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HIV PEP (emergency anti-HIV medicine) (HIV post-exposure prophylaxis (PEP / PEPSE))

An emergency course of anti-HIV medicine that may stop HIV taking hold if it is started very soon after a possible exposure.

✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review

In short

  • PEP is an emergency: start it within 72 hours of possible exposure, and sooner is much better — ideally within 24 hours. Do not delay.
  • It is free on the NHS. In hours, go to a sexual health or HIV clinic; out of hours or at weekends, go to A&E and ask for PEP.
  • You take it every day for 28 days, and you need a follow-up HIV test afterwards to confirm the result.
  • PEP is not guaranteed and is for emergencies only. If you are often at risk, ask a clinic about PrEP, which is taken before sex.

A plain-English summary. The detail — including risks and recovery — is below.

At a glance

TypeEmergency medical treatment (a 28-day course of tablets)
AnaestheticNot needed
How long it takesA short same-day assessment to start; then tablets for 28 days
Hospital stayUsually no hospital stay
Time off workUsually none, though side effects can make you feel off-colour
When you'll see resultsA follow-up HIV test is done after the course; the result is what tells you whether it worked
On the NHS?Free on the NHS from A&E and sexual health clinics for people who meet the guidelines

A general guide. Your specialist will give you advice for your situation.

Best fit

May stop HIV taking hold after a possible exposure, if started in time and taken correctly

Pause if

The exposure was more than 72 hours ago — PEP is no longer effective and a different plan (testing, and PrEP for the future) is needed.

Main recovery point

You start the tablets as soon as possible after being assessed. Side effects like nausea or headache may begin in the first day or two and often settle.

Good aftercare

A clear plan for the full 28-day course and a named contact for side-effect help.

Day of starting

You start the tablets as soon as possible after being assessed. Side effects like nausea or headache may begin in...

First week

Keep taking the tablets daily. If side effects are hard to cope with, contact the clinic rather than stopping —...

Through to day 28

Finish the full course. Missing doses or stopping early reduces the chance it works.

After the course

You will have an HIV test, usually some weeks after finishing, to confirm the result. The clinic will tell you the...

Medical line illustration of hiv prep pep consultation for HIV PEP (emergency anti-HIV medicine).
Illustration only - not a diagnosis, medical advice or a promise of result. Your anatomy and treatment plan may differ. Vuemedics does not publish before-and-after photos.

What is HIV PEP?

PEP (post-exposure prophylaxis) is a course of anti-HIV tablets you take after you may have been exposed to HIV, for example after sex without a condom, a condom breaking, sharing needles, or a needle-stick injury. The idea is to stop HIV taking hold in your body before it can settle in.

PEP is an emergency. It must be started within 72 hours (3 days) of the possible exposure, and the sooner the better — ideally within 24 hours. Every hour matters, so do not wait. The course lasts 28 days and you take it every day.

It is free on the NHS. During clinic hours, go to a sexual health (GUM) clinic or HIV clinic. Outside hours, at weekends or at night, go to an Accident and Emergency (A&E) department and ask for PEP — they can start it. A GP usually cannot start PEP quickly enough.

PEP is not a 'morning after pill' for HIV and is not guaranteed to work. It is for emergencies, not for regular protection. If you are repeatedly at risk, PrEP (a pill taken before sex) is the planned way to protect yourself, and a clinic can arrange it.

Types, options & approaches

There may be different ways to do this. The right approach depends on the clinical question and your circumstances.

PEP after sexual exposure (PEPSE)
The most common reason people are given PEP — after sex without a condom, a condom failure, or sexual assault, where there may have been HIV risk.
PEP after sharing injecting equipment
Considered when needles or other injecting equipment have been shared and there is a possible HIV risk.
Occupational PEP (needle-stick or splash injury)
For healthcare and other workers after a needle-stick or body-fluid exposure at work. Workplaces have a separate route to access this urgently.
PEP after sexual assault
Sexual assault referral centres (SARCs) and sexual health clinics can assess for PEP alongside other care and support, in confidence.

Options at a glance

These are the main approaches described in this guide. The right option depends on the diagnosis, your goals and what your clinician thinks is safe.

PEP after sexual exposure (PEPSE)

The most common reason people are given PEP — after sex without a condom, a condom failure, or sexual assault, where there may have been HIV risk.

PEP after sharing injecting equipment

Considered when needles or other injecting equipment have been shared and there is a possible HIV risk.

