Hepatitis B transmission: how do you catch it?

A hepatitis B infection almost always happens through sex or through blood. The virus is present in blood, semen, pre-ejaculate and vaginal fluid, so unprotected sex is a main route. A reassuring detail: in adults, about 90 to 95 percent clear the virus by themselves.

There are many misunderstandings about how you catch hepatitis B. No, you don't get it from a toilet seat or a glass. Below you'll read calmly which routes do carry risk, how big the chance is, and how to keep an infection unlikely.

How do you get hepatitis B?

You get hepatitis B through blood and through sex. The virus enters your body when infected blood or fluid meets a small wound, a mucous membrane or your bloodstream. That can happen during sex, but also through blood contact another way.

For blood, think of shared needles, but also a razor or toothbrush with traces of blood. During birth the virus can pass from mother to child too. More about the virus in general is in our piece on hepatitis B and C.

According to the RIVM, sex without a condom and blood contact are the main routes. That makes hepatitis B an STI where a condom really makes a difference.

Can you get hepatitis B through sex?

Yes, sex is one of the main routes for hepatitis B. The virus is present in semen, pre-ejaculate and vaginal fluid, so sex without a condom can transmit it. Sex where the penis enters the vagina or anus carries risk in particular.

A condom substantially reduces that risk, because it forms a barrier against those fluids. An infection can never be fully ruled out, but the chance becomes much smaller. With changing partners, getting checked pays off too.

An STI check often includes a conversation about other infections, like HIV. That partly shares the same routes as hepatitis B.

Can you get hepatitis B from a toilet seat or glass?

No, you can't. You don't catch hepatitis B from a toilet seat, sharing a glass or cutlery, or shaking hands. The virus needs blood or certain body fluids that enter your body, and that doesn't happen through ordinary daily contact.

That's an important misunderstanding to clear up. You don't need to be afraid to sit next to someone with hepatitis B or eat together. Hugging, a kiss on the cheek and sharing coffee carry no risk.

The table below lists what is and isn't a transmission route.

How big is the chance of infection?

The chance depends on the route and the situation. With unprotected sex with someone who carries the virus, the chance is real, because hepatitis B is quite infectious through blood and fluid. With a one-off, superficial contact the chance is small.

What often reassures: if you're infected as an adult, your immune system usually clears the virus itself. According to the RIVM, about 90 to 95 percent of adults recover fully on their own. In a smaller share the virus stays.

That doesn't mean you can ignore risk. It mostly means an infection doesn't always lead to lasting problems, certainly not if you know you have it.

How do you prevent hepatitis B?

There's a vaccine against hepatitis B, and that's the strongest form of prevention. In the Netherlands the hepatitis B shot has been part of the national immunisation programme for babies since 2011, so many younger people are already protected. If you're unsure whether you've been vaccinated, your GP can check.

Besides that, a condom substantially reduces the risk during sex. And for blood: don't share needles, razors or toothbrushes. Those are simple habits that make a big difference.

So prevention is partly a shot and partly being smart with blood and sex. You don't have to become tense about it.

When can you get tested after a risk?

After a risk moment there's a wait before a test is reliable. According to Soa Aids Nederland, for hepatitis B you can test about three months after unprotected sex or blood contact. You need that window because the virus takes time to become visible.

You can get checked discreetly and anonymously, without your GP or insurer being involved by default. How such a test works, from prick to result, is in our piece on the hepatitis test.

If you want to test specifically for hepatitis, the hepatitis test gives insight there. Always discuss an unusual result with your GP, who can help you decide whether further steps are needed.

References

• RIVM. Hepatitis B. 2024. rivm.nl
• Soa Aids Nederland. Hepatitis B. 2024. soaaids.nl
• World Health Organization. Hepatitis B fact sheet. 2024. who.int

Every blood test result at Discreet Test includes a professional assessment by a BIG-registered doctor. For treatment decisions, discuss your results with your GP.