Causes of hepatitis B 

You can become infected with hepatitis B if you are not immune (resistant) to the virus and you come into contact with the blood or body fluids of an infected person.

Many people with hepatitis B do not know they are infected.

The risk of hepatitis B for tourists is considered to be low. However, this risk will increase with certain activities, such as unprotected sex or receiving medical or dental treatment in a developing country.

Travellers are advised to get vaccinated against hepatitis B before visiting any country where this is a problem. Read more information about the hepatitis B vaccination.

Exposure to infected blood

You are at risk of catching hepatitis B if you:

  • inject drugs and share needles and other equipment, such as spoons and filters, or you are having a sexual relationship with someone who injects drugs
  • have an open wound, cut or scratch and come into contact with the blood of someone with hepatitis B
  • have medical or dental treatment in a country where equipment is not sterilised properly
  • work closely with blood – for example, healthcare workers and laboratory technicians are at increased risk of injury when the skin is accidentally punctured by a used needle
  • have a blood transfusion in a country where blood is not tested for hepatitis B
  • have a tattoo or body piercing in an unsafe, unlicensed place – read more about the risks of body piercing
  • share toothbrushes, razors and towels that are contaminated with infected blood

All blood donations in the UK are tested for hepatitis B.

Exposure to infected body fluids

You are at risk of catching hepatitis B if you have sex with an infected person without using a condom.

Generally, your risk increases if you are sexually active and have unprotected sex with several different partners. This includes unprotected anal and oral sex.

Commercial sex workers (both women and men) also have an increased risk of contracting hepatitis B.

Geographical risks

You also have an increased risk if you or your sexual partner grew up, lived or worked in a part of the world where hepatitis B is relatively common.

Hepatitis B is most common in:

  • sub-Saharan Africa
  • east and southeast Asia
  • the Middle East
  • southern and eastern Europe

Hepatitis B and pregnancy

Mothers with hepatitis B can pass the virus to their babies during pregnancy or when giving birth.

All pregnant women in the UK are therefore offered a blood test to check if they have hepatitis B. If they are infected, the baby is vaccinated immediately after birth to help prevent infection developing.

A mother with hepatitis B can breastfeed her baby if the baby receives a vaccine course starting at birth.

Page last reviewed: 02/06/2014

Next review due: 02/06/2016