What hepatitis B is
The liver filters the blood, makes proteins (such as albumin and the clotting factors), processes fats and medicines and produces bile. The hepatitis B virus (HBV) infects liver cells and, as the immune system responds to them, causes inflammation. If the inflammation lasts for years, normal tissue is gradually replaced by scar tissue (fibrosis), which in its advanced stage is called cirrhosis.
Two forms are distinguished:
- Acute hepatitis B: a new infection lasting up to 6 months. Most adults clear the virus on their own and acquire lifelong immunity.
- Chronic hepatitis B: the virus stays in the body for more than 6 months. The risk of becoming chronic depends strongly on the age at infection: it is very high when the infection is acquired in infancy or early childhood and low when acquired in adulthood.
The course varies greatly from person to person. Some patients with chronic hepatitis have a “quiet” infection with little inflammation and need no medicines; others have active inflammation that should be treated. Only medical assessment can tell.
How it spreads and how it does not
HBV is found in blood and other body fluids. It spreads:
- through blood: unsterilized needles and instruments, tattoos and piercings done in unsafe conditions, shared razors and toothbrushes, direct contact with infected blood;
- through unprotected sex;
- from mother to baby, mainly during birth. This is the most important route worldwide, because infected babies more often develop chronic infection.
Hepatitis B is not spread by hugging, cheek kisses, handshakes, shared food or glasses, coughing or ordinary social contact. People with hepatitis B should not be isolated at home, at work or at school.
Symptoms
Many people have no complaints and find out by chance from a blood test. When symptoms occur, they include fatigue, nausea, loss of appetite, dark urine, pale stools and yellowing of the eyes and skin (jaundice). In acute hepatitis the symptoms can be more marked; in chronic hepatitis they may be absent for decades.
The absence of symptoms does not mean the liver is not being damaged. That is why testing matters for people at risk: family members of a person with hepatitis B, people born to a mother with hepatitis B, people with frequent or unsafe exposure to blood, sexual partners of people with the infection, and people about to receive immunosuppressive drugs or chemotherapy.
Tests: how they are read
The diagnosis is made with blood tests called markers. They are always read together, not one by one:
| Marker | What it shows |
|---|---|
| HBsAg | Infection present (acute or chronic) |
| Anti-HBs | Immunity: from vaccination or from a resolved infection |
| Total anti-HBc | Contact with the virus, current or past (vaccination does not make it positive) |
| IgM anti-HBc | Suggests a new infection, but may also be positive in a flare of chronic infection |
| HBV-DNA | The amount of virus in the blood |
A positive HBsAg for more than 6 months indicates chronic infection. The full assessment also includes ALT/AST (see elevated transaminases), HBeAg, abdominal ultrasound and, when needed, assessment of fibrosis with blood scores or elastography. This assessment shows which phase the infection is in and whether treatment is needed now or only follow-up.
Treatment and follow-up
- Uncomplicated acute hepatitis is treated with supportive care: rest, hydration, avoiding alcohol and medicines that burden the liver. Severe forms need hospital admission.
- Chronic hepatitis: not every patient needs medicines right away. The decision depends on the amount of virus (HBV-DNA), ALT levels, the degree of fibrosis, age, a family history of liver cancer and other conditions. When treatment is indicated, antiviral tablets such as tenofovir or entecavir are used; they suppress the virus and lower the risk of complications. They are usually taken for a long time, sometimes without a set end date.
- Never stop the medicines on your own. Sudden discontinuation can cause a severe flare of hepatitis.
- Patients without an indication for medicines need regular check-ups (blood tests and ultrasound), because the phase of infection can change.
- Cirrhosis or high risk: abdominal ultrasound every 6 months is part of follow-up to detect liver cancer early, even when the virus is controlled with medicines.
A special situation is reactivation of the virus in people receiving chemotherapy, immunosuppressive drugs or biologics. That is why testing for hepatitis B (HBsAg and anti-HBc) should be done before these treatments start, even when the patient has no symptoms.
Prevention and protecting the family
The vaccine prevents hepatitis B very effectively. The standard schedule has three doses (at 0, 1 and 6 months) and is recommended for all children, for unvaccinated adults and especially for household contacts of people with the infection and for health care workers.
- Household contacts and partners should be tested and, if they are not infected or immune, vaccinated.
- Pregnancy: pregnant women are tested for HBsAg. Babies born to a mother with hepatitis B receive the vaccine and, when indicated, specific immune globulin right after birth (within 12 hours), which prevents infection in most cases. In some cases the doctor also proposes an antiviral for the mother in the last trimester.
- Do not share razors, toothbrushes or needles; use a condom if the partner is not immune.
- Alcohol speeds up liver damage; avoiding it or strictly limiting it is part of treatment.
- Discuss any medicine, herbal product or supplement with your doctor before using it.
Key sources
This information is educational and does not replace a visit to the doctor. Do not change your treatment without consulting your doctor. Updated: October 2026.