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Disease

Hepatitis B

Learn about hepatitis B, including its symptoms, diagnosis, laboratory tests, treatment and prevention.

Last Reviewed 26 Jul 2026
Reading Time 9 min read

Overview

A routine blood test, a screening before donating blood, or a check during pregnancy is how many people first learn they have hepatitis B. Often there were no symptoms leading up to it at all, which is part of what makes this virus so easy to carry for years without knowing.

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Key Fact

How old you are when you first get infected with hepatitis B changes almost everything about what happens next. Around 90 percent of infants infected at birth go on to carry the virus for life, while about 95 percent of adults who become infected clear it completely within months, without ever needing treatment.

Warning

Yellowing of the skin or eyes, severe abdominal pain, or confusion are signs of serious liver involvement and need urgent medical care. If you have never been tested for hepatitis B, ask your doctor about screening, since most people with the infection have no symptoms at all.

AT A GLANCE

Disease Summary

Category Infectious Disease
Cause Hepatitis B virus (HBV), which infects and inflames the liver
Transmission Contact with infected blood or body fluids, including from mother to child during birth, sexual contact, and unsafe injections or exposure to sharp instruments
Body System Liver
Preventable Yes
Curable No

Symptoms

Common Symptoms

Many people with hepatitis B, especially children, have no symptoms at all. When symptoms do appear, they typically include the following.

Fatigue

A persistent, unusual tiredness is one of the most common symptoms when they occur.

Loss of Appetite and Nausea

Reduced appetite, nausea, and occasional vomiting can develop, particularly in acute infection.

Abdominal Discomfort

A dull ache or discomfort, usually in the upper right side of the abdomen, near the liver.

Dark Urine

A noticeable change in urine colour can be an early sign of liver involvement.

Jaundice

Yellowing of the skin or eyes usually appears later, once the liver is more significantly affected.

Danger Signs

Seek urgent medical attention if any of the following develop.

Yellowing of the Skin or Eyes That Is Worsening

Rapidly worsening jaundice can indicate the liver is struggling to keep up and needs urgent assessment.

Confusion or Difficulty Staying Alert

Can indicate the liver is no longer clearing toxins properly, a serious complication requiring emergency care.

Severe Abdominal Pain or Swelling

May indicate significant liver inflammation or fluid buildup and should be assessed promptly.

Easy Bruising or Bleeding

Can indicate the liver is struggling to produce proteins needed for normal blood clotting.

Diagnosis

Blood Test for Hepatitis B Surface Antigen (HBsAg)

The primary screening test. A positive result indicates a current infection, whether acute or chronic.

Additional Antibody Testing

Tests for other hepatitis B markers help determine whether an infection is new, ongoing, past, or whether someone is immune from vaccination.

Liver Function Tests

Blood tests that measure liver enzymes and function, helping assess how much the liver has been affected.
Important
Because hepatitis B often causes no symptoms, many people only discover they have it through routine screening, such as blood donation checks or testing during pregnancy, rather than because they felt unwell.

Laboratory Tests

Hepatitis B Surface Antigen (HBsAg)

A positive result confirms current infection with hepatitis B, whether acute or chronic.

Sample Venous blood
Time Same day to 48 hours

Hepatitis B Core Antibody (Anti-HBc)

Helps distinguish a new infection from a past or ongoing one, depending on which antibody type is present.

Sample Venous blood
Time 24–72 hours

Hepatitis B Surface Antibody (Anti-HBs)

Indicates immunity, either from a past infection that has cleared or from vaccination.

Sample Venous blood
Time 24–72 hours

HBV DNA (Viral Load)

Measures how much virus is actively present, which helps guide treatment decisions for chronic infection.

Sample Venous blood
Time 3–5 days

Laboratory Note

Hepatitis B testing usually involves a panel of several markers rather than a single test, since the combination of results is what actually shows whether an infection is new, ongoing, past, or whether someone is protected through vaccination.

Treatment

Supportive Care for Acute Infection

Most adults with acute hepatitis B recover fully on their own. Rest, good nutrition, and fluids support the body while it clears the virus, since there is no specific medicine for acute infection.

Route Oral
Duration Several weeks to months

Antiviral Medication for Chronic Infection

For chronic hepatitis B, antiviral medications can suppress the virus and reduce liver damage, though they are not typically a cure and are not needed by everyone with chronic infection.

Route Oral
Duration Often long-term or lifelong

Treatment Note

Whether treatment is needed, and what kind, depends heavily on factors like viral load and liver function, and how long someone has had the infection. This is a decision made with a doctor over time, not something with a single fixed answer.

Prevention

Get vaccinated

The hepatitis B vaccine is safe and more than 95 percent effective, and is recommended as part of routine childhood immunisation.

Ensure newborns receive the birth-dose vaccine

A dose given within 24 hours of birth is one of the most effective ways to prevent mother-to-child transmission, a major route of infection in high-burden regions.