Occupational PEP (needle-stick or splash injury)

For healthcare and other workers after a needle-stick or body-fluid exposure at work. Workplaces have a separate route to access this urgently.

PEP after sexual assault

Sexual assault referral centres (SARCs) and sexual health clinics can assess for PEP alongside other care and support, in confidence.

Preparing for your treatment

  • Do not wait to 'prepare' — getting seen quickly is the single most important thing. Go now if you are inside the 72-hour window.
  • If you can, note when the possible exposure happened and roughly what kind of contact it was, as this helps the clinician assess the risk.
  • If you know anything about the other person's HIV status or treatment, mention it — but do not delay seeking help to find out.
  • Bring a list of any regular medicines and any allergies, as a few medicines interact with PEP.
  • Expect an HIV test and other STI tests as part of starting PEP; a baseline test confirms you are HIV-negative before you begin.
  • You do not need anyone's permission and your care is confidential.

What happens

A clinician (in a sexual health clinic, HIV clinic or A&E) will ask about the exposure and your health, then decide whether the risk is high enough that PEP is recommended. PEP is not given for every exposure, because for very low-risk situations the small risks of the medicine may outweigh the benefit.

If PEP is recommended, you will usually have a baseline HIV test and other tests, and be given the tablets to start straight away. You will also be tested for hepatitis B and other STIs, and offered advice and support.

You take the tablets every day for 28 days. You will be given follow-up appointments to check how you are getting on, manage any side effects, and arrange the all-important HIV test after the course finishes.

Is this treatment right for me?

A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.

May not be suitable if…

  • The exposure was more than 72 hours ago — PEP is no longer effective and a different plan (testing, and PrEP for the future) is needed.
  • The risk from the exposure is assessed as very low, where the small risks of the medicine may outweigh any benefit.
  • You are already known to be living with HIV — you need HIV treatment, not PEP.
  • Repeated, ongoing risk where PrEP (taken before sex) is the appropriate planned approach rather than repeated PEP courses.

Delay or rearrange if…

  • Do not delay starting PEP itself — but tell the clinician about pregnancy or breastfeeding, kidney or liver problems, and all your medicines so the right regimen is chosen.
  • If you cannot keep tablets down because of vomiting, the clinic may need to add anti-sickness treatment rather than you stopping.
  • Significant medicine interactions may mean the clinician adjusts the regimen rather than delays it.

Alternatives to discuss

  • PrEP (pre-exposure prophylaxis) for people who are repeatedly at risk — taken before sex, not after.
  • Condoms and not sharing injecting equipment to prevent exposure in the first place.
  • HIV testing alone if the exposure was outside the PEP window, with support and a plan for the future.
  • Treatment as prevention: a partner living with HIV who is on treatment with an undetectable viral load cannot pass it on (U=U).

Before you decide

Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.

What matters most to me?

Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.

What are all my options?

Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.

What would make me pause?

Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.

What happens if I do nothing today?

For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.

Benefits

  • May stop HIV taking hold after a possible exposure, if started in time and taken correctly
  • Free and available urgently on the NHS, including from A&E out of hours
  • Comes with HIV and STI testing and access to ongoing prevention advice
  • Can be a route into PrEP and regular sexual-health support if you are repeatedly at risk
  • Offered confidentially and without judgement, including after sexual assault

Risks & complications

More common
  • Feeling sick, tummy upset or diarrhoea, especially in the first days
  • Headache and tiredness
  • The inconvenience of taking tablets every day for a month and attending follow-up
Less common
  • Side effects troublesome enough that the regimen needs adjusting
  • Interactions with other medicines you take
  • Anxiety while waiting for the follow-up HIV test result
Rare but serious
  • An allergic reaction to the medicine (a rash or flu-like symptoms needs prompt review)
  • Liver or kidney effects, which is why some monitoring is done
  • PEP not working despite being taken correctly — it reduces risk but is not a guarantee

The biggest risk is not the medicine — it is delay. PEP becomes much less likely to work the longer you wait, and useless after 72 hours. If you develop a rash or flu-like illness during or after the course, contact the clinic, as this needs checking. Tell the clinician about all your medicines, as some interact with PEP.

Published figures to discuss

Exact figures for how well PEP works in people are hard to pin down, because it cannot ethically be tested in a placebo trial. The evidence comes from animal studies, observational human studies and biological understanding. What is clear is that PEP reduces risk substantially when started quickly and completed, and that delay and missed doses lower the chance it works. Because of this, we describe the effect in words rather than a single percentage.

