Skip to content

3 minute read

How HIV PrEP works

Written by Hi Doctor clinical content teamPublished 3 July 2026

PrEP uses antiretroviral medicine before exposure so HIV has far less chance to establish infection. See what assessment and follow-up involve.

How HIV PrEP works, article cover image
Share:

DIRECT ANSWER

An online consultation lets an EU-licensed doctor review your case and, if appropriate, issue an electronic prescription; each pharmacy decides whether it can dispense it.

Doctor reply in under 2 hours

Average doctor reply under 2 hours; at night and on public holidays it can take longer, always within 24 hours. A prescription only if appropriate.

EU-licensed doctors

Every case is reviewed by an EU-licensed doctor.

Electronic prescription

Each pharmacy decides whether it can dispense an approved prescription; some do not accept PDF prescriptions.

HOW IT WORKS

From consultation to collection

  1. 1

    Consultation

    Answer a secure medical questionnaire online.

  2. 2

    Doctor reviews

    An EU-licensed doctor personally assesses your case.

  3. 3

    Prescription only if appropriate

    The doctor replies in under 2 hours on average and issues a prescription only if it is clinically appropriate.

  4. 4

    Collect at the pharmacy you choose

    Take an approved prescription to the pharmacy you choose; each pharmacy decides whether it can dispense it.

Pre-exposure prophylaxis, or PrEP, is medicine taken by an HIV-negative person to reduce the chance of acquiring HIV. It is one part of combination prevention alongside testing, condoms where wanted, STI care and prompt access to PEP after an emergency exposure.

Blocking early HIV replication

Established oral PrEP combines antiretroviral medicines that block reverse transcriptase, an enzyme HIV needs to copy its genetic material after entering a cell. When enough medicine is present at exposed tissues, the virus is much less able to establish a lasting infection. PrEP does not remove HIV from a person who already has it and is not a complete HIV-treatment regimen.

Adherence creates the protection

Protection depends on following the agreed schedule. Tablets need time and consistent dosing to reach protective levels, and protection does not disappear or appear at the same speed in every tissue. A clinician should explain when you can rely on PrEP and how long to continue after the last possible exposure.

What PrEP does not prevent

PrEP does not prevent gonorrhoea, chlamydia, syphilis, pregnancy or every route of viral hepatitis. Regular STI screening and vaccinations where appropriate remain useful. Condoms are still an option for broader protection, but PrEP can add a strong HIV-specific layer when taken correctly.

When to seek help

PrEP must not be started or restarted without excluding HIV infection at the appropriate time. Fever, rash, sore throat, swollen glands or a flu-like illness after a recent exposure may be signs of acute HIV and need prompt testing. A very recent high-risk exposure may call for urgent post-exposure prophylaxis instead; PEP is time-sensitive and should be assessed immediately.

What to prepare for a medical review

A PrEP review covers recent exposures, the timing and type of HIV tests, kidney function, hepatitis B status, other medicines, pregnancy where relevant, and a wider STI screen. Follow-up testing is essential even when you feel well. Protection depends on taking the agreed schedule correctly, and national access pathways can differ across Europe.

A calm next step

Start with an appropriate HIV test and a clinician-led plan, not tablets from another person. The first prescription should include clear start, missed-dose, follow-up and stopping instructions.

Clinical sources used: European Centre for Disease Prevention and Control PrEP standards and European Medicines Agency product information for emtricitabine/tenofovir disoproxil.

Own your health

Doctor-reviewed guides and new treatments. At most two emails a month.

Written by the Hi Doctor editorial team. General information, not individually reviewed by a doctor.

If the doctor does not approve treatment, we refund the full amount. Every consultation is fully refundable. How refunds work