Hepatitis B surface antibody (anti-HBs)

A reactive or positive anti-HBs result can fit with immunity after vaccination or recovery from a past infection. This marker alone cannot tell those situations apart. A non-reactive result means the laboratory did not detect the antibody at its reporting threshold; it does not by itself prove that you have hepatitis B. Doctors interpret anti-HBs alongside other hepatitis B markers, your vaccination history, and any exposure history. See [Hepatitis B](/conditions/hepatitis-b/).

Take the complete report to the clinician who ordered it and ask which other markers were checked. If anti-HBs is not detected and you have no reliable vaccination history, the clinician may discuss [Hepatitis B Vaccination](/treatments/preventive-care-and-vaccination/hepatitis-b-vaccination/). If recent exposure or symptoms are part of the story, further blood tests may be needed. A [Liver Function Test](/treatments/diagnostics-and-screening/liver-function-test/) can assess liver inflammation but does not replace hepatitis B testing. Do not start or stop treatment based on anti-HBs alone.

Arrange prompt review for yellow skin or eyes, new dark urine, persistent vomiting, significant abdominal pain, or unusual sleepiness. Contact a healthcare service soon after a possible exposure because preventive care may be time-sensitive. Fatigue alone has many explanations, but ongoing or severe fatigue should still be assessed alongside the full clinical picture; read more about [Dark Urine](/symptoms/dark-urine/) and [Fatigue](/symptoms/fatigue/).

Ask whether your anti-HBs is reactive, which companion tests were performed, whether vaccination explains the result, and whether you need repeat testing. Ask how your result affects sexual or household contacts and whether liver tests or follow-up are appropriate.