In the practice of medicine anesthesia or anaesthesia is a state of temporary induced loss of sensation or awareness. It may include analgesia (relief from or prevention of pain), paralysis (muscle relaxation), amnesia (loss of memory), or unconsciousness. A patient under the effects of anesthetic drugs is referred to as being anesthetized. Anesthesia enables the painless performance of medical procedures that would cause severe or intolerable pain to an unanesthetized patient.