General anesthetics are medications given to patients to prepare them for surgery which cause a total loss of consciousness and sensation. It is not known exactly how these drugs actually work, but there are several theories. Although these theories differ, they all indicate a disruption in the receptor cells of the central nervous system which prevent pain from being experienced.

There are two possible ways to administer a general anesthetic, intravenously or though inhalation. In most cases a combination of the two methods is used. A doctor called an anesthetist will administer the anesthetic and monitor it closely during the surgery, afterwards it will be reversed and the patient will become conscious.

Inhaled anesthetics are given to the patient through a mask which covers his or her nose and mouth. These vaporized liquids or gases are mixed with oxygen, air and occasionally nitrous oxide in an anesthesia machine from which they are pumped through into the breathing mask and inhaled. The levels of the medication and the patient's response to it are constantly monitored by this machine. Some commonly used inhaled compounds are Sevoflurane, Isoflurane, and Desflurane.

Injectable anesthetics are typically fast-working and work to both induce unconsciousness and maintain it during the procedure by means of an intravenous drip. In some cases benzodiazepines are given simultaneously as a sedative. The drugs most used for surgical IV's include Etomidate and Propofol.

The use of a general anesthetic is usually indicated when the procedure to be performed is one that is lengthy and more complicated. The patient will discuss the issue of the most suitable type of anesthesia with the anesthetist. Examples of surgeries almost always requiring a general include removal of gallbladder or appendix, hernia repair, and hysterectomy.

Before the patient is given the anesthetic, the anesthetist will normally ask him or her several questions to determine if there is an increased risk. Such risks are very rare, but anesthesia does come with its potential dangers. Patients with allergies, smoking and drinking habits, and obesity are more likely to be affected by these complications. Another reason for such incidents is patients not following instructions properly, such as eating before surgery which may result in vomiting and aspiration.

Anesthesia has four stages. The first involves the induction of unconsciousness. The second stage is known as the REM stage. The third stage is termed "surgical anesthesia" and is characterized by constriction of the pupils, relaxation of the muscles, and regular breathing, this is the most stable stage during which the surgery will be performed. Stage four is to be avoided, as it is classified as overdose of the compounds administered and may be fatal if not reversed.

During the procedure the patient's vital signs will be closely watched to ensure they are not in jeopardy. There are also some side effects which may be experienced after the use of general anesthetics. The patient may feel nauseous, have chills, be dizzy, or have a sore throat due to the insertion of a breathing tube. These feelings typically abate in a few hours and a full recovery will take place. The benefits of this type of anesthesia normally outweigh the minor discomforts which can accompany it.