Agent that produces a local or general loss of sensation, including pain, and therefore is useful in surgery and dentistry .
General anesthesia induces loss of consciousness, most often using halogen ) hydrocarbons (e.g., chloroform , ethyl chloride, trichloroethylene); ethers (e.g., ethyl ether or vinyl ether); or other compounds, such as tribromoethanol, nitrous oxide , or barbiturates . Local anesthesia induces loss of sensation in one area of the body by blocking nerve conduction (see nervous system , neuron ), usually with alkaloids such as {{link=cocaine">cocaine or synthetic substitutes (e.g., lidocaine). See also anesthesiology .