Hepatitis B overview

Last updated May 16, 2024, by Marisa Wexler, MS
Fact-checked by Marta Figueiredo, PhD

Hepatitis B is a viral infection spread by contact with bodily fluids that causes inflammation in the liver. In some cases, this form of hepatitis can result in a chronic infection that may set the stage for serious complications, such as liver failure or liver cancer.

Although hepatitis B cannot be cured, the infection can be prevented with a vaccine. Treatments are available to help mitigate serious complications of hepatitis B for those who become infected. Therefore, raising awareness about hepatitis B causes, risk factors, and symptoms is crucial to enable people to take proactive steps in disease prevention and timely treatment.

What is hepatitis B?

Hepatitis B is the most common serious liver infection in the world. Indeed, it’s estimated that about 1 in 3 people worldwide — about 2 billion people globally — have been infected with the hepatitis B virus (HBV). Because most people infected with HBV do not experience any noticeable symptoms, the virus can spread silently via contact with bodily fluids from infected people.

When the hepatitis B virus enters the body, it first causes an acute infection that usually lasts a few months and rarely causes serious health problems. In some people, however, the virus can stick around for longer and cause a long-lasting, chronic infection.

Globally, about 300 million people have a chronic hepatitis B infection, which can result in severe complications such as extensive liver scarring and cancer. In fact, chronic hepatitis B is the most common cause of liver cancer, which is the second-leading cause of premature death from cancer around the world.

The likelihood of developing chronic hepatitis B largely depends on a person’s age, being higher when the infection occurs earlier in life. Hepatitis B infection leads to chronic disease in as many as 90% of babies infected in infancy and about 30% of children younger than 6, but only in 5% of infected adults.

Causes

Hepatitis B is caused by an infection with the hepatitis B virus. While viruses associated with other forms of viral hepatitis, such as hepatitis A and hepatitis C, also mainly result in damage to the liver, the hepatitis B virus has some important differences from the others.

For one, HBV is primarily spread by contact with bodily fluids, such as blood, semen, or vaginal secretions. The hepatitis A virus, meanwhile, is transmitted through the fecal-oral route, and the hepatitis C virus through exposure to infected blood. HBV also can survive outside the body for seven days or longer and is resistant to many common disinfectants, while other common viruses are more susceptible to such substances and thus usually do not survive as long.

Hepatitis B transmission can commonly occur during childbirth, by passing from the infected mother to the newborn baby, as well as during the preschool ages, when children may be exposed to each other’s blood, usually through scrapes, sores, or cuts. It also is frequently spread through contact with blood or other body fluids during unprotected sex with an infected partner, and by sharing contaminated needles to inject drugs.

In the U.S., the two most common risk factors for having an acute HBV infection are injection drug use and having multiple sexual partners. Transmission in healthcare settings, however, whether via blood transfusions, accidental needle sticks, or surgical procedures, is rare.

Because of how hepatitis B is transmitted, the virus cannot be spread through casual contact with an infected person, such as by shaking hands, or via consumption of contaminated food or water. However, transmission can occur through sharing of items that can break the skin or via contact between open sores, meaning that people who live with someone who is infected have an increased risk of infection.

Other risk factors for an HBV infection include:

being born in regions where hepatitis B is especially common, including Africa and the Western Pacific
being incarcerated in a jail, prison, or other detention setting where there is a higher exposure to people engaging in high-risk behaviors
undergoing maintenance dialysis, a medical procedure that aims to replace the functions of the kidneys by removing waste products and excess fluid from the blood
having a job, including in healthcare, where there’s a risk of exposure to contaminated blood, bodily fluids, or open sores.

Symptoms

Upon HBV infection, there is an incubation period that ranges from 30 to 180 days, or from about one month to nearly six months. During this time, someone infected with HBV may be contagious and able to spread the virus to other people, even in the absence of obvious signs of hepatitis B.

Following that incubation period, infected people can experience acute hepatitis B symptoms for up to six months, after which the infection will either resolve or linger in the body. In the latter case, there is the development of a chronic infection that may result in chronic hepatitis B symptoms.

Acute hepatitis B symptoms

About 70% of people infected with HBV do not develop any symptoms during the acute phase of the infection. The rate of asymptomatic patients is particularly higher in children younger than 5, who almost never have symptoms from acute hepatitis B. Older children and adults are more likely to experience symptoms.

If symptoms do occur, they typically appear anywhere from 2-5 months after the infection itself. The average time from infection to symptom onset is about three months. Acute hepatitis B symptoms can include:

fever
fatigue
loss of appetite
nausea and vomiting
abdominal pain
dark urine
pale stools
joint pain
jaundice (yellow color in the skin or the eyes)
skin rash.

