Key takeaways
- CDC recommends hepatitis B screening at least once for all adults 18 and older, using a three-test panel: HBsAg, anti-HBs, and total anti-HBc.
- CDC recommends hepatitis C screening at least once for all adults 18 and older, and during each pregnancy.
- Hepatitis C testing is a two-step process: an antibody test first, then an HCV RNA test if the antibody is reactive.
- A reactive hepatitis C antibody with no detectable RNA usually means no current infection.
- After a recent possible exposure, antibody tests can be negative for weeks. Ask about RNA testing and retesting.
Hepatitis B and hepatitis C are different viruses, and each has its own set of blood tests. That's why lab reports can list several hepatitis results with very different meanings. One marker might mean you're protected by a vaccine, another might mean you had an infection years ago, and another might mean you need care now.
This guide explains what each test is checking for, who CDC says should be screened, and how to read the results you're most likely to see.
Who should be screened
Hepatitis B
In 2023 CDC broadened its guidance. It now recommends that all adults 18 and older be screened at least once using a three-test panel, and that anyone who asks for hepatitis B testing get it, whether or not they share a risk factor (CDC hepatitis B testing guidance). People with ongoing risk, such as those with certain exposures or a partner with hepatitis B, may need periodic testing beyond that one-time screen.
Hepatitis C
CDC recommends hepatitis C screening at least once in a lifetime for all adults 18 and older, and during each pregnancy, except in settings where very few people test positive (CDC hepatitis C testing guidance). People with ongoing risk, such as current injection drug use, need repeat testing.
Is hepatitis an STI?
Hepatitis B spreads easily through sex as well as through blood. Hepatitis C spreads mainly through blood, though sexual transmission does happen, particularly with sex that may involve blood exposure and among people with HIV. That's why hepatitis tests appear on some STI panels and not others. Check the test list before you order.
Hepatitis B: the three-test panel
Each hepatitis B marker answers its own question:
| Test | What it detects | The question it answers |
|---|---|---|
| HBsAg (surface antigen) | A protein from the virus itself | Is there hepatitis B infection right now? |
| Anti-HBs (surface antibody) | Antibody that protects against hepatitis B | Am I immune, from vaccination or a past infection? |
| Total anti-HBc (core antibody) | Antibody that only infection produces, not the vaccine | Have I ever been infected? |
| IgM anti-HBc | An early-stage core antibody | Was the infection recent (roughly the last 6 months)? |
Common hepatitis B result patterns
Based on CDC's interpretation guidance:
- All three negative: No infection and no immunity. You're susceptible, so ask about vaccination.
- Only anti-HBs positive: Immune from vaccination, if you have a documented vaccine series. If you don't, CDC suggests completing the series.
- Anti-HBs and anti-HBc positive, HBsAg negative: A past infection that has resolved. You're not infectious, but there is a small risk of the virus reactivating, for example during certain immune-suppressing treatments. Tell future clinicians about this result.
- HBsAg and anti-HBc positive: Current infection, either acute or chronic. You need to be linked to care. IgM anti-HBc helps tell a recent infection from a long-standing one.
- Only anti-HBc positive: This "isolated core antibody" result has several possible explanations, including a false positive. It needs clinical follow-up.
One more detail: CDC notes that HBsAg can be briefly positive in the 30 days after a hepatitis B vaccine dose. If you were vaccinated recently, mention it.
Hepatitis C: antibody first, then RNA
Hepatitis C testing follows two steps:
- HCV antibody test. Shows whether you've ever been infected.
- HCV RNA test. Run when the antibody test is reactive, to see whether the virus is in your blood now. CDC notes that labs often run this automatically on the same sample.
| Antibody | RNA | Usual meaning |
|---|---|---|
| Non-reactive | Not run | No hepatitis C antibody detected. If the exposure was recent, ask whether you need RNA testing or a repeat test. |
| Reactive | Detected | Current hepatitis C infection. Get linked to care. Current treatment cures most people. |
| Reactive | Not detected | No current infection. Usually a past infection that cleared or was cured, or occasionally a false-positive antibody. |
The antibody usually stays positive for life, even after a cure. That's why someone treated years ago can still have a reactive antibody result. The RNA result tells you whether there's an infection now.
