Hepatitis B is contagious even when symptoms do not appear. According to the U.S. Centers for Disease Control and Prevention (CDC), about 30% of patients with chronic hepatitis show no signs or symptoms.
Hepatitis B symptoms are less common in infants and children than adults. Symptomatic patients usually experience the first symptoms four to six weeks after infection, and they can range from mild to severe. Common symptoms include loss of appetite, nausea and vomiting, weakness and fatigue, abdominal pain (especially near the liver), dark urine, jaundice (yellowing of the skin and eyes) and joint pain.
Anyone who has chronic hepatitis B is also susceptible to infection with another strain of viral hepatitis known as hepatitis D (formerly called delta virus). Hepatitis D virus can only infect cells if the hepatitis B virus (HBV) is present. Injection drug users who have hepatitis B are at the greatest risk.
Individuals with chronic HBV infection may develop serious liver diseases, such as cirrhosis (scarred, fibrous liver that is full of fat and not functioning properly) and liver cancer. Individuals who had HBV as an infant are at a greater risk of developing serious liver complications as an adult. Also, individuals who are infected with both hepatitis B and hepatitis D have an increased risk of developing cirrhosis or liver cancer, both of which can be fatal.
Individuals diagnosed with HBV are at risk of acute liver failure, which occurs when all the vital functions of the liver shut down. Liver failure occurs if cirrhosis is present in more than two-thirds of the liver. Liver failure requires a liver transplant and can be fatal.