PrEP for HIV and hepatitis B: what is the connection?

Why PrEP and hepatitis B are connected

PrEP is pre-exposure prophylaxis against HIV. Oral PrEP commonly combines tenofovir (TDF or TAF) with emtricitabine, and tenofovir is also a first-line treatment for chronic hepatitis B. So a medicine taken to prevent HIV also acts on hepatitis B virus in the body.

That is why hepatitis B testing usually comes before starting PrEP: the result changes both the regimen and the follow-up plan.

Oral PrEP also suppresses hepatitis B

If you have chronic hepatitis B and take tenofovir-containing oral PrEP, HBV DNA is often suppressed and liver tests may improve. That incidental treatment looks helpful, but it creates a problem: hepatitis B control is hidden behind the PrEP prescription.

If oral PrEP is later stopped, for a regimen change, a break, or a switch to a prevention method without tenofovir, the suppressed hepatitis B virus can become active again.

Long-acting injectable PrEP does not treat hepatitis B

Long-acting injectable PrEP, such as cabotegravir, has a different target from tenofovir and does not suppress hepatitis B virus. Using it for HIV prevention does not treat hepatitis B, and stopping it does not cause a hepatitis B flare through withdrawal of an antiviral.

It also does not prevent hepatitis B. Whatever PrEP you use, hepatitis B prevention still depends on vaccination, condoms, and avoiding blood exposure.

Stopping oral PrEP can cause a hepatitis B flare

For people with hepatitis B, stopping a tenofovir-containing medicine needs a plan, not a casual decision. Rebound can show up as rising HBV DNA and ALT, sometimes with a hepatitis flare, and the risk is higher with cirrhosis.

So if you take oral PrEP and have hepatitis B, any decision to stop, switch, or move to injectable PrEP should be discussed with a clinician in advance, with HBV DNA and liver tests arranged afterwards.

What to test before starting PrEP

Testing usually includes HIV, kidney function, hepatitis B serology (HBsAg, anti-HBs, anti-HBc), and when indicated HBV DNA, hepatitis C, and sexually transmitted infections. Guidance varies by region, but hepatitis B screening is one of the key steps.

If HBsAg is positive, the clinician needs to determine the infection status and discuss whether the PrEP regimen will also serve as hepatitis B treatment and how to monitor after stopping. If all hepatitis B markers are negative, hepatitis B vaccination is recommended first.

If you already have hepatitis B

Discuss three paths with a clinician: continue tenofovir-containing oral PrEP as part of hepatitis B treatment; switch to a prevention method that does not act on hepatitis B while prescribing a separate hepatitis B antiviral; or stop PrEP with hepatitis B monitoring and follow-up treatment arranged first.

Do not stop oral PrEP on your own to see whether the virus rebounds, and do not use PrEP as a hepatitis B vaccine. If HIV is also present, the whole plan should be coordinated by an HIV clinician.

Questions to ask at your visit

1. Does my PrEP regimen contain tenofovir, and will it affect hepatitis B?
2. Was I tested for HBsAg, anti-HBs, and anti-HBc before starting PrEP?
3. If I have hepatitis B, how should HBV DNA and ALT be checked after stopping PrEP?
4. If I switch to injectable PrEP, what happens to my hepatitis B treatment?
5. Do I need hepatitis B vaccination?
6. If fatigue, jaundice, or dark urine appear, whom should I contact?

Action checklist

Confirm hepatitis B screening before starting PrEP. Do not stop oral PrEP or switch to injectable PrEP on your own. If you stop tenofovir-containing PrEP, arrange HBV DNA and liver tests in advance. Vaccination, condoms, and avoiding blood exposure remain the core of hepatitis B prevention. Seek care promptly for jaundice, dark urine, marked fatigue, or abdominal swelling.