Hepatitis B (Hep B) is an infection of your liver. It can cause scarring of the organ, liver failure, and cancer. It can be fatal if it isn’t treated. It’s spread when people come in contact with the blood, open sores, or body fluids of someone who has the hepatitis B virus. It’s serious, but if you get the disease as an adult, it shouldn’t last a long time. Your body fights it off within a few months, and you’re immune for the rest of your life. That means you can’t get it again. But if you get it at birth, it’ unlikely to go away.