Post-Exposure Prophylaxis ( PEP ) Guidelines - Community Exposure to Possible HIV

Publication: 01/10/2010  
Next review: 14/10/2025  
Clinical Guideline
ID: 2274 
Approved By: Trust Clinical Guidelines Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2022  


This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Community exposure to possible HIV
Post exposure prophylaxis (PEP) guidelines


Following sexual or percutaneous exposure to HIV it may take up to 48-72 hrs before HIV can be detected in lymph nodes and up to 5 days before it can be detected in the blood. Therefore, there is a window of opportunity for preventing established HIV infection after sexual exposure or sharing IV equipment by using PEP. PEP is best given early, preferably within 2 hours of the exposure, so the decision whether to initiate PEP is an urgent one, and first doses should not be delayed once a need is identified.

This local guideline seeks to ensure that PEP is provided in Leeds Teaching Hospitals Trust in line with the British Society of Sexual Health and HIV (BASHH) national guidelines (2021) and Department of Health advice.

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Provision of PEP

During clinic hours, anyone requesting PEP from sexual exposure should be referred directly to Leeds Sexual Health where they will be seen in the Merrion Centre site (balcony level). Up to date information on clinic closures and Covid working changes is available online  Health Care Professionals can speak to a clinician via the professional line in office hours (0113 3920328) or Health Advisors (0113 3920325). Outside of these hours the Emergency Departments in Leeds will provide PEP, and specialist advice can be obtained from the GU/ID registrar on call via switch.

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Evidence for the use of PEP

The use of PEP is now widespread and there is evidence from animal studies and observational data that it is effective in preventing sexually acquired HIV infection. Studies have shown the best efficacy when given within 24hrs, with possible benefit up to 72 hrs after exposure. Study recommended duration of PEP is 28 days.

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Assessing the need for PEP

  • The decision to initiate PEP should be made on a case by case basis on the balance of risk versus benefit using the included flowchart.
  • Initiation beyond 72 hours after exposure is not recommended.
  • Where the exposure is classed as ‘consider’, PEP should be prescribed if there are additional risk factors that may increase the likelihood of transmission e.g. sexual assault, trauma from sex, group sex, presence of an STI or genital ulcer disease, or the donor is thought to have acute or untreated HIV infection. If in any doubt, we would recommend starting PEP.
  • Where the exposure is classed as ‘generally not recommended’, the potential toxicity and inconvenience of PEP is likely to outweigh the benefits as the calculated risk of transmission is very low. PEP would rarely be given unless there were clear additional factors increasing the likelihood of transmission eg sexual assault, trauma from sex, group sex, presence of an STI or genital ulcer disease, or the donor is thought to have acute or untreated HIV infection.
  • For human bites, PEP is ‘generally not recommended’ (unless known HIV donor not on treatment, visible blood in saliva, and severe/deep injury
  • For community needlestick injuries from a discarded needle, PEP is not recommended, (unless the needle is freshly discarded or contains visible non-dried blood.)

Undetectable = untransmittable

For people living with HIV who have an undetectable HIV viral load and are stable on treatment, there is effectively no risk of sexual transmission, supported by strong RCT evidence. Cohort studies have recorded no sexual transmissions from over 10000 exposures. PEP is not required in these circumstances. However, if there is any doubt over the source’s viral load or treatment history then PEP should be started whilst confirmation is sought.

Contact the oncall GU/ID registrar via switch for further discussion if required

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Baseline investigations:

The tests below are indicated. PEP should not be started without taking a baseline HIV test but do not wait for results before starting. If the baseline HIV test is positive, or there is markedly abnormal kidney or liver function, please contact GU/ID registrar oncall for advice.



HIV serology

HIV serology (Ag/Ab)

Other tests:

eGFR, creatinine, ALT


HepBsAg (if not known to be vaccinated with documented AntiHBs>10)

Hepatitis C ab

Pregnancy test (if indicated)

 Standard Prescribing PEP:

The recommended duration of PEP is 28 days.

PEP is now provided in a standard ‘pack’ containing a 30 day supply of:

  • Emtricitabine 200/Tenofovir DF 245 one tablet po once daily
  • Raltegravir 600mg tablets po, take 2 once daily (1200mg od)

Caution in Pregnancy:

There is no evidence to support the above regime in pregnancy. In the event of a pregnant female requiring PEP the following should be obtained, from either the outpatient pharmacy within hours, or from the oncall pharmacist out of hours:

28 day hospital prescription for

  • Emtricitabine 200/Tenofovir DF 245 one tablet po once daily
  • Raltegravir 400mg bd (12 hours apart)

This regime is kept in stock in both LGI and SJUH outpatient pharmacies. Opening hours as below


Monday - Friday

Saturday & Sunday

Bank holidays

Chancellor Wing LGI

09:00 - 20:00

09:00 - 16:00

10:00 - 16:00


09:00 - 21:00

09:00 - 17:00

10:00 - 17:00

All patients commenced on PEP should be advised to attend Leeds Sexual Health for follow-up. The PEP proforma should be completed for all patients requesting PEP and emailed to Leeds Sexual Health (

See patient information leaflet for contact details for

Emtricitabine 200/Tenofovir DF 245 is a tablet containing a combination of two Nucleoside Reverse Transcriptase Inhibitors (NRTIs) tenofovir and emtricitabine. It may cause mild nausea and vomiting but routine antiemetics are not necessary. It can also be associated with renal impairment although these effects are more commonly associated with long term use.

