What should you know about hepatitis B surface antigen?

A reactive or positive result suggests current hepatitis B infection, but it does not by itself show whether the infection is recent or long-standing, or how active it is. A non-reactive result means this marker was not detected; other blood markers may still be needed to understand immunity, past infection, or a very early infection. The result should be interpreted with the full panel and your health history.

Hepatitis B can affect the liver without causing obvious symptoms. When symptoms occur, they may include tiredness, nausea, discomfort under the ribs, or dark urine. Learn more about [Hepatitis B](/conditions/hepatitis-b/), [Fatigue](/symptoms/fatigue/), and [Dark Urine](/symptoms/dark-urine/).

Take the report to a clinician who can review the result alongside hepatitis B surface antibody and core antibody tests. Follow-up may include repeat testing, a [Liver Function Test](/treatments/diagnostics-and-screening/liver-function-test/), and sometimes testing for viral material. Until the result is clarified, avoid sharing razors or toothbrushes, cover open cuts, and ask about testing for household or sexual contacts. Do not stop prescribed medicines without advice. If you are not immune, ask whether [Hepatitis B Vaccination](/treatments/preventive-care-and-vaccination/hepatitis-b-vaccination/) is appropriate.

Arrange prompt medical review for a reactive result, especially during pregnancy or before starting treatment that may weaken the immune system. Seek urgent care for yellow eyes or skin, confusion, severe vomiting, marked sleepiness, bleeding, or severe abdominal swelling. These symptoms can signal significant liver illness and need assessment regardless of the test result.

Ask which hepatitis B markers were tested, whether the result needs confirmation, whether liver tests or monitoring are needed, and whether people close to you should be tested or vaccinated. Ask how to protect partners and family members while the result is being clarified.