The liver is a unique organ. It is the only organ in the body that is able to regenerate. With most organs, such as the heart, the damaged tissue is replaced with scar, like on the skin. The liver, however, is able to replace damaged tissue with new cells. If up to 50 to 60 percent of the liver cells may be killed within three to four days in an extreme case like a Tylenol overdose, the liver will repair completely after 30 days if no complications arise.

Complications of liver disease occur when regeneration is either incomplete or prevented by progressive development of scar tissue within the liver. This occurs when the damaging agent such as a virus, a drug, alcohol, etc., continues to attack the liver and prevents complete regeneration. Once scar tissue has developed it is very difficult to reverse that process. Severe scarring of the liver is the condition known as cirrhosis. The development of cirrhosis indicates late stage liver disease and is usually followed by the onset of complications.