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Hepatitis B, Acute

By Anna E. Rutherford, MD, MPH, Assistant Professor of Medicine, Harvard Medical School; Clinical Director of Hepatology, Brigham and Women’s Hospital

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.

  • 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.

  • There is no specific treatment for acute hepatitis B, but most people recover completely.

  • If severe (fulminant) hepatitis develops, antiviral drugs can help, but the best hope of survival is liver transplantation.

The hepatitis B virus is the second most common cause of acute viral hepatitis. In the United States, about 3,000 cases of acute hepatitis B infection are reported annually—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 is estimated to be close to 20,000 each year.

Occasionally, hepatitis D develops 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 drugs or when needles are reused to apply tattoos.

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.

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.

Anyone with hepatitis B, including carriers, can transmit the virus. Carriers are people who have been infected but no longer have symptoms.

Whether insect bites can transmit this virus is not clear.

Many cases of hepatitis B have no known source.


In general, hepatitis B is more serious than hepatitis A and is occasionally fatal, especially in older people. 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, especially in adults.

About 5% of adults infected with the hepatitis B virus develop chronic hepatitis B or become carriers. However, up to 90% of infected newborns and up to 50% of infected young children develop chronic hepatitis B. The younger the child, the greater the chance of developing chronic hepatitis B.


  • Blood tests

Doctors suspect hepatitis based on typical symptoms, such as jaundice.

Testing for acute hepatitis B usually begins with blood tests to determine how well the liver is functioning and whether it is damaged (liver function tests). Liver function tests involve measuring the levels of liver enzymes and other substances produced by the liver. These tests may help establish or exclude the diagnosis of hepatitis, identify the cause, and determine the severity of liver damage.

Blood tests are also done to help doctors identify which hepatitis virus is causing the infection. These tests can detect the following:

  • Antibodies produced by the person's immune system in response to the specific hepatitis virus

  • Antigens of the specific hepatitis virus (antigens are any substances that can trigger an immune response in the body)

If hepatitis B virus is confirmed and is severe (fulminant), doctors also test for the hepatitis D, which is present in up to 50% of people with fulminant hepatitis B.


High-risk behavior, such as sharing needles to inject drugs and having several 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—see Figure: Vaccinating Infants and Children)

  • 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.

Worldwide vaccination of all people against hepatitis B is desirable but expensive.

Booster doses of hepatitis B vaccine are not recommended for adults and children with a normal immune system. However, the vaccine may be less effective in people with certain conditions, such as those being treated with hemodialysis or taking drugs that suppress the immune system. In people with these conditions, doctors do yearly blood tests to measure levels of antibodies to hepatitis B and thus determine whether people are still protected against hepatitis B. If tests indicate that they are not protected, they are given another (booster) dose of the vaccine.

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.

People who are not vaccinated and have been exposed to hepatitis B, including infants born to mothers with hepatitis B, are given hepatitis B immune globulin (by injection into a muscle) and the vaccine. This combination prevents chronic hepatitis B in 90 to 95%, or it makes the disease less severe. Hepatitis B immune globulin contains antibodies obtained from the blood of people who have high levels of antibodies to hepatitis.

If people come in contact with the blood of someone who has hepatitis B, they are given hepatitis B immune globulin by injection. If they have not been vaccinated against hepatitis B, they are also vaccinated. If they have been vaccinated, blood tests are done to determine whether they are still protected. If they are not, they are vaccinated.


  • General measures

  • For severe (fulminant) hepatitis, antiviral drugs and liver transplantation

There is no specific treatment for acute viral hepatitis, including 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.

If itching occurs, cholestyramine, taken by mouth, may relieve the itching.

If fulminant hepatitis develops, an antiviral drug, usually entecavir or tenofovir, is used. These drugs are taken by mouth. They increase the chance of survival.

Liver transplantation is the most effective treatment for fulminant hepatitis B and is the best hope of survival, particularly for adults.

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