Post-Exposure Prophylaxis Guidelines for Homosexual Males in Canada
For a homosexual male in Canