Hepatitis B

Hepatitis B is a viral infection that causes liver inflammation and can manifest as either a short-term acute illness or a long-term chronic condition. An estimated 640,000 people in the United States are living with chronic hepatitis B. While many people associate the infection with severe symptoms, the reality is often different: many carriers have no symptoms at all, which is why the condition can go undiagnosed for years.

The outcome of hepatitis B infection depends heavily on the age at which infection occurs. Most adults who contract the virus develop an acute infection and recover fully, even when symptoms are severe: approximately 95% of adults clear the infection completely. However, the younger the individual at the time of infection, the higher the risk of chronic disease. Roughly 90% of infected infants and 30% of children infected between ages one and five develop chronic infection. For those with chronic hepatitis B, ongoing monitoring and sometimes antiviral treatment are necessary to prevent serious complications including cirrhosis and liver cancer.

Hepatitis B spreads when blood, semen, or other infectious body fluids from an infected person enter the body of someone who is not infected, even in very small quantities. The most common transmission routes include sexual contact, sharing needles or syringes, and mother-to-child transmission during birth. In the United States, injection drug use is the leading risk factor among newly infected individuals, followed by having multiple sexual partners.

Other risk factors include living in the same household as someone with hepatitis B, being born in a country with high hepatitis B prevalence, occupational blood exposure in healthcare settings, men who have sex with men, dialysis patients, and individuals with HIV. The virus can also spread through sharing personal items that may carry traces of blood, such as razors or toothbrushes. People with diabetes may face increased risk through shared blood glucose monitoring equipment.

The CDC recommends that all adults undergo hepatitis B screening at least once in their lifetime. Testing is particularly important for individuals with risk factors such as a history of injection drug use, multiple sexual partners, birth in a region with high hepatitis B prevalence, or close contact with someone known to be infected. Anyone who knows or suspects they have been exposed should contact a healthcare provider promptly, as preventive treatment administered within 24 hours of exposure may reduce infection risk.

When symptoms of acute hepatitis B do appear, they typically emerge an average of 90 days after exposure (range: 60 to 150 days). Since many people with hepatitis B experience no symptoms, testing is the only reliable method for confirming infection status. Testing may also be recommended for pregnant individuals, healthcare workers, and anyone planning travel to areas where hepatitis B is prevalent.

A positive (reactive) HBsAg result indicates current hepatitis B infection. Additional testing may be needed to determine whether the infection is acute (recently acquired) or chronic (long-standing). A negative HBsAg result generally means no current infection, though a brief window period early after exposure can produce a falsely negative result.

Liver function tests help assess whether the infection is actively damaging the liver. Some individuals with chronic hepatitis B develop elevated liver enzymes, cirrhosis, or liver cancer, while others show no evidence of liver injury despite carrying the virus. Elevated liver enzymes may suggest active inflammation, but normal enzyme levels do not rule out infection. The combination of surface antigen, surface antibody, and core antibody results together provides a complete picture of infection status, immunity, and exposure history. Healthcare providers interpret these results in context to determine appropriate monitoring and treatment.

Vaccination is the most effective prevention measure for hepatitis B and is recommended for most people. For individuals already living with hepatitis B, certain lifestyle practices help protect liver health and reduce transmission risk. Avoiding alcohol is important, as alcohol accelerates liver damage in the setting of hepatitis B. A healthy diet supports overall liver function.

Practicing safe sex and ensuring partners are tested and vaccinated helps prevent sexual transmission. Individuals who inject drugs should use clean needles and equipment. Sharing personal items that might carry traces of blood, such as razors and toothbrushes, should be avoided. Regular medical monitoring is important for people with chronic hepatitis B to track liver health, detect complications early, and determine whether antiviral treatment is indicated.