 Burns can be classified by depth , mechanism of injury , extent , and associated injuries . The most commonly used classification is based on the depth of injury . The depth of a burn is usually determined via examination , although a biopsy may also be used . It may be difficult to accurately determine the depth of a burn on a single examination and repeated examinations over a few days may be necessary . In those who have a headache or are dizzy and have a fire @-@ related burn , carbon monoxide poisoning should be considered . Cyanide poisoning should also be considered . 