The severity of symptoms in acute hepatitis B can range from mild to severe. As many as 1% of adults with HBV will experience fulminant hepatitis, a severe condition that requires urgent medical attention due to the potential for life-threatening liver failure, which occurs when the liver is not able to function adequately.

Symptoms of acute hepatitis B usually resolve within a few weeks after appearing, though they can last for as long as about six months.

Chronic hepatitis B symptoms

Anyone whose immune system is not able to get rid of the hepatitis B virus after more than six months is said to have chronic hepatitis B. Most of these patients don’t have any notable symptoms from the infection itself, and some may be symptom-free for years or even decades. While estimates point to several hundred million people chronically living with hepatitis B globally, about two-thirds don’t know they are infected and are not receiving appropriate care.

People with chronic hepatitis B also may experience symptoms similar to those of acute infection, including fatigue and loss of appetite. When someone with chronic disease starts to experience symptoms, however, it’s usually because the disease has progressed to the point that the liver is starting to have problems functioning.

The first findings suggesting severe liver problems in these patients often include an enlarged spleen, spider-like blood lesions on the skin, red palms, and excess fluid in the abdomen.

Diagnosis

Because signs of hepatitis B are generally nonspecific and similar to those seen in many other liver diseases, a physical examination is not enough to diagnose hepatitis B. If a person experiences symptoms suggestive of hepatitis B or has been potentially exposed to HBV, the only way to establish a hepatitis B diagnosis is via a blood test.

The U.S. Centers for Disease Control and Prevention (CDC) specifically recommends a triple panel blood hepatitis B test that checks for three blood markers. These include a protein from the HBV itself called hepatitis B surface antigen, or HBsAg, and two types of antibodies that specifically target the virus — hepatitis B surface antibodies, or anti-HBs, and antibodies against hepatitis B core antigen, known as anti-HBc.

The combination of results from a test of these three markers can help doctors determine a patient’s status with respect to hepatitis B:

Being positive for both HBsAg and anti-HBc, but negative for anti-HBs, indicates an ongoing acute hepatitis B infection. A fourth marker called IgM anti-HBc can differentiate between ongoing acute and chronic infections, as it is only found during acute infections. However, IgM anti-HBc levels are only measured if clinicians aren’t sure whether the patient is experiencing acute or chronic hepatitis B.
Being negative for HBsAg and positive for both anti-HBc and anti-HBs indicates that the person has previously experienced a hepatitis B infection, but that the infection is now resolved.
Being positive only for anti-HBs usually means immunity to HBV was achieved with prior vaccination against the virus.
Being positive only for anti-HBc means that a few different scenarios are possible. This can be a false-positive, a sign of possible undetected infection, or a case of reduced hepatitis B immunity after the resolution of a previous infection. Patients with this result should consult their healthcare team about how to interpret the findings.

People with suspected or confirmed hepatitis B also may undergo additional testing to assess liver function and measure a person’s viral load, meaning the amount of DNA from the virus in the blood.

HBV’s genetic material is detectable about a month after infection — about 21 days before HBsAg — and generally reaches its highest levels at the time of acute hepatitis B, gradually dropping from that point on and becoming undetectable when the infection is resolved.

Combined with results from these tests, an assessment of an individual’s viral load can be helpful. It can diagnose some cases of early acute hepatitis B (when HBsAgs are not yet detected), distinguish active from inactive chronic HBV infection, and monitor a patient’s response to anti-HBV treatment.

Patients with active chronic HBV infection — those with a high viral load and who are HBsAg-positive — are at greater risk for more serious liver disease and also are more contagious than those with inactive chronic HBV infection (low or undetectable HBV DNA levels, and HBsAg-negative).

As hepatitis B often doesn’t cause obvious symptoms, the CDC recommends that all adults be tested for the virus at least once in their lifetime. Those at a higher risk of HBV infection should be tested regularly, per the CDC. Pregnant people should be screened for hepatitis B at the start of every pregnancy due to the risk of HBV transmission to their offspring.

To avoid stigma, the agency also notes that hepatitis B tests should be offered without question to anyone who requests one.

Treatment

The goal of hepatitis B treatment is to prevent viral replication, limit liver inflammation, and ultimately reduce the risk of more serious complications. Although there is no hepatitis B cure, appropriate treatment can allow patients to live longer and maintain a better quality of life.

Treating acute hepatitis B

No treatments are specifically approved for acute hepatitis B — the vast majority of patients will clear the acute infection without disease-specific medications. Supportive care may be given to help patients stay comfortable and healthy while their body fights the infection.

Hepatitis B self-care tips include:

getting bed rest
eating a healthy, well-balanced diet
drinking lots of fluids
avoiding substances that can stress the liver, such as alcohol and aspirin
using symptom-relieving treatments, including pain medications, as directed by a physician
maintaining an open line of communication with healthcare providers.

