HIV: testing, PrEP and PEP

After a possible HIV exposure, contact a sexual health clinic or A&E now in the UK, or an emergency department or urgent care provider in the US and elsewhere. Ask about PEP. It must begin within 72 hours, and the sooner it begins, the better.

PEP means post-exposure prophylaxis: medicine used after a possible exposure. Do not wait for symptoms or a home-test result before seeking this assessment. If more than 72 hours have passed, still contact a sexual health clinic or doctor for testing advice.

Testing does not depend on how you feel

HIV is a virus that attacks the immune system. Symptoms alone cannot tell you whether you have HIV. Testing is the way to know your HIV status. There is currently no cure, but treatment allows most people with HIV to live a long, healthy life.

Tests usually use blood or oral fluid. No HIV test can detect infection immediately after exposure. The clinic will take the window period into account when advising you when to test and whether you need follow-up. Home antibody tests that flag a possible infection need confirmatory testing through a healthcare service.

HIV is not spread through ordinary contact such as hugging, kissing, sharing food or shaking hands. Those everyday interactions do not require HIV prevention medicine.

What undetectable equals untransmittable means

HIV treatment can reduce the amount of virus in the blood to an undetectable level. People taking treatment who maintain that level do not transmit HIV through sex. This is called undetectable equals untransmittable, or U=U.

The HIV team checks viral load with blood tests. U=U describes sexual transmission; it is not a reason to share injecting equipment. CDC says an undetectable viral load probably reduces transmission through shared equipment, but the size of that reduction is unknown.

PrEP is prevention before exposure

PrEP means pre-exposure prophylaxis. It is medicine for people without HIV who may be exposed through sex or injecting drug use. Options include pills and injections. PrEP reduces HIV risk, but it does not prevent pregnancy or other STIs.

An HIV test is needed before PrEP is prescribed, and follow-up visits and testing continue during care. Follow your clinician’s instructions about using it and when protection can be relied on. Do not stop prescribed PrEP without talking to your doctor.

Tell the clinician if you are trying to conceive, pregnant or breastfeeding. CDC says PrEP can help prevent HIV in these situations and recommends discussing whether it is suitable with your healthcare provider.

Access and advice differ between countries

In the UK, PrEP is available free from NHS sexual health clinics. In the US, CDC says most insurance plans and state Medicaid programmes cover PrEP. Ask the service to check the cost of the medicine, appointments and laboratory tests separately. Assistance programmes may cover different parts of care.

WHO recommends several prevention options: oral PrEP, a dapivirine vaginal ring, and long-acting injections of cabotegravir or lenacapavir. Ask a local clinician which options they can provide and which are suitable for you.

Advice on on-demand PrEP also differs. NHS information describes it as an option for some people, while CDC does not recommend it. Ask your prescribing clinic for a plan that suits you. Do not use another person’s schedule.

Getting help after an exposure

A possible exposure within 72 hours needs immediate assessment for PEP through the services above. For an older exposure, arrange testing with a sexual health clinic or doctor. If exposure may happen repeatedly, ask about PrEP and a longer-term prevention plan.

Before leaving, ask who to contact with medicine questions and when to return. Write down the plan, including any follow-up appointments, in the clinician’s words so you can refer to it later.