Hepatitis B infection

Hepatitis B is a viral infection that causes inflammation of the liver.

Hepatitis B virus is spread through contact with blood or other body fluids of an infected person. The virus attacks the liver cells causing either short-term (acute) or long-term (chronic) hepatitis. 

  • Acute hepatitis causes noticeable symptoms from which people fully recover.
  • Chronic hepatitis symptoms are less noticeable and treatment is focused on preventing long-term liver damage and stopping the spread of the disease.

A hepatitis B vaccine has been available in NZ since the 1980s, greatly reducing the number of people with this disease. This is part of the childhood immunisation schedule in NZ and older children and adults can also be vaccinated. Read more.

How is hepatitis B spread?

Hepatitis B is spread through contact with blood or bodily fluids (such as saliva and semen) of an infected person. For example, it can be passed:

Symptoms can appear anywhere from 45 to 160 days (average about 120 days) after becoming infected.

What are the symptoms of hepatitis B infection?

Some people do not have any symptoms, but others can have symptoms such as:

  • feeling sick or vomiting
  • lack of appetite
  • flu-like symptoms, such as tiredness, general aches and pains or headaches
  • abdominal pain
  • clay-coloured bowel motions and or dark coloured urine
  • yellowing of the skin and eyes (known as jaundice).

Who is at risk of hepatitis B infection?

Anyone can get hepatitis B, but those most at risk are:

  • babies born to mothers who have hepatitis B
  • people with multiple sex partners
  • men who have sex with men
  • people with a sexually transmitted infection (STI)
  • people who inject illegal drugs
  • people who use unsterile equipment for tatooing
  • people who live with people who have an active hepatitis B infection
  • healthcare and public safety workers exposed to blood at work
  • haemodialysis patients
  • residents and staff of facilities for developmentally disabled people
  • travellers to regions with intermediate or high rates of hepatitis B
  • people who participate in contact sports where there is high risk of bleeding injury.

Children are at greater risk of chronic hepatitis.

Most people (99%) with chronic hepatitis B infection were infected as babies (from their mother at delivery) or young children (from playing with other children who have hepatitis B infection, or by close-contact with an older household member with chronic hepatitis B).

When young children and babies get infected, they do not tend to get sick but are at much higher risk of remaining a hepatitis B carrier and developing chronic infection later in life (life-long risks of cirrhosis, liver failure and liver cancer). For this reason, all infected children (and adults infected as children) require long-term follow-up.

When adults are infected, they usually become sick with acute hepatitis (jaundice, abdominal pain and vomiting), but are at much less risk of developing chronic hepatitis.

How is hepatitis B infection diagnosed?

Hepatitis B can be diagnosed with blood tests, to detect the presence of the hepatitis B virus or antibodies to the virus in blood. During the early stages of acute hepatitis B blood tests may show changes in your liver function.

If you are at higher risk of getting hepatitis B, get tested. If you are pregnant, you should also get tested.

How is hepatitis B infection treated?

For acute hepatitis B infection, most people manage with support from their family doctor. Hepatitis B immune globulin injection (a concentrated blood protein) can be given to help the body to develop antibodies that fight the hepatitis B virus. This may not stop the disease developing altogether, but it does increase the body's ability to fight the virus.

For chronic hepatitis B infection, a number of antiviral medications are needed. These help prevent complications such as cirrhosis, liver failure and liver cancer, and also help prevent the transmission of the disease to others. 

Read more about chronic hepatitis B infection

How can hepatitis B infection be prevented?


One of the most effective ways to avoid getting hepatitis B is get immunised with the hepatitis B vaccine.

  • This is part of the childhood immunisation schedule in NZ and consists of 3 injections over 3 to 6 months.
  • To be protected from hepatitis B, all babies should be vaccinated.
  • Older children, adults and travellers can also be vaccinated. Ask your doctor or nurse what is right for you.

Read more about Hepatitis B vaccination (Immunisation Advisory Centre)

Other effective ways to reduce your risk of developing hepatitis

  • Never share drug equipment with other drug users. This does not just apply to needles, but also syringes, spoons and filters as well as bank notes or straws to snort cocaine.
  • Do not share personal items such as toothbrushes and razors.
  • Use a condom during sex, including anal and oral sex.
  • Have an STI check before you have unprotected sex with a new partner
  • Limit your consumption of alcohol. Read more about safer alcohol limits.
  • Make sure any blood spills are cleaned up properly – the virus can live on  objects for 7 days or more. Even if you don’t see any blood, there  could be virus on an object.

Check before you have sex

To prevent the spread of hepatitis B and other sexually transmitted infectsions (STIs), it is a good idea to have an STI check before having unprotected sex with a new partner. 

If you are a carrier for hepatitis B and have a new sexual partner then they will be at risk of catching hepatitis B from you. They should be checked for immunity against hepatitis B (very likely if under 25 years as should be protected by vaccination at birth).

If your partner is not immune, then they can receive a free hepatitis B vaccination which will protect them from getting acute hepatitis B. After they have finished the course of vaccines (3 over 3-6 months), they should be tested for protective immunity against hepatitis B. Until then, you and your partner should use condoms to prevent hepatitis B infection.

Where do I go for a check-up?

Sexual health clinics have specialists who are experienced in the management and diagnosis of syphilis. Treatment is free and confidential and the people there can help with testing your sexual partners or family members. 

Find a sexual health clinic

Learn more

Hepatitis Foundation Freephone 0800 33 20 10. 
Recommendations for reducing risk of hepatitis  NHS Choices website

Credits: Hepatitis Foundation. Reviewed By: Health Navigator