Medication used before and around potential exposure to prevent HIV acquisition.
Back to the glossarySexual health
PrEP
Pre-exposure prophylaxis: prescription medicine used by HIV-negative people to reduce the chance of acquiring HIV when taken or administered as advised.
Sexual health
In brief
HIV prevention before exposure, supported by testing and follow-up.
PrEP is prevention used before potential HIV exposure. Oral tablets may be taken daily or, for some people and exposure types, on demand; long-acting injectable PrEP is available to selected people through current NHS pathways. A clinic determines suitability, testing, dosing and monitoring.
Emergency medication started after a possible exposure, as soon as possible and no later than the clinical limit.
Antiretroviral medicine for a person living with HIV, protecting health and enabling viral suppression.
A barrier that can reduce HIV, other STI and pregnancy risks depending on use and activity.
Who may benefit
PrEP can benefit people of any gender whose circumstances include relevant HIV exposure. Assessment should consider actual activities and networks rather than stereotypes.
A partner living with HIV who maintains an undetectable viral load does not sexually transmit HIV; clinicians can incorporate U=U into an individual prevention discussion.
Dosing is specific
NHS guidance includes daily oral PrEP and on-demand oral dosing for anal sex in suitable people. On-demand dosing is not recommended for vaginal or frontal sex and may be unsuitable with hepatitis B.
Do not copy a regimen from another person or a glossary. Start, stop and missed-dose advice depends on the activity, medicine and clinical factors.
Testing and monitoring
Before starting, clinics assess HIV status, hepatitis B and kidney function, with ongoing HIV and STI testing and monitoring. Starting PrEP during unrecognised HIV infection can complicate treatment.
PrEP protects against HIV, not other STIs or pregnancy. Other prevention remains available according to personal goals.
Access and choice
PrEP is available through NHS sexual-health services, though delivery pathways vary by nation and local service. England has also begun a selected rollout of long-acting cabotegravir for people unable to use oral PrEP.
Access should be stigma-free and based on informed choice. Taking PrEP is not evidence of promiscuity or infection.
Non-graphic examples
What the umbrella may include
- Taking daily PrEP under clinic guidance.
- Using on-demand PrEP only when clinically suitable for anal sex.
- Completing HIV, hepatitis B and kidney checks before starting.
- Continuing STI testing because PrEP is HIV-specific.
- Discussing injectable PrEP where oral medicine is unsuitable.
Reviewed 30 August 2026
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