FigureReported rangeHow to interpret itSource / confidence
Time limit for starting PEPAs soon as possible, and no later than 72 hoursPEP is an emergency medicine; UK and international guidance advise starting urgently and not starting beyond 72 hours.Guide sourcesClinical context
Treatment course not completed28 daysEffectiveness depends on taking the full course and attending follow-up HIV testing.Guide sourcesClinical context
Side effects affecting adherenceUsually mild but common enough to plan forNausea, diarrhoea, headache or tiredness can occur; modern regimens are usually tolerated but support improves completion.Guide sourcesClinical context
PEP used instead of ongoing preventionSafety-net problemPeople with repeated exposures should be offered PrEP, condoms, vaccination and wider sexual-health support.Guide sourcesClinical context

These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.

What happens afterwards

There is no physical recovery, but you take tablets every day for 28 days and may feel off-colour at first. The part that matters most afterwards is completing the course and having the follow-up HIV test.

Day of starting
You start the tablets as soon as possible after being assessed. Side effects like nausea or headache may begin in the first day or two and often settle.
First week
Keep taking the tablets daily. If side effects are hard to cope with, contact the clinic rather than stopping — they can often help.
Through to day 28
Finish the full course. Missing doses or stopping early reduces the chance it works.
After the course
You will have an HIV test, usually some weeks after finishing, to confirm the result. The clinic will tell you the exact timing.
Ongoing
If you are likely to be at risk again, this is the moment to discuss PrEP and regular testing so you are protected in a planned way.
What's normal — and not a worry
  • Some nausea, tummy upset or headache in the first days that usually eases
  • Tiredness while your body adjusts to the medicine
  • Feeling anxious while you wait for the follow-up test — this is very common
  • No physical change you can feel; the medicine is working quietly in the background

Aftercare

  • Take every dose, ideally at the same time each day, for the full 28 days.
  • Take tablets with food if they upset your stomach, and ask the clinic about anti-sickness help if needed.
  • Do not stop early or skip doses without speaking to the clinic first.
  • Use condoms and avoid sharing injecting equipment while on PEP and afterwards, to avoid further exposure.
  • Keep all follow-up appointments, especially the final HIV test.
  • Tell any other doctor or pharmacist that you are taking PEP, because of medicine interactions.
  • Ask about PrEP if you may be at risk again in future.
Before your treatment
  • The exact date and time of the possible exposure, if you know it
  • A list of your regular medicines and allergies
  • A phone with the clinic's contact details saved
  • A plan for taking tablets at the same time each day for a month
  • Your follow-up test appointment written down
  • Knowing where your nearest sexual health clinic and A&E are

⚠ Get urgent help if…

  • Possible HIV exposure in the last 72 hours — treat this as an emergency and seek PEP now
  • A rash, fever or flu-like illness during or after the course
  • Severe or persistent vomiting or diarrhoea that stops you keeping tablets down
  • Yellowing of the skin or eyes, severe tummy pain, or very dark urine
  • Severe tiredness, breathlessness or feeling generally very unwell
  • Signs of an allergic reaction such as swelling of the face, lips or throat — call 999

Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.

General guidance — it doesn't replace the specific advice your specialist gives you.

Results & realistic expectations

A good result is a negative HIV test at the follow-up point after finishing the course. PEP reduces the risk of HIV but cannot guarantee protection, which is why the follow-up test matters.

A negative test after PEP does not protect you from future exposures. It also does not cover other STIs, so the clinic will check for these separately and may suggest PrEP if you are likely to be at risk again.

How long it lasts

PEP only covers the single exposure it was started for. It gives no ongoing protection. If you are repeatedly at risk of HIV, PrEP (taken before sex) is the planned way to stay protected, and regular sexual-health testing is recommended.

Related tests, treatments or support

Starting PEP is usually combined with testing for other STIs and hepatitis, hepatitis B vaccination if needed, emergency contraception if relevant, and support after sexual assault. It is also a natural point to discuss switching to PrEP for the future.

Follow-up & long-term care

The clinic will arrange follow-up during the course to manage side effects, and an HIV test after it finishes. Further STI testing and a conversation about PrEP and ongoing protection are usually part of this.

Repeat, follow-on and what comes next

  • If side effects are troublesome, the regimen can sometimes be adjusted rather than stopped.
  • A repeat exposure means a fresh assessment — and usually a conversation about moving to PrEP rather than repeated PEP.
  • If the follow-up test is unclear or positive, the clinic will arrange confirmatory testing and, if needed, start HIV treatment promptly.

Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.

What good aftercare looks like

  • A clear plan for the full 28-day course and a named contact for side-effect help.
  • A booked follow-up HIV test with a clear date and a clear way to get the result.
  • Testing for other STIs and hepatitis, with hepatitis B vaccination if needed.
  • A proactive conversation about PrEP and ongoing protection.
  • Confidential, non-judgemental support, including after sexual assault.

What affects the cost

Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:

  • On the NHS, PEP is free for those who meet the guidelines — this should never be a barrier to seeking it urgently.
  • If a private service is used, the consultation fee may apply.
  • The cost of the 28-day course of medicine if obtained privately.
  • Baseline and follow-up HIV and STI testing.
  • Any follow-up appointments to manage side effects and confirm results.
Make sure your written quote includes
  • Confirmation that NHS PEP is free and where to get it urgently (clinic in hours, A&E out of hours)
  • If private: the consultation fee and who you will see
  • If private: the full cost of the 28-day course of medicine
  • Baseline and follow-up HIV/STI testing and how results are given
  • Follow-up appointments included
  • What happens, and who to contact, if you have side effects or the result is unclear

On the NHS? PEP is free on the NHS from sexual health clinics and A&E for people who meet the guidelines; private services exist but speed and free urgent access make the NHS route the priority here.

You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.

Choosing a specialist safely

  • Check the specialist is on the GMC Specialist Register for this area.
  • Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
  • You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
  • Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
  • You're entitled to your total cost in writing — including any follow-up — before you decide.

How Vuemedics verifies every consultant →

Questions to ask your medical professional

Take this to your consultation. A good specialist will welcome every one of these.

  • Based on what happened, is my risk high enough that PEP is recommended for me?
  • When exactly should I have my follow-up HIV test, and how will I get the result?
  • Could any of my regular medicines interact with PEP?
  • What should I do if I am sick shortly after taking a dose or miss a dose?
  • Am I someone who should be considering PrEP for the future?
  • What other tests or vaccinations should I have alongside PEP?
  • Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
  • Will you be the specialist who carries out my treatment, and who looks after me afterwards?
  • What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
  • What does a realistic result look like — and what can this treatment not achieve?
  • What are my options, including waiting, doing nothing for now, or choosing a different approach?
  • Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
  • What is the total cost in writing, including any follow-ups, and how much time do I have to decide?

Frequently asked questions

How quickly do I need to start PEP?
As soon as possible, and definitely within 72 hours (3 days) of the exposure. Ideally within 24 hours. After 72 hours it is no longer effective, so do not wait — go to a clinic or A&E now.
Where can I get PEP?
Free on the NHS. During opening hours, go to a sexual health (GUM) or HIV clinic. Out of hours, at weekends or at night, go to an Accident and Emergency (A&E) department and ask for PEP. A GP usually cannot start it fast enough.
Is PEP guaranteed to work?
No. PEP reduces the risk of HIV but cannot guarantee it. It works best when started quickly and taken every day for the full 28 days. A follow-up HIV test confirms the result.
What are the side effects?
Many people get some nausea, tummy upset, headache or tiredness, especially early on, which usually settles. If side effects are hard to manage, contact the clinic rather than stopping the course.
Does PEP protect against other STIs or pregnancy?
No. PEP only targets HIV. The clinic will test for other STIs and can offer emergency contraception, hepatitis B protection and support if relevant.
What if I keep being at risk of HIV?
Repeated courses of PEP are not the right approach. If you are often at risk, ask the clinic about PrEP — a pill taken before sex that is highly effective at preventing HIV when taken correctly.
Is it confidential?
Yes. Sexual health care in the UK is confidential. You can be seen without involving your GP, and support is available without judgement, including after sexual assault.

Find a verified specialist for hiv pep (emergency anti-hiv medicine)

Every consultant is GMC-checked and independently reviewed. Search by postcode and distance, or switch to a map. Ordered by rating, relevance and recency — never by who pays.

How we made this page

Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →

Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.

Sources & standards: NHS — HIV and AIDS (treatment, including PEP) Terrence Higgins Trust — PEP BASHH — PEP: the basics (patient leaflet) Guy's and St Thomas' NHS — PEP emergency medicines for exposure to HIV NHS Scotland Right Decisions — PEPSE protocol

Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.

Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.

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