Hepatitis B and low immunity: what to know

A blood test may show that you do not have enough protective antibody, or that your immune system may respond less strongly because of illness or medicines. This result does not by itself prove that you have hepatitis B. A clinician may use several blood tests to distinguish current infection, past exposure and lack of protection. See the overview of [Hepatitis B](/conditions/hepatitis-b/) for context.

People with reduced immune function may need closer follow-up because infection can behave differently or remain unnoticed. Symptoms can be mild or absent; [Fatigue](/symptoms/fatigue/) and [Dark Urine](/symptoms/dark-urine/) should be reported rather than used to diagnose the cause.

Take your test report to a doctor and ask which markers were checked. Do not start, stop or repeat medicines without advice. If vaccination is appropriate, the clinician can choose a schedule and decide whether a later blood test is useful; read about [Hepatitis B Vaccination](/treatments/preventive-care-and-vaccination/hepatitis-b-vaccination/). A [Liver Function Test](/treatments/diagnostics-and-screening/liver-function-test/) may help monitor liver health, but it cannot replace hepatitis B testing.

Arrange prompt medical review for yellowing of the eyes or skin, worsening dark urine, repeated vomiting, severe abdominal pain, unusual sleepiness or confusion. Seek urgent help if confusion, collapse or difficulty staying awake develops. These signs need assessment even when a previous immunity result seemed reassuring.

Ask: Which result shows my level of protection? Do I need vaccination or repeat testing? Could a medicine or health condition affect my immune response? What follow-up is suitable for my liver?