Hepatitis B has a long window: HBsAg, the marker of active infection, usually becomes detectable within several weeks of exposure, but symptoms average about 90 days out (range 60–150 days) CDC. For a reliable result, test about a month after a known exposure and confirm again a few months later if early results are negative.
treatable, not curable
testing, not symptoms, decides
| Item | Value |
|---|---|
| Curable? | managed — treatable, not curable |
| Tested by | exam + lab |
| Often | no symptoms |
| If you may have it | get tested — testing, not symptoms, decides |
How hepatitis B is tested
Hepatitis B is diagnosed with a blood test, not a urine cup or swab. The standard screen is a triple serologic panel that reads three markers at once CDC testing:
- HBsAg (hepatitis B surface antigen) — a piece of the virus's outer coat. If it's present, you have an active infection, whether brand-new or long-standing.
- Anti-HBs (antibody to surface antigen) — your body's protective response. It shows up after you clear the virus or after vaccination, and it means you're immune.
- Total anti-HBc (antibody to the core protein) — a fingerprint of past or current natural infection. The vaccine doesn't trigger it, so this marker separates a vaccinated person from someone who's met the virus.
The sample is a simple blood draw, and the lab runs all three markers together so a clinician can read them as a pattern. For how the full pattern fits together, see our guide on testing windows for blood-borne and sexually transmitted infections at when to test after exposure.
When to test after exposure: the window period
The hepatitis B window is the gap between exposure and the point when a test can actually pick up the infection. HBV replicates slowly compared with many viruses, so HBsAg takes time to climb high enough to register. Average time from exposure to symptoms is about 90 days, with a range of 60–150 days, and HBsAg generally becomes detectable in the blood before symptoms begin.
What that means in practice after a worrying exposure:
- A test in the first couple of weeks can miss an early infection, since HBsAg may not have risen yet.
- Testing about a month out catches most infections that are going to turn positive.
- If your early result is negative and you had a real exposure, repeat the test a few months later to be sure you've cleared the window entirely.
- If you were exposed recently, ask a clinician quickly about post-exposure options (vaccine, and sometimes immune globulin). These work best given early rather than after weeks of waiting.
A single early negative isn't a final answer for hepatitis B the way it might feel for a faster infection. The long incubation is why a follow-up test matters.
Who should get screened
As of the latest guidance, the CDC recommends screening every adult aged 18 and older at least once in their lifetime, regardless of risk, and screening pregnant people during each pregnancy CDC, 2023. Universal adult screening exists because hundreds of thousands of people live with undiagnosed chronic hepatitis B while reported acute cases have held roughly steady at about 2,200 a year (2020–2023) CDC surveillance. Most chronic infections are silent.
Test sooner and more often if any of these apply:
- You had a possible exposure to blood or to a partner's body fluids, or a partner tested positive.
- You're pregnant — every pregnancy is screened for HBsAg, because hepatitis B can pass to the baby around the time of birth.
- You're a man who has sex with men, who carries higher exposure risk; vaccination matters as much as testing — see hepatitis a & b vaccines for gay & bisexual men.
- You inject drugs or share equipment, live with someone who has hepatitis B, or are on dialysis.
- You have an autoimmune or liver condition, since some immune-suppressing treatments can reactivate a quiet hepatitis B infection — more on that overlap in autoimmune diseases and hepatitis.
Getting tested: the visit, at-home kits, and cost
Testing is quick and low-drama. In a clinic it's a blood draw with results usually back in a few days. Hepatitis B screening is free or low-cost at health departments, Planned Parenthood, and Title X clinics, and it's often bundled into a broader STI check. You can start the process online and get tested, or compare testing providers to weigh price, turnaround, and whether the hepatitis B panel is included.
A few practical pointers:
- Confirm the order includes the triple panel, not HBsAg alone — the antibody markers tell you whether you're already immune or recovered.
- If you test through an at-home service, hepatitis B requires a true blood sample (a fingerstick or mail-in draw), so read the kit details before ordering.
- Bring your vaccination history if you have it — knowing you completed the hepatitis vaccines series changes how your anti-HBs result is read.
A diagnosis here is common and manageable. Clinics handle hepatitis B daily, and it says nothing about you as a person.
Reading your hepatitis B results
Because three markers are read together, the combination tells the story. Here's how the common patterns translate:
| HBsAg | anti-HBs | total anti-HBc | What it usually means |
|---|---|---|---|
| Negative | Negative | Negative | Susceptible — never infected, not vaccinated. Consider vaccination. |
| Negative | Positive | Negative | Immune from vaccination. |
| Negative | Positive | Positive | Immune from a past, resolved infection. |
| Positive | Negative | Positive | Active infection — acute or chronic. Needs clinical follow-up. |
The 6-month mark defines acute versus chronic: an active infection in the first 6 months after exposure is acute, while HBsAg still positive beyond 6 months is chronic and can be lifelong. Age at infection drives the outcome. Caught in adulthood, hepatitis B becomes chronic in under 5% of people; caught in infancy, it becomes lifelong in about 90%, which is why the birth-dose vaccine matters so much.
If your test is positive
A positive HBsAg isn't a cure-or-nothing situation. Chronic hepatitis B is controlled with daily antivirals such as tenofovir or entecavir that suppress the virus and cut liver-cancer risk, though most people take them long-term CDC treatment. For the full breakdown of medications, monitoring, and what treatment looks like over time, see our dedicated treatment guide, and finish any prescribed course rather than stopping when you feel well.
When to see a clinician
Reach out promptly if any of the following apply:
- You had a recent high-risk exposure — call within days, not weeks, since post-exposure vaccine and immune globulin work best given early.
- You have symptoms of acute hepatitis: yellowing of the eyes or skin (jaundice, which signals the liver is struggling to process bilirubin), dark urine, pale stools, persistent nausea, or right-upper-abdominal pain.
- You're pregnant and haven't been screened this pregnancy — an HBsAg-positive parent's newborn needs both the vaccine and hepatitis B immune globulin within 12 hours of birth to prevent most transmission CDC perinatal.
- Your result is positive, so you can start monitoring and discuss whether antivirals are warranted now or later.