Timing after a possible exposure
A screening test reflects your past exposures. A test after a specific exposure is a timing question.
- Hepatitis C: CDC says antibodies can take 8–11 weeks to appear. If you might have been exposed in the past 6 months, CDC recommends HCV RNA testing whatever the antibody result.
- Hepatitis B: HBsAg takes weeks to become detectable after infection. If the exposure was recent and your first test is negative, ask a clinician when to repeat it. Our window periods guide covers common ranges.
- Not vaccinated against hepatitis B? After a known exposure, preventive treatment may be an option, and it's time-sensitive. Contact a clinician promptly rather than waiting to test.
Seek care promptly if you have symptoms
Yellowing of the skin or eyes, dark urine, pale stools, significant abdominal pain, or unusual fatigue after a possible exposure should be evaluated in person, not only with a mail-in test.
Where to get tested
Hepatitis B and C screening is often part of routine primary care and prenatal care, but it isn't automatic. Ask for it by name, and confirm which markers were ordered. Health departments and community health centers often offer it at low or no cost; see free STD testing options.
Some online lab-order services include hepatitis B and C on their menus. If you go that route, make sure the hepatitis B test is the marker you need (HBsAg alone doesn't show immunity), and that a reactive hepatitis C antibody leads to RNA testing or a clear referral.
Prefer to order a lab test online?
Lab-based testing through STDcheck
STDcheck lets you order tests online and give a sample at a nearby partner lab, with no appointment needed. Check its current menu for the specific hepatitis B and C tests you want, and plan to follow up with a clinician on any reactive result.
Visit STDcheck.com →What to do with your results
- Susceptible to hepatitis B (all markers negative): Ask about the hepatitis B vaccine.
- Current hepatitis B (HBsAg positive): See a clinician for further testing and monitoring. Household members and sex partners should be tested and vaccinated if they're susceptible.
- Current hepatitis C (RNA detected): Ask about treatment. Most people can be cured.
- Resolved infection: Keep a copy of the result. It matters if you later need treatment that suppresses the immune system.
For general next steps after any positive result, see what happens after a positive at-home STI test.
Frequently asked questions
Which hepatitis B test shows if I'm vaccinated?
Anti-HBs, the surface antibody. A positive anti-HBs with negative HBsAg and negative core antibody usually means immunity from vaccination.
Does a positive hepatitis C antibody mean I have hepatitis C?
Not necessarily. It means you've been exposed at some point. An HCV RNA test shows whether there's a current infection. A reactive antibody with undetectable RNA usually means no current infection.
How long after exposure should I test for hepatitis C?
Antibodies can take 8–11 weeks to appear. CDC recommends HCV RNA testing for people who may have been exposed within the past 6 months, regardless of the antibody result.
Do I need hepatitis screening if I feel fine?
CDC recommends one-time hepatitis B and hepatitis C screening for all adults 18 and older, because both infections can be silent for years.
Is hepatitis included in a standard STI panel?
Sometimes. Some panels include hepatitis B and C, others don't, and some include only one hepatitis B marker. Read the test list before ordering.
Sources
- CDC: Hepatitis B screening and testing
- CDC: Clinical screening and diagnosis for hepatitis C
- CDC STI Treatment Guidelines: Screening recommendations
Guidance changes. When timing or treatment matters, check the current linked guidance or ask a clinician.
Disclaimer: This article is for informational purposes only and does not diagnose, prescribe, or replace individualized medical care. Testing and treatment decisions should be made with a qualified healthcare provider. Some links on this page are affiliate links; we may earn a commission at no extra cost to you.