What should you know about HBsAg and hepatitis B?

Your clinician interprets HBsAg alongside other hepatitis B markers, liver blood tests and your medical history. A negative result means HBsAg was not detected in that sample, although timing and other markers may still matter. Some people have no symptoms, while others notice fatigue, nausea, discomfort under the ribs or dark urine. Read more about [Hepatitis B](/conditions/hepatitis-b/), [Fatigue](/symptoms/fatigue/) and [Dark Urine](/symptoms/dark-urine/).

Arrange a follow-up appointment if the result is positive or unclear. Ask which confirmatory tests are needed, whether your liver should be assessed with a [Liver Function Test](/treatments/diagnostics-and-screening/liver-function-test/), and whether household or sexual contacts need testing or [Hepatitis B Vaccination](/treatments/preventive-care-and-vaccination/hepatitis-b-vaccination/). Do not stop prescribed medicines without advice, and avoid sharing razors, toothbrushes or needles.

Seek urgent medical help for yellowing of the skin or eyes, confusion, severe vomiting, marked sleepiness, bleeding, or rapidly worsening abdominal swelling. Contact a clinician soon about new dark urine, pale stools or unusual fatigue, especially after a positive result or possible exposure.

Ask: Is HBsAg positive, negative or indeterminate? Which other markers and liver tests are needed? Could this be a recent infection or a long-term infection? Should anyone close to me be tested or vaccinated? When should my result be reviewed?