Practise safe injection and blood safety measures

Avoiding the reuse of needles or syringes, and ensuring blood for transfusion is properly screened, prevents transmission.

Practise safer sex

Using condoms and knowing a partner’s hepatitis B status reduces the risk of sexual transmission.

Prevention Note

Because hepatitis B spreads most efficiently from mother to child around birth, and because infection at this age carries the highest risk of becoming lifelong, timely birth-dose vaccination is one of the single most impactful prevention measures available.

Risk Factors

Higher Risk of Chronic Infection

Age at infection is the strongest factor in whether hepatitis B becomes a lifelong infection.

  • Infants infected at birth, particularly from an infected mother
  • Children infected before the age of 5

Increased Chance of Infection

These groups have a higher chance of exposure to hepatitis B.

  • People born in or with family from regions where hepatitis B is common
  • Healthcare workers and others regularly exposed to blood
  • People with multiple sexual partners or a partner with hepatitis B

Exposure Factors

Situations that increase the risk of exposure.

  • Sharing needles or injection equipment
  • Receiving unscreened blood products or unsterile medical or dental procedures

Risk Note

Living in a region with a high burden of hepatitis B does not mean infection is inevitable. Vaccination remains highly effective at preventing infection regardless of local prevalence.

Complications

Cirrhosis

Long-term liver inflammation can lead to scarring of the liver, which impairs its ability to function.

Liver Cancer (Hepatocellular Carcinoma)

Chronic hepatitis B significantly increases the lifetime risk of liver cancer, even in people without cirrhosis.

Liver Failure

In severe cases, either acute or as an end stage of chronic disease, the liver can lose the ability to function, which is life-threatening.

Complication Note

Most complications develop over years or decades of chronic infection, which is why regular monitoring matters even when someone feels completely well.

When to Seek Medical Care

Yellowing of the Skin or Eyes

New or worsening jaundice should be assessed by a healthcare provider.

Confusion or Unusual Drowsiness

Can indicate the liver is struggling to clear toxins and needs urgent evaluation.

Severe Abdominal Pain or Swelling

May indicate significant liver involvement and should not be ignored.

Known Hepatitis B Exposure or Diagnosis Without Follow-Up Care

Anyone diagnosed with hepatitis B, or who has not been screened despite a known risk factor, should establish care with a doctor for ongoing monitoring.

Emergency Advice

Because hepatitis B often causes no symptoms for years, regular monitoring for those diagnosed matters just as much as recognising the warning signs above.

Prognosis

Excellent for Most Adults with Acute Infection

About 95 percent of adults who become infected clear the virus completely within months and do not develop chronic infection.

More Likely to Become Lifelong When Infection Happens Early

Around 90 percent of infants infected at birth, and 30 to 50 percent of children infected before age 5, go on to live with chronic hepatitis B.

Manageable With Long-Term Monitoring

For people with chronic hepatitis B, regular monitoring and, when needed, antiviral treatment can significantly reduce the risk of serious liver disease.

Prognosis Note

Hepatitis B is one of the clearest examples of why age at infection matters so much, which is exactly why preventing infection at birth and in early childhood is such a global public health priority.

Differential Diagnosis

Hepatitis A

Also causes liver inflammation and jaundice, but spreads through contaminated food or water rather than blood or body fluids, and does not become chronic.

Hepatitis C

Another blood-borne virus that can cause chronic liver infection, often distinguished from hepatitis B through specific blood testing.

Malaria

Severe malaria can also cause jaundice and abdominal symptoms in the same regions, and should be considered when hepatitis B testing is not yet available.

Clinical Note

Because several conditions can cause jaundice or liver-related symptoms, specific blood testing is needed to confirm hepatitis B rather than relying on symptoms alone.

References

World Health Organization (WHO)

World Health Organization fact sheet on hepatitis B transmission, symptoms, diagnosis, treatment, and prevention.

Centers for Disease Control and Prevention (CDC)

Public information on hepatitis B symptoms, spread, prevention, vaccination, and treatment.

CDC Clinical Overview of Hepatitis B

Clinical guidance for healthcare providers on hepatitis B risk factors, natural history, and chronic infection risk by age.

Frequently Asked Questions

Can hepatitis B be cured?
Acute hepatitis B usually clears on its own in adults. Chronic hepatitis B is generally not curable, but antiviral treatment and regular monitoring can control the virus and significantly reduce the risk of serious liver disease.
How is hepatitis B spread?
Mainly through contact with infected blood or body fluids, including from mother to child during birth, sexual contact, and sharing needles or unsterile medical equipment. It is not spread through casual contact, sharing food, or coughing.
Can I have hepatitis B without knowing it?
Yes. Many people, especially children, have no symptoms at all and only discover the infection through a blood test, such as routine screening or a check during pregnancy.
Is the hepatitis B vaccine safe?
Yes. It has been used safely for decades and is more than 95 percent effective at preventing infection.