New UK guidelines published on PEP after sexual exposure (March 2006)
The British Association for Sexual Health and HIV (BASHH) published new guidelines for post-exposure prophylaxis after sexual exposure (PEPSE) to HIV in the February issue of the International Journal of STD and AIDS. 
The document includes a review of the current data to support the use of PEPSE, considers how to calculate the risks of HIV infection after a potential exposure, and provides recommendations on when PEPSE would and would not be considered.
Other areas included are the possible impact on sexual behaviour, cost-effectiveness, and issues relating to service provision. Throughout the document, consideration is given to the place of PEPSE within the broader context of HIV prevention strategies and sexual health.
Guidelines available to download free as a PDF file from the BASHH website:
These guidelines are welcomed as they provide a medical basis for broadening access to PEP following sexual exposure. Some health campaigns have focused on PEPSE, which is therefore available in some hospitals.  However, information about which clinics provide PEPSE, is not widely publicised.
As with occupational exposure, the earlier PEP is started, the greater the chance it will be effective. For occupational exposure this is recommended within 2 hours, and not later than 72 hours. BASHH guidelines recommend that service provision in the NHS should aim to provide a service within 24 hours, but that an audited outcome could be 90% provision of PEPSE within 72 hours.
Although access to a doctor with experience of HIV is recommended, especially for HIV testing, the guidelines emphasise that this should not be a barrier to accessing PEP.
Wider availability of starter packs that contain 3-5 days initial treatment, similar to those used for occupational exposure, is suggested, and these were used in some of the key studies referenced in the guidelines. 
The guidelines do not address the use of initial dose of PEPSE being provided by the HIV-positive partner (for example in the case of a condom breakage), which in the absence of easy access or starter packs can provide immediate antiviral activity while negotiating any A&E department or HIV clinic. This is already practised by sero-different partners who are aware of the potential benefit of PEPSE and are aware of these issues, though nevirapine is no longer recommended for PEP due to liver toxicity in people with high CD4 counts, and exposure to single doses of efavirenz-based regimen that was not followed by full PEP would risk resistance if the person was already HIV-positive or later seroconverted.
Cost-effectiveness is addressed in the guidelines. However, the limited provision of PEPSE so far, is clearly related to short-term costs rather than long-term savings.
- Fisher M, Benn P, Evans B et al. UK Guideline for the use of post-exposure prophylaxis for HIV following sexual exposure. International Journal of STD and AIDS, 2006; 17: 81-92.
- CHAPS/THT online campaign for gay men includes information and a list of clinics providing PEP (after having completed a brief online risk assessment.