. To reach multiple end points one or more drugs are commonly used (such as general anesthetics, hypnotics, sedatives, paralytics, narcotics, and analgesics), each of which serves a specific purpose in creating a safe anesthetic.

There are both major and minor risks of anesthesia. Examples of major risks include death, heart attack and pulmonary embolism whereas minor risks can include postoperative nausea and vomiting and readmission to hospital. The likelihood of a complication occurring is proportional to the relative risk of a variety of factors related to the patient’s health, the complexity of the surgery