In the rare cases where acute hepatitis B does cause serious problems, antiviral medications approved for chronic hepatitis B may be given to help control the infection.

Treating chronic hepatitis B

While some people with chronic hepatitis B may not need medications to fight the infection, those who exhibit signs of active infection (high viral load) and/or evidence of liver damage should be given specific hepatitis B treatment. There are several first-line treatments available for people with chronic hepatitis B:

Oral antiviral medications work by stopping HBV from replicating in the body. Several antivirals are approved in the U.S. for treating hepatitis B, including entecavir (sold as Baraclude, with generics available); tenofovir alafenamide (sold as Vemlidy and generics); tenofovir disoproxil fumarate (sold as Viread, among others); and adefovir dipivoxil (marketed as Hepsera and others).
Interferons can be used to boost the immune system’s ability to fight off the virus. The main interferon therapies used for hepatitis B are peginterferon alfa-2a, sold under the brand name Pegasys, and interferon alfa-2b, marketed as Intron A.

According to the 2024 hepatitis B guidelines from the World Health Organization (WHO), more than half of all people with chronic hepatitis B will need treatment, and most of those starting hepatitis B treatment must continue it for life.

In cases where hepatitis B leads to liver failure, a liver transplant may be needed.

Complications

A person with chronic hepatitis B has a greater risk of developing certain complications of the disease. Among these are:

cirrhosis, or permanent scarring of the liver, which can lead to liver failure
portal hypertension, or increased pressure in the liver’s main blood vessel due to cirrhosis
hepatocellular carcinoma, the most common type of liver cancer
other infections, including with the hepatitis D virus, which only infects people with hepatitis B.

One other potential complication is hepatitis B reactivation, in which HBV disease activity suddenly returns in someone with a previously inactive or resolved infection. This usually happens in people with chronic hepatitis B whose immune systems are weakened, and can be severe

An early hepatitis B diagnosis, followed by regular monitoring and appropriate disease management, can help to reduce the risk of serious complications.

Hepatitis B vaccine

Vaccination is the most effective method for hepatitis B prevention. Getting a hepatitis B vaccine is universally recommended by organizations such as the CDC and WHO for all children, and for adults younger than 60.

A few different vaccines for hepatitis B are available, and all are considered very safe and highly effective. The only medical reason not to receive a hepatitis B vaccine, according to the CDC, is if a patient has experienced a serious allergic reaction to the vaccine’s components. The most common hepatitis B vaccine side effects are soreness at the injection site.

At this time, hepatitis B vaccination is recommended for all medically stable babies within the first few hours after birth. This is especially important for babies born to mothers with a known HBV infection.

Additional preventive therapies also may be given to reduce the risk of infection in these babies. These include hepatitis B immune globulin, a purified solution collected from human blood samples that contains high levels of antibodies against HBV.

If newborns aren’t healthy enough to receive the first vaccine dose in the hours after birth, the vaccine should be given as soon as it’s safe to do so.

In the U.S., available vaccines for infants include ones that protect only against hepatitis B and ones that also protect against other viruses:

Engerix-B and Recombivax-HB are among those only protecting against hepatitis B. Following the first dose, two additional doses are given one month and six months later.
Vaxelis and Pediarix both are combination vaccines that protect against hepatitis B and several other viruses. These involve three doses, given at 2, 4, and 6 months of age.

According to the CDC, older children and adults younger than 60 should also be vaccinated against hepatitis B if they have not been vaccinated already. Among adults 60 and older, who have a lower incidence of hepatitis B, vaccination is only recommended for those at high risk of hepatitis B, although older adults without HBV risk factors also may receive it.

Engerix-B and Recombivax-HB, both given as 2-4 injections over the course of six months, are approved for children and adults of all ages.

A number of other hepatitis B vaccines are solely approved for adults:

PreHevbrio is given as three injections, with the last two administered at one and six months after the first dose.
Heplisav-B is administered as two injections one month apart.
Twinrix, which protects against both hepatitis B and A, is given as 3-4 injections over the course of six months to one year.

It’s generally suggested that patients receive all doses with the same type of vaccine, but the CDC says it is acceptable to mix and match if circumstances require doing so. If a planned dose is delayed, it should be given as soon as possible, but the vaccination schedule does not have to be restarted.

While pregnancy is not a contraindication for receiving a hepatitis B vaccination, only a few vaccines have sufficient data indicating their apparent safety during pregnancy or breastfeeding. The CDC specifically recommends the vaccines Engerix-B, Recombivax HB, or Twinrix for use in pregnant patients.

In addition to vaccination, preventing hepatitis B transmission can involve using sterile equipment and maintaining safe sex practices.

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