What should you know about blood HBsAg test?

A positive result means the antigen was detected, but it does not by itself show how long infection has been present, how active it is, or whether liver damage exists. A negative result does not establish immunity; vaccination and other hepatitis B markers are assessed differently. Clinicians may request additional blood tests and review symptoms, vaccination history, exposure risks, and liver tests before explaining the result.

Attend follow-up even if you feel well because hepatitis B can cause few symptoms. Until your clinician explains the result, avoid sharing razors, toothbrushes, or items that may carry blood, and cover open cuts. Ask about testing and vaccination for household or sexual contacts. Do not stop prescribed medicines or donate blood based on a result without medical advice; specialist review may be appropriate when antigen is detected.

Seek urgent care for yellowing of the skin or eyes with severe illness, confusion, unusual sleepiness, vomiting that prevents drinking, severe abdominal pain, or bleeding. Contact your clinician soon about a positive result, pregnancy, a recent possible exposure, or symptoms such as dark urine, pale stools, nausea, or marked tiredness.

Ask which hepatitis B markers will be checked next, whether liver tests are needed, how to protect close contacts, and whether specialist follow-up or repeat testing is appropriate.