The liver is one of the largest organs in the body, occupying the upper right quadrant of the abdomen. It is vital to life, processing nutrients, manufacturing bile, and making poisonous substances such as alcohol, ammonia, nicotine and drugs harmless. Old red blood cells are removed from the blood by the liver and the spleen, and the iron in them is recycled to the bone marrow to make new ones. If the liver is damaged, these and many other processes are impaired.

Hepatitis describes inflammation of the liver cells, often caused by viruses. It can also be caused by autoimmune diseases, alcohol, drugs, chemicals and environmental toxins.

Hepatitis can be a simple self-limiting condition with complete recovery, or it can be life-threatening or result in a chronic, life-long disease.

Acute hepatitis

Acute hepatitis can begin gradually or suddenly. Its course is limited and it seldom lasts longer than two months. Rarely, acute hepatitis can cause severe liver damage.

Chronic hepatitis

The chronic forms of hepatitis persist for more than three months. They are usually categorised as either chronic persistent hepatitis, or chronic active hepatitis.

Chronic persistent hepatitis is usually mild, causing limited damage to the liver. But sometimes more extensive liver damage can occur over a longer period, leading to chronic active hepatitis.

Chronic active hepatitis results if there is extensive damage to the liver, and can lead to cirrhosis.

Causes of viral hepatitis

Most cases of hepatitis are caused by viruses which attack the liver and these are usually named with a letter from A to G. The cause is sometimes not known, and there are probably more viruses yet to be discovered.