Anesthesia refers to the drugs and gases used during an operation to relieve pain. These drugs work by blocking messages to the brain so that all or part of the body becomes insensitive to pain and feeling for as long or as short a time as needed. The three types are local anesthesia, regional anesthesia, and general anesthesia. Their effects range from a short-lived numbness, to temporary paralysis or unconsciousness, depending on the blend of products used and how they are administered. Local anesthesia is injected directly into a tissue to numb it. It is used for minor surgeries and may be coupled with a mild sedative. There are few, if any, side effects. Regional anesthesia blocks sensation in a region of the body, such as from the waist down. The two main types are spinal and epidural. Both are injected near the spinal cord. An epidural is administered through a thin plastic tube or catheter and can be given continuously during surgery. After surgery the catheter can be left in to provide post-operative pain relief. Spinal anesthesia acts faster, and produces more numbness than an epidural, but cannot be given continuously. Spinal anesthesia is often associated with headaches as it wears off. General anesthesia includes a group of agents that block pain, relax the muscles, and produce unconsciousness. It can also shut down memory function. Typically, general anesthesia agents are given by mouth or intravenously, then followed with gas. Temporary side effects of general anesthesia may include nausea, vomiting, muscle pain, or sore throat.

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