What should you know about hepatitis B surface antigen reactive?

Reactive means the surface antigen was detected. It can be seen with a recent infection or a longer-lasting infection, and this single result does not establish which situation applies. Confirmation and other markers help clinicians assess the timing, activity, liver health, and need for monitoring or treatment.

Some people with hepatitis B have no symptoms. Others may notice fatigue, nausea, discomfort in the upper abdomen, or dark urine. A reactive result is about the virus marker; it does not predict how you feel. See [Hepatitis B](/conditions/hepatitis-b/), [Fatigue](/symptoms/fatigue/), and [Dark Urine](/symptoms/dark-urine/).

Book a medical appointment promptly and bring the complete report, vaccination history, medicines, and details of any possible exposure. Your clinician may repeat or confirm the test, order other hepatitis B markers and a [Liver Function Test](/treatments/diagnostics-and-screening/liver-function-test/), and discuss monitoring or treatment. Until reviewed, do not share razors, toothbrushes, or injection equipment; cover cuts and ask about testing and vaccination for household or sexual contacts. [Hepatitis B Vaccination](/treatments/preventive-care-and-vaccination/hepatitis-b-vaccination/) protects people who are not immune, but it does not treat an existing infection.

Seek urgent care for yellow skin or eyes, confusion, severe vomiting, unusual bleeding, severe drowsiness, or marked abdominal swelling. Contact a clinician quickly if you are pregnant or about to start medicine that suppresses the immune system, because the result changes the care plan.

Ask whether the result will be confirmed, which other markers are needed, whether your liver needs monitoring, and how to reduce transmission at home. Ask when contacts should be tested or vaccinated and what symptoms should trigger immediate help.