Hepatitis B is caused by the hepatitis B virus (HBV), which spreads when infected blood or certain body fluids enter another person’s bloodstream.

What Hep B Is

  • Hepatitis B is a viral infection that mainly attacks the liver and is caused specifically by the hepatitis B virus (HBV), a DNA virus in the Hepadnaviridae family.
  • Once it enters the body, HBV travels through the blood to the liver, infects liver cells, and can cause both short-term (acute) and long-term (chronic) inflammation.

Main Ways It Spreads

Hep B does not spread through casual contact, food, water, sneezing, or coughing; it needs blood or certain body fluids to get into your body.

Common transmission routes include:

  • Unprotected sex with someone who has hepatitis B (blood, semen, vaginal fluids, and sometimes saliva can transmit the virus).
  • Sharing needles or syringes for injecting drugs; using unsterile equipment for tattoos or piercings.
  • Sharing items that may have tiny amounts of blood on them, such as razors, toothbrushes, or nail clippers.
  • Medical or cosmetic procedures done with instruments that are not properly sterilized.
  • From an infected mother to her baby during childbirth (called vertical or perinatal transmission).
  • Less commonly, bites that break the skin from someone who is infected.

Who Is at Higher Risk

Certain situations make it more likely to catch HBV because they increase exposure to blood or body fluids.

Higher-risk groups include:

  • People who have sex without condoms, especially with multiple partners or with a known infected partner.
  • People who inject drugs and share needles or other injection equipment.
  • Men who have sex with men.
  • Babies born to mothers who have hepatitis B.
  • People living in the same household as someone with chronic hepatitis B, especially if they share personal items.
  • Health care workers and others whose jobs expose them to blood (e.g., needlestick injuries).
  • People on hemodialysis, those who receive frequent blood products, or those in prisons or other institutional settings.
  • Travelers to regions where hepatitis B is very common (much of Asia, the Pacific Islands, Africa, and parts of Eastern Europe).

What Does Not Cause Hep B

  • You do not get hepatitis B from hugging, shaking hands, sharing food or water, or sitting next to someone with the infection.
  • It is not caused by stress, diet, alcohol alone, or casual social contact, though alcohol can worsen liver damage if someone already has hepatitis B.

Big Picture: Why Cause Matters

  • Knowing what causes hep B is crucial because there is a very effective vaccine that prevents infection and is recommended worldwide for infants and at-risk adults.
  • Understanding that it is blood/body-fluid transmitted helps focus on real prevention steps: vaccination, condoms, not sharing needles, and using sterile equipment for medical, dental, tattoo, or piercing procedures.

Information gathered from public forums or data available on the internet and portrayed here.