Hepatitis B is a type of virus that can infect the liver. Many people don’t realise they have been infected with the virus because the symptoms may not develop immediately, or even at all.

It takes between 40 and 160 days for any symptoms to develop after exposure to the virus.

How does hepatitis B spread?

Hepatitis B can be spread through blood and body fluids such as semen and vaginal fluids, so it can be caught:
*during unprotected sex, including anal and oral sex
*by sharing needles to inject drugs such as heroin

Hepatitis B in pregnancy

A mother can also pass on the hepatitis B infection to her newborn baby, but the infection can be prevented if the baby is vaccinated immediately after birth.

In England, people who are most at risk of contracting hepatitis B include:
*people who inject drugs
*people who change sexual partners frequently

How is it diagnosed?

Hepatitis B is diagnosed by a blood test that shows a positive reaction to hepatitis B surface antigen (the outer surface of the hepatitis B virus that triggers a response from your immune system).
A positive result means your liver is releasing hepatitis B protein into your blood, which suggests chronic infection.
Your GP may also request a liver function test. This is a blood test that measures certain enzymes and proteins in your bloodstream, which indicates whether your liver is damaged. It will often show raised levels if you are infected with the hepatitis B virus.

Stages of infection

In most cases, the hepatitis B virus will only stay in the body for around one to three months. This is known as acute hepatitis B.
In around 1 in 20 cases in adults, the virus will stay for six months or longer, usually without causing any noticeable symptoms. This is known as chronic hepatitis B.
Chronic hepatitis B is particularly common in babies and young children: 9 in 10 children infected at birth and around 1 in 5 children infected in early childhood will develop a long-term infection.
People with chronic hepatitis B can still pass the virus on to other people, even if it is not causing any symptoms.
Around 20% of people with chronic hepatitis B will go on to develop scarring of the liver (cirrhosis), which can take 10 to 20 years to develop, and around 1 in 10 people with cirrhosis will develop liver cancer.

Who is affected?

Hepatitis B is uncommon in England and cases are largely confined to certain groups, such as drug users, men who have sex with men, and certain ethnic communities (for example, South Asian, African and Chinese). There were 5,478 newly reported cases in England during 2011.
In contrast, hepatitis B is common in other parts of the world, particularly east Asia and sub-Saharan Africa. The World Health Organization estimates that hepatitis B is responsible for 600,000 deaths a year worldwide.


The vast majority of people infected with hepatitis B are able to fight off the virus and fully recover from the infection within a couple of months.
Most people with chronic hepatitis B have very little liver damage. A small minority of people go on to develop cirrhosis of the liver and, in some cases, liver cancer.

It’s therefore important to get yourself vaccinated if you fall into one of the high-risk groups for catching hepatitis B.

Most people remain healthy without any symptoms while they fight off the virus. Some will not even know they have been infected.
However, until the virus has been cleared from their body, they can pass it on to others.
If there are any symptoms, these will develop on average 40 to 160 days after exposure to the virus and will usually pass within one to three months.
Symptoms of hepatitis B include:

  • flu-like symptoms, such as tiredness, general aches and pains, headaches and a high temperature of 38ºC (100.4ºF) or above
  • loss of appetite and weight loss
  • feeling sick
  • being sick
  • diarrhoea

Some people may experience more severe symptoms, including abdominal pain and yellowing of the skin and eyes (jaundice).
Jaundice happens because your damaged liver is unable to remove bilirubin, a yellow substance in the blood that is a by-product of red blood cells. Bilirubin may also turn your urine very dark, and you may have pale stools (faeces).

Chronic hepatitis B

Hepatitis B is said to be chronic when you have been infected for longer than six months.
The symptoms are usually much milder and tend to come and go. In many cases, people with chronic hepatitis B infection will not experience any noticeable symptoms.
However, without treatment, chronic hepatitis B can lead to more serious conditions such as liver disease (inflammation) or cirrhosis (scarring of the liver) in a small number of people.
Read more about complications of hepatitis B.

How is it treated?

If you are diagnosed with hepatitis B, it is likely that your GP or clinic will refer to you a specialist, usually a hepatologist (a liver specialist). Most people tend to be free of symptoms and recover completely within a couple of months, never going on to develop chronic hepatitis.

There is usually no specific treatment for acute (short-term) Hepatitis B. Unless your symptoms are particularly severe, you should be able to manage them at home.

