The hepatitis B virus usually only stays in the system for around one to three months and is therefore an acute infection. The infection usually resolves without treatment and most adults recover completely.
However, in around 1 in 20 affected adults, the infection is chronic and stays in the body for six months or more. This chronic form of hepatitis B is very common in young infants and children. About 90% of infants who are infected as newborns and 20% of young children affected go on to develop chronic infection. Even if these children do not have symptoms, they can still pass the infection onto other people.
About 20% of people who develop long-term infection will develop liver disease and suffer from scarring or cirrhosis of the liver. Around 10% of those who develop cirrhosis will go on to develop liver cancer.
Cirrhosis of the liver
Cirrhosis of the liver can take up to 20 years to develop and may not cause any symptoms initially. Eventually, the liver damage can lead to symptoms such as weakness, loss of appetite, nausea, vomiting, itchy skin, jaundice, pain in the right upper abdomen, and fluid build up in the abdomen (ascites).
Around 10% of individuals with liver cirrhosis go on to develop liver cancer. The symptoms of liver cancer include weight loss, loss of appetite, nausea and vomiting, and jaundice.
Fulminant hepatitis B
This is a rare complication of acute hepatitis B where the immune system attacks the liver and causes severe damage. The condition affects around 1 in 100 adults who have chronic hepatitis B, but children are affected much more rarely. Some of the symptoms of fulminant hepatitis B include confusion, jaundice and ascites.
Reviewed by Sally Robertson, BSc