What is Hepatitis B?

What is Hepatitis B?

Hepatitis B, also known as hep B, is a liver infection caused by the hepatitis B virus (HBV). Two billion people have been infected with the hepatitis B virus, making it the most common cause of hepatitis worldwide. Sometimes the virus causes a long-term infection called chronic hepatitis B. Babies and young children with hepatitis B are more likely to have a chronic infection.

About 300 million people infected with HBV are living with a chronic hepatitis B infection. Chronic HBV can lead to cirrhosis (scarring of the liver), liver cancer, liver failure, and death, especially if left untreated.

Types of Hepatitis B


You are more likely to develop either acute or chronic HBV depending on your age. If you get the disease as an adult, your body is more likely to fight off the infection within a few months. But if you get it at birth, it’s unlikely to go away.

The two types of hepatitis B are:

  • Acute hepatitis B is a short-term illness that appears the first 6 months after someone is exposed to the hepatitis B virus. Some people with acute hepatitis B have no symptoms at all or only mild flu symptoms. Occasionally, acute hepatitis B can require hospitalization. If your body fights off the infection within those first few months, you will become immune. This means you will not be able to contract HBV again for the rest of your life.
  • Chronic hepatitis B is a long-term HBV infection, meaning the virus is still found in the blood after six months. About 9 in 10 babies who are infected develop life-long, chronic HBV. The risk of developing chronic HBV goes down as a child gets older. Chronic hepatitis B requires treatment and can lead to severe liver damage or liver cancer.

Reactivated hepatitis B

Reactivation is the sudden increase or reappearance of the hepatitis B virus. Antiviral treatments can’t destroy the DNA, or genetic information, that makes up hepatitis B. That means even after recovering from a past infection, the virus may still be inactive in the cells and reappear. It is not totally understood why this happens, but certain factors may increase a person’s risk of HBV reactivation.

Risk factors for reactivated hepatitis B:

  • Co-infection with other viruses such as hepatitis C
  • Older age
  • Biological males
  • Medications that affect the immune system (treatment for rheumatoid arthritis, other autoimmune diseases, or cancer)

Signs & Symptoms of Hepatitis B


The symptoms of hepatitis B vary from person to person, ranging from mild to severe. About one-third of those infected with HBV have no symptoms.

Symptoms from acute HBV usually start to go away in 2 to 3 weeks and may include:

  • Fever
  • Fatigue (feeling weak or tired)
  • Loss of appetite
  • Nausea
  • Vomiting
  • Abdominal pain
  • Dark urine
  • Clay-colored bowel movements
  • Joint pain
  • Jaundice (yellow color in the skin or the eyes)

Symptoms of chronic hepatitis B can appear the same as an acute infection, but many patients have no symptoms until they are diagnosed with cirrhosis or end-stage liver disease.

Symptoms of end-stage liver disease are:

  • Swelling of the legs and abdomen
  • Weight loss
  • Itchy skin
  • Frequent hiccups
  • Diarrhea
  • Confusion or disorientation

NewYork-Presbyterian’s liver specialists are experts in the care of people with hepatitis B, offering the latest medications and monitoring techniques. We are experienced in liver transplantation for people whose hepatitis B becomes life-threatening, with more clinical experience caring for these patients than most hospitals.

What Causes Hepatitis B?


Hepatitis B is spread when people come in contact with the blood, open sores, or other body fluids of someone who is infected with the HBV virus. The hepatitis B virus can survive outside the body for 7 days. During those 7 days, the virus can still cause infection. All patients who are not chronically infected will no longer be contagious 15 weeks after symptoms appear.

Causes of hepatitis B are:

  • Childbirth (when a mother with HBV transmits the virus to her baby)
  • Sex with an infected partner
  • Sharing needles or syringes
  • Sharing items such as razors or toothbrushes with someone who has HBV
  • Direct contact with the blood of an HBV-infected person
  • Exposure to the blood of an infected person through needlesticks or other sharp instruments

Risk Factors

Risk Factors

In the United States, rates of new HBV infections are highest among adults aged 30-59 years. Your risk of HBV infection increases if you:

  • Have unprotected sex with multiple sex partners
  • Have unprotected sex with someone who’s infected with HBV
  • Are pregnant
  • Use IV drugs or share needles during drug use
  • Are a man who has sex with other men
  • Live with someone who has a chronic infection
  • Are a baby born to an infected mother
  • Have a job that exposes you to human blood
  • Travel or live in areas with high infection rates of HBV, such as Asia, the Pacific Islands, Africa or Eastern Europe
  • Are an inmate or staff member of a correctional facility



Although most people with chronic hepatitis B don’t have any symptoms, some patients can have serious complications. Untreated or chronic hepatitis B can lead to:



The best way to prevent getting infected with hepatitis B is to get the HBV vaccine. The vaccine requires 2 to 4 injections over six months. It is recommended for newborns, children, adolescents, healthcare workers, and people with chronic liver disease.

To protect yourself from getting hepatitis B:

  • Get the hepatitis B vaccine (if you haven’t already been infected)
  • Use condoms every time you have sex
  • Wear gloves when you clean up after others, especially if you have to touch items that could have body fluids on them (bandages, tampons, or linens)
  • Cover all open cuts or wounds
  • Don’t share razors, toothbrushes, nail care tools, or pierced jewelry such as earrings
  • Ensure any needles for drugs, ear piercing, or tattoos are properly sterilized
  • Clean up blood with one part household bleach and 10 parts of water
Get Care

Trust NewYork-Presbyterian for Hepatitis B Care

From prevention and diagnosis to treatment and monitoring, NewYork-Presbyterian provides full-service care for people with acute or chronic hepatitis B. We assemble a team of liver care experts individualized for your needs, including hepatologists (liver doctors), gastroenterologists, surgeons, physician assistants, nurses, social workers, and others with experience treating HBV and other liver disorders. All of the healthcare providers you need are available to you, in one medical center.

Contact us to make an appointment and learn more about how we can help you.