Hepatitis B | Symptoms & Causes

What causes hepatitis B?

Hepatitis B is caused by the hepatitis B virus (HBV). The virus is passed from person to person through contact with blood infected with HBV, sexual intercourse, or intravenous drug use. Mothers infected with HBV can pass the virus on to their children during childbirth, though doctors can reduce that risk by giving newborns both the hepatitis B vaccine and a medication called hepatitis B immune globulin (or HBIG) within about 12 hours of birth.

While the number of new cases of hepatitis B in the United States has dropped dramatically in the last two decades — thanks to the vaccination — the Centers for Disease Control and Prevention estimates between 885,000 and 2.2 million people in the U.S. have chronic HBV infection.

What is the liver, and what does it do?

The liver is the second largest organ in the body, located in the abdominal cavity. The liver helps the body in many ways:

  • the liver produces proteins that allow blood to clot normally, transport oxygen, and support the immune system
  • it produces bile, a substance that helps digest food
  • it stores extra nutrients
  • it helps clean the bloodstream of harmful substances
  • it helps control blood sugar and cholesterol levels

How does hepatitis B affect the liver?

When infected, the liver becomes inflamed, which may cause the healthy, soft tissues in the liver to harden and scar. If not stopped, inflammation and scarring can lead to serious liver diseases such as cirrhosis or liver cancer. If the damage is severe enough, the liver may not perform all of its functions normally.

What are the symptoms of hepatitis B?

The majority of children with acute hepatitis B have no symptoms. Parents typically have no idea their child is infected. Over time, as the virus causes increasing damage to the liver, the following symptoms may appear:

  • fatigue
  • nausea
  • dark urine
  • muscle soreness
  • vomiting
  • loss of appetite
  • stomach pain
  • jaundice