Acute hepatitis B is inflammation of the liver that is caused by the hepatitis B virus and that lasts from a few weeks up to 6 months.
Hepatitis B is spread through contact with blood or other bodily fluids of infected people, as when people share unsterilized needles to inject illicit drugs.
Hepatitis B causes typical symptoms of viral hepatitis (including loss of appetite, a general feeling of illness, and jaundice) and may cause a severe form of hepatitis called fulminant hepatitis.
Doctors diagnose hepatitis B based on blood tests.
There is no specific treatment for acute hepatitis B.
Most people recover completely, but a few develop chronic hepatitis B.
If severe (fulminant) hepatitis develops, antiviral medications can help, but the best hope of survival is liver transplantation.
Vaccination against hepatitis B is recommended for all children and for adults likely to be exposed to the infection or to develop severe complications of the infection.
(See also Overview of Hepatitis, Overview of Acute Viral Hepatitis, and Hepatitis B, Chronic.)
The hepatitis B virus is the second most common cause of acute viral hepatitis. In the United States, over 2,000 cases of acute hepatitis B infection were reported in 2021—a decrease from the 25,000 annual cases reported before use of hepatitis B vaccine became widespread. However, many cases are not recognized or not reported. So the actual number of new infections may be much higher. It was estimated to be about 21,600 in 2018.
Occasionally, hepatitis D infection coexists in people with acute hepatitis B.
Transmission of hepatitis B
Hepatitis B is less easily transmitted than hepatitis A. Transmission commonly occurs when needles are reused without being first sterilized—as when people share needles to inject illicit drugs or when tattoo needles are reused.
Transmission through blood transfusions is possible but is now rare in the United States because blood is screened.
Hepatitis B is also spread through contact with saliva, tears, breast milk, urine, vaginal fluid, and semen, but such spread is less common than blood-to-blood transmission.
Transmission may occur between sex partners, both heterosexual and homosexual. Also at increased risk are people living in close quarters (such as prisons and mental health institutions) because contact with another person's body fluid is more likely.
A pregnant woman infected with hepatitis B can transmit the virus to her baby during birth (see Hepatitis B Virus [HBV] Infection in Newborns).
Anyone with hepatitis B, even people who do not have symptoms, can transmit the virus.
Whether insect bites can transmit this virus is not clear.
Many cases of hepatitis B have no known source.
Chronic hepatitis B
Overall, about 5 to 10% of people infected with the hepatitis B virus develop chronic hepatitis B.
The younger the person is when acute hepatitis B occurs, the higher the risk of developing chronic hepatitis B:
Infants: 90%
Children aged 1 to 5 years: 25 to 50%
Adults: About 5%
If hepatitis B becomes chronic, severe scarring of the liver (cirrhosis) can develop, and liver cancer can eventually develop.
Symptoms of Acute Hepatitis B
In general, hepatitis B is more serious than hepatitis A and is occasionally fatal, especially in older adults. The infection can be mild or very severe (called fulminant hepatitis). When people with hepatitis B also have hepatitis D, symptoms are more severe.
Most people with hepatitis B have typical symptoms of viral hepatitis. These symptoms include
Loss of appetite
A general feeling of illness (malaise)
Fever
Nausea and vomiting
Jaundice (yellowing of the skin and whites of the eyes)
Joint pains and itchy red hives on the skin (wheals) are more likely in people with hepatitis B than with other hepatitis viruses.
Symptoms last from a few weeks up to 6 months.
If fulminant hepatitis develops, people can become very ill very quickly. Toxic substances normally removed by the liver build up in the blood and reach the brain, causing hepatic encephalopathy. People may lapse into a coma within days to weeks. Fulminant hepatitis may be fatal without a liver transplant, especially in adults.
Diagnosis of Acute Hepatitis B
Blood tests
Doctors suspect hepatitis based on typical symptoms, such as jaundice.
Testing usually begins with blood tests to determine how well the liver is functioning and whether it is damaged (liver tests). Liver tests involve measuring the levels of liver enzymes and other substances produced by the liver.
If tests detect liver abnormalities, other blood tests are done to check for hepatitis virus infection. These blood tests can identify parts of specific viruses (antigens), specific antibodies produced by the body to fight the virus, and sometimes genetic material (RNA or DNA) of viruses.
If hepatitis B virus is confirmed and is severe (fulminant), doctors also check for the hepatitis D virus, which is present in up to 50% of people with fulminant hepatitis B.
Treatment of Acute Hepatitis B
General measures
For severe (fulminant) hepatitis, antiviral medications and liver transplantation
There is no specific treatment for acute hepatitis B.
People with hepatitis B should not drink alcohol because it can damage the liver further. There is no need to avoid certain foods or limit activity.
Most people can safely return to work after jaundice resolves.
Liver transplantation is the most effective treatment for fulminant hepatitis B and is the best hope of survival, particularly for adults.
Prevention of Acute Hepatitis B
High-risk behavior, such as sharing needles to inject drugs and having multiple sex partners, should be avoided.
All blood donors are tested for hepatitis B to prevent the spread of hepatitis B virus through transfusions. Also, even though the chance of getting hepatitis from transfusions is remote, doctors use transfusions only when there is no alternative. These measures have dramatically decreased the risk of getting hepatitis from a blood transfusion.
In the United States, vaccination against hepatitis B is recommended for
All people aged 18 and younger (starting at birth)
Any adult who wishes protection from hepatitis B
All unvaccinated adults whose risk of getting hepatitis B is increased, including pregnant women
People with chronic liver disease
If family members and close contacts of people with chronic hepatitis B have not been vaccinated, they should be vaccinated with the hepatitis B vaccine.
If the level of hepatitis B virus (viral load) is high in pregnant women, they are often given antiviral medications during the last trimester of pregnancy to prevent transmission of the virus from mother to child.
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
Centers for Disease Control and Prevention: Hepatitis B: This website provides links to an overview of hepatitis B (including definitions, statistics, transmission, and screening) and information about the hepatitis B vaccine, symptoms, diagnosis, and treatment, as well as links to information for health care practitioners. Accessed May 10, 2024.
