Gangrene occurs when tissues in the body die because of a lack of proper blood flow, according to PubMed Health. Although gangrene most commonly affects the fingers, toes and other external parts of the body, it can also affect internal organs, notes WebMD.
Skin discoloration is the most common sign of gangrene. Bronze or red skin is commonly associated with internal gangrene, whereas black or blue skin is commonly associated with external gangrene. Severe pain followed by a numb feeling might occur. The affected area might have a discharge that smells foul. Internal gangrene might cause a person to be confused, run a fever or have a low blood pressure.