Post-exposure Post-exposure prophylaxis (PEP) for HIV
If you think you may have been exposed to HIV, PEP may reduce your chance of acquiring HIV.
PEP stands for post-exposure prophylaxis. It is a course of HIV medicines taken by someone who does not have HIV after a possible exposure.
PEP is most effective when started as soon as possible after exposure. It should be started within 72 hours of the exposure. The sooner you start PEP, the more effective it is.
PEP is normally taken for 28 days.
Think you may have been exposed to HIV within the last 72 hours?
PEP may reduce your chance of acquiring HIV. Contact a sexual health service as soon as possible. PEP is most effective when started early.
If you think you may need PEP
Do not wait to see if you develop symptoms or wait for an HIV test.
If you think you may have been exposed to HIV within the last 72 hours, contact a sexual health service as soon as possible for advice.
PEP is available from sexual health services and, outside normal opening hours, from A&E departments in Scotland.
You can also read our PEP information leaflet.
PEP after sexual exposure
HIV can be transmitted through some types of sexual contact when one person has HIV and the virus is detectable.
If you have had sex without a condom or another form of HIV prevention and think you may have been exposed to HIV, PEP may be appropriate.
Whether PEP is recommended depends on factors including:
- The type of sexual contact
- Whether the other person has HIV
- Whether the person with HIV is taking effective treatment
- Their viral load, if known
- When the exposure happened
- Whether you or the other person are taking HIV prevention medication
A healthcare professional will assess your individual circumstances and advise whether PEP is appropriate.
What if the other person has HIV?
If a person living with HIV is taking effective treatment and has an undetectable viral load, they cannot pass HIV on through sex. This is known as U=U (Undetectable = Untransmittable).
You can find more information about U=U from i-Base.
If you do not know whether someone has HIV or what their viral load is, you can still seek urgent advice. A healthcare professional can assess whether PEP is appropriate.
PEP after blood exposure
HIV can also be transmitted through contact with infected blood.
Examples of possible exposure include:
- Sharing needles or injecting equipment with someone who has HIV
- An accidental needlestick injury involving equipment that may have been contaminated with HIV-infected blood
- Other situations where blood may enter your bloodstream
If you think you have been exposed to HIV through blood, seek medical advice as soon as possible.
A healthcare professional will assess the exposure and advise whether PEP is appropriate.
If you do not know the HIV status of the person involved, you should still seek advice. Do not delay seeking help while trying to find out their HIV status.
When should I take PEP?
PEP needs to be started as soon as possible after exposure.
- PEP is most effective when started as soon as possible.
- It can be started up to 72 hours after exposure.
- PEP is not recommended to be started more than 72 hours after exposure.
- The usual course of PEP lasts 28 days.
If you think you may have been exposed to HIV within the last 72 hours, seek urgent advice now.
What happens when I ask about PEP?
A healthcare professional will ask you about the exposure and assess your individual risk.
They may ask about:
- When the exposure happened
- What type of exposure occurred
- Whether the exposure was sexual or involved blood
- Whether the other person is known to have HIV
- Whether the person with HIV is taking treatment and has an undetectable viral load, if known
- Any HIV prevention medication you or the other person may be taking
They will then advise you whether PEP is appropriate.