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

Without treatment, about a third of people with chronic hepatitis B infection go on to develop a disease of the liver, which can be very serious.

It is estimated that 15-25% of people with untreated chronic hepatitis B die of liver disease.

Cirrhosis

Scarring of the liver (cirrhosis) affects around one in five people with chronic hepatitis B, often many years after they first contracted the infection.

Cirrhosis doesn’t usually cause any noticeable symptoms until extensive damage to the liver has occurred. It can then trigger symptoms such as:

• tiredness and weakness
• loss of appetite
• weight loss
• feeling sick
• very itchy skin
• tenderness or pain around the liver
• swelling of the abdomen
• swelling of the ankles

If you do develop cirrhosis, it is important to prevent it getting worse by avoiding drinking any alcohol, which has a damaging effect on the liver.

There are range of treatments that can sometimes relieve some of the symptoms of cirrhosis. Antiviral medication may help prevent further damage. However, for some people the only option is a liver transplant.

Read more about the treatment of cirrhosis.

Liver cancer

Around 1 in 10 people with cirrhosis caused by chronic hepatitis B will go on to develop liver cancer.

Symptoms of liver cancer include:

• unexplained weight loss
• being sick
• feeling sick
• jaundice 

Read more about the treatment of liver cancer.

Fulminant hepatitis B

An uncommon and serious complication of acute hepatitis B is known as fulminant hepatitis B, where the immune system attacks the liver and causes extensive damage to it.

Fulminant hepatitis B occurs in around 1 in 100 adults with chronic hepatitis B, but is much rarer in children.

It can lead to symptoms such as:

• mental confusion
• swelling of the abdomen caused by a build-up of fluid
• jaundice

This complication is a medical emergency and 7 out of 10 people will die from it.

Hepatitis B is a type of virus that can infect the liver.

Symptoms can include:

• feeling sick
• being sick
• lack of appetite
• flu-like symptoms, such as tiredness, general aches and pains, and headaches
• yellowing of the skin and eyes (jaundice)

However, 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.

Read more about the symptoms of hepatitis B.

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.

Read more about hepatitis B in pregnancy.

In England, people who are most at risk of contracting hepatitis B include:

• people who inject drugs
• people who change sexual partners frequently

Read more about the causes and risk factors for the hepatitis B infection.

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.

Read more about complications of hepatitis B.

How is it treated?

There is currently no specific treatment for acute hepatitis B, other than using painkillers to relieve symptoms.

Treatment for chronic hepatitis B depends on how badly your liver is affected. It can be treated using medications designed to slow the production of the virus and prevent damage to the liver.

Read more about the treatment of hepatitis B.

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.

Read more about hepatitis B vaccination.

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.

Outlook

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.

The Map of Medicine is used by doctors throughout the NHS to determine the best treatment options for their patients. NHS Choices offers everyone in England exclusive and free access to this cutting-edge internet resource, which lets you see exactly what your doctor sees.

The information in the Map has been approved by the UK’s leading clinical experts, is based on the best available clinical evidence, and is continually updated. To take advantage of this unique resource go to:

Map of Medicine: Post exposure

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.

When to seek medical advice

Always make an appointment to see your GP if you have unusual symptoms that persist for more than a few days. Ask your GP for a hepatitis B test if you think you may have been exposed to hepatitis B in the past.

When to seek immediate medical advice

If you suspect that you have been recently exposed to the hepatitis B virus, seek immediate medical advice.

It is possible to prevent infection with treatment, but to be most effective it should be given in the first 48 hours after exposure (although it can sometimes be effective up to a week after exposure).

Phone your GP as soon as possible. If this is not possible, telephone NHS 111 or your local out-of-hours service for advice.

If you are diagnosed with hepatitis B, it is likely that your GP 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

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

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.

Preventing the spread of hepatitis B

While the medications mentioned above can slow the spread of chronic hepatitis B and hopefully prevent complications such as cirrhosis, they cannot cure the infection. This means you can still pass hepatitis B on to other people.

You should avoid having unprotected sex with someone, including anal and oral sex, unless you are sure they are immunised against hepatitis B.

If you are an injecting drug user, never share your needles or other injecting or preparation equipment with other drug users.

You should also take some sensible precautions to avoid the spread of infection, such not sharing toothbrushes or razors with other people.

Read more about preventing hepatitis B.