Hepatitis B is a liver infection caused by the hepatitis B virus (HBV). For some people, it’s a short illness that clears up with no problems. For others, it can cause long-lasting disease and long-term liver problems.
How Do People Get Hepatitis B?
Most commonly, HBV spreads through:
sexual activity with an HBV-infected person
shared contaminated needles or syringes for injecting drugs
HBV-infected mothers to their newborn babies
In the United States, the most common way people get infected with HBV is through unprotected sex with someone who has the disease. People who share needles also are at risk because the needles often aren't sterilized.
How Do Acute Hepatitis B and Chronic Hepatitis B Differ?
Doctors refer to hepatitis (heh-puh-TYE-tus) B infections as either acute or chronic:
Acute hepatitis B is a short-term illness that happens within 6 months of when a person is exposed to the virus.
Chronic hepatitis B is when a person still has the virus in their body after 6 months. This means the virus stays in the body and can cause lifelong illness.
The younger someone is when infected, the greater their chances for developing chronic hepatitis B. About 90% of babies with HBV will develop a chronic infection. That risk drops to 6%–10% when someone over 5 years old is infected. Because of this, the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) recommend that all babies get the first dose of the hepatitis B vaccine within 12–24 hours of birth. They'll get two more doses later, at 1–2 months of age and at 6–18 months of age.
What Are the Signs & Symptoms of Acute Hepatitis B Infection?
HBV can cause a wide range of symptoms, from a mild illness and general feeling of being unwell to more serious chronic liver disease that can lead to liver cancer. Someone with acute hepatitis B may have symptoms similar to those caused by other viral infections, like the flu. They might:
HBV also can cause darker than usual pee, light or grey-colored stools (poop), jaundice (when the skin and whites of the eyes look yellow), joint pain, and belly pain.
People exposed to hepatitis B may start to have symptoms from 1 to 6 months later. Symptoms can last for weeks to months.
In some people, hepatitis B causes few or no symptoms. But even someone who has no symptoms can still spread the disease to others.
What Problems Can Hepatitis B Cause?
Chronic hepatitis B is a serious infection. It can lead to cirrhosis (permanent scarring) of the liver, liver failure, or liver cancer, which can cause severe illness and even death.
If a pregnant woman has hepatitis B, even with no symptoms, her baby has a very high chance of catching it at birth or just after, unless the baby gets a special immune injection and the first dose of hepatitis B vaccine shortly after birth.
Sometimes, HBV doesn't cause symptoms until a person has had the infection for a while. At that stage, they already might have more serious problems, such as liver damage.
How Is Hepatitis B Diagnosed?
Someone with symptoms or who might have been exposed to the virus through sex or drug use should see a doctor right away for a blood test that can show antibodies to the virus. The blood test also can tell whether someone has an acute infection or a chronic infection.
How Is Hepatitis B Treated?
There's no cure for hepatitis B. Doctors will offer advice on how to manage symptoms — like getting plenty of rest or drinking fluids. A person who is too sick to eat or drink will need treatment in a hospital.
In most cases, older kids and teens who get hepatitis B recover and may develop a natural immunity to future hepatitis B infections. Most feel better within 6 months. Health care providers will keep a close eye on patients who develop chronic hepatitis B, and sometimes will treat it with antiviral medicine.
What Happens After a Hepatitis B Infection?
Some people carry the virus in their bodies and are contagious for the rest of their lives. They should not drink alcohol, and should check with their doctor before taking any medicines (prescription, over-the-counter, or supplements) to make sure these won't cause more liver damage.
Anyone who has ever tested positive for hepatitis B cannot be a blood donor.
Can Hepatitis B Be Prevented?
Yes. Newborn babies in the United States now routinely get the hepatitis B vaccine as a series of three shots over a 6-month period. There's been a big drop in the number of cases of hepatitis B thanks to immunization.
Doctors also recommend "catch-up" vaccination for all kids and teens younger than 19 years old who didn't get the vaccine as babies or didn't get all three doses. Some kids may need to be revaccinated later in life. These include children:
whose mothers carry the hepatitis B virus in their blood
If someone who hasn't been vaccinated is exposed to HBV, doctors may give the vaccine and/or a shot of immune globulin containing antibodies against the virus to try to prevent infection. That's why it's very important to see a doctor right away after any possible exposure to the virus.
To prevent the spread of hepatitis B through infected blood and other body fluids, adults and teens should:
always use latex condoms when having sex (oral, vaginal, or anal)
avoid contact with an infected person's blood
not use intravenous drugs or share needles or other drug tools
not share things like toothbrushes or razors
research tattoo and piercing places carefully to be sure they don't reuse needles without properly sterilizing them