Raltegravir is an integrase inhibitor. It is well tolerated with minimal side effects. Both 600mg tablets should be taken together, at the same time as the emtricitabine/tenofovir. Myopathy and rhabdomyolysis have been reported rarely; caution is advised in individuals with a history of these conditions.

Drug interactions are possible with emtricitabine/tenofovir and raltegravir. Calcium, magnesium and iron containing drugs can affect the absorption of raltegravir so should not be co-administered with it but taken separately a few hours later. A full drug history should be taken including herbal/over the counter medications. Interactions can be checked on or with medicines information on 0113 3965377, or the pharmacist or GUM/ID Specialist Trainee on-call.

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I) Pregnancy

Being pregnant is not a contraindication to prescribing PEP but pregnant women will need further discussion about the medication. All women should be assessed regarding their risk of pregnancy and should be discussed with the GUM/ID Specialist Trainee on-call if confirmed pregnant. Raltegravir should always be dosed as 400mg twice daily in pregnancy. This will need to be sourced via the outpatient pharmacy or via the oncall pharmacist.

II) Hepatitis B

Consider hepatitis B post exposure prevention by vaccinating if no documented evidence of AnitHBs >10. 

III) Contraception

Emergency contraception:  If suitable for emergency contraception they should be given levonorgestrel 1.5mg if within 72 hours of last unprotected sex (3mg advised if weigh >70kg) or ellaOne® (ulipristal acetate 30mg) can be used up to 5 days after unprotected sex. There are no drug drug interactions with this PEP regime. 

Ongoing contraception: There are no interactions with hormonal contraceptives (pills, patches or implants), however women taking PEP should be advised to use condoms during the duration of PEP and until they have had their final HIV test result.

IV) In patients with ≥CKD Grade 3 renal impairment Tenofovir DF should not be used. An alternative regimen should be discussed with the GUM/ID Specialist Trainee on-call. During opening hours, a prescription can be taken to outpatient pharmacy. If out of hours the on-call pharmacist will need to be contacted.

V) Return from abroad with a PEP regime different from UK prescription: Patients can sometimes present requesting review or further prescription of PEP after being commenced abroad. If the regime is different from that normally prescribed in the UK, contact the GUM/ID Specialist Trainee on-call for advice or direct to Leeds Sexual health in opening hours.

VI) Information about ‘donor’ / source patient: if the source patient is confirmed HIV positive and there is evidence that they may have failed treatment in the past or have a resistant strain of virus then it may be necessary to alter the drugs from the standard PEP regimen. However DO NOT DELAY COMMENCING PEP. Consider administering initial doses of standard PEP whilst further information / expertise is being sought. The regimen may be modified in the light of emerging information at early review by Leeds Sexual Health.

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  • There is no guarantee that PEP will prevent seroconversion to HIV, and PEP should not be considered to be an alternative to safer sex practices. All patients who present requesting PEP should be referred to Leeds Sexual Health for information about future alternatives available including PrEP.
  • PEP can interact with other drugs including recreational drugs or herbal remedies. Patients taking calcium, magnesium or iron containing drugs (such as mineral supplements or within antacids), can have reduced absorption of raltegravir, therefore these drugs must be dosed apart from the raltegravir.
  • PEP can cause some side effects including nausea, vomiting, headaches and rash which are usually mild but if problematic, the patient should be advised to either attend Leeds Sexual Health during clinic opening hours or if out of hours to contact the GUM/ID Specialist Trainee on-call via the LTHT switchboard
  • PEP should not be given to anyone already living with HIV due to the potential to cause resistance and future treatment difficulties. For this reason a baseline HIV test is clinically necessary.
  • PEP may occasionally cause problems such as abnormalities in liver/kidney function. For this reason blood tests are taken before starting PEP to look for any potential complications associated with the treatment.
  • PEP is a 28 day course of mediation. The packs contain 30 days, leaving 2 days spare. The patient can use these in case of lost pills, or discard once they have completed 28 days.
  • Anyone considered for / commenced on PEP after a high-risk sexual exposure should be advised to avoid having unprotected sex or donating blood until they have had a negative HIV test at 8 weeks after completing PEP. Women should be advised to avoid conception during the same time period.
  • Take the PEP at the same time each day as per the instructions on the packet:

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The PEP proforma should be completed for all patients requesting PEP and emailed to Leeds Sexual Health (

Inform patients that they need to attend Leeds Sexual Health for follow-up, and they should be directed to the website for up to date opening times and access advice. Leeds Sexual Health can be contacted for professional advice 0900-1700 weekdays (0113 3920328 or 0113 3920325). The GUM/ID Specialist Trainee on-call can be contacted via switchboard for advice between 1700 and 0900.

All patients should be given the LSH PEP information leaflet.

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Record: 2274
Clinical condition:

HIV infection

Target patient group:
Target professional group(s): Secondary Care Doctors
Secondary Care Nurses
Adapted from:

Evidence base

Not supplied

Approved By

Trust Clinical Guidelines Group

Document history

LHP version 2.0

Related information

Not supplied

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