You can take over-the-counter painkillers such as paracetamol and may be prescribed codeine if the pain is more severe. Nausea (feeling sick) can often be controlled with a medication called metoclopramide.
If you are diagnosed as having a hepatitis B infection, you will be advised to have regular blood tests and physical check-ups.

Once your symptoms get better, you will need further testing to check that you are free of the virus and have not developed chronic hepatitis B.

Treating chronic hepatitis B

If you have chronic hepatitis B, you will be symptom-free for much of the time. However, you may need to take medication to prevent liver damage, possibly for many years.
There are now very effective medications that can suppress the virus over many years. These can slow down the damage being done to the liver, allowing the body to repair itself. However, it is unusual for this treatment to clear the virus permanently.

You may also need regular tests to assess the state of your liver. This might include blood tests, an ultrasound or a FibroScan, which measures liver stiffness, and possibly a liver biopsy. This is to assess whether the virus is currently damaging the liver and how much damage has been done.
The medication used to treat chronic hepatitis B will depend on whether there is evidence of ongoing liver damage. In some patients, their immune system suppresses the virus without causing damage.
If your liver is shown to be working fairly well, the first treatment offered will be a drug called peginterferon alfa 2-a.

Depending on the results of monitoring tests, you may need to take different medication at a later date. If your liver is showing signs of failing, or peginterferon alpha-2a is not suitable or not working for you, your doctor is likely to offer antiviral medication. This is usually tenofovir or entecavir.
In some cases, treatment works well and it is possible for your immune system to regain control over hepatitis B. In this case your doctor may advise you to stop taking medication altogether.
It is very important that you take your treatment as prescribed, even if you feel well or are finding side effects troublesome, as stopping treatment early can lead to drug resistance and could also lead to liver damage. Always speak to your doctor before you come off these drugs.

Peginterferon alfa-2a

Peginterferon alfa-2a can be used in the treatment of hepatitis B where there are very high levels of the virus. It stimulates the immune system (the body’s defence against infection) to attack the hepatitis B virus and regain control over it.

The medication is usually given by injection once a week over 12 months. Your doctor will be able to tell whether the treatment is likely to work for you during tests at three and six months. They may suggest an alternative antiviral if the treatment is not working.

It’s common to experience flu-like symptoms such as a high temperature and muscle and joint pain after beginning to take peginterferon alfa-2a. Taking paracetamol can often help relieve these side effects and they should get better with time.

However, in some people peginterferon alfa-2a can cause a wide range of persistent and unpleasant side effects. This may mean that treatment needs to be withdrawn and an alternative antiviral will need to be used.

If you start to feel any uncomfortable side effects, discuss this with your doctor or nurse.


Tenofovir is available in tablet form and should usually be taken with food.
Side effects of tenofovir include:

  • diarrhoea
  • feeling sick
  • being sick
  • skin rash
  • feeling weak
  • dizziness
  • in rare cases, kidney problems


Entecavir is available as a tablet.
Side effects of entecavir include:

  • being sick
  • feeling sick
  • insomnia
  • dizziness
    If you feel dizzy, avoid driving or using tools or machinery.

Lactic acidosis

A rare but serious side effect that can occur with tenofovir and entecavir is that the medication can cause a build-up of lactic acid in your blood. This is known as lactic acidosis and is potentially serious if left untreated.
Initial warning signs and symptoms of lactic acidosis include:

  • feeling very weak or tired
  • having unusual muscle pain
  • breathing difficulties
  • having stomach pain, along with feeling or being sick
  • feeling unusually cold, especially in your arms and legs
  • feeling dizzy or lightheaded
  • having a fast or irregular heartbeat
    If you experience any of these warning signs and symptoms, contact the doctor in charge of your care for advice.

Can it be prevented?

There is a vaccine thought to be 95% effective in preventing hepatitis B. Because of the relative rarity of hepatitis B in England, the vaccine is not given as part of the routine childhood vaccination schedule.

Vaccination would usually only be recommended for people in high-risk groups, such as:
*people who inject drugs or have a sexual partner who injects drugs
*people who change their sexual partner frequently
*people travelling to or from a part of the world where hepatitis B is widespread
*healthcare workers who may have come into contact with the virus
*Pregnant women are also screened for hepatitis B. If they are infected, their baby can be vaccinated shortly after birth to prevent them also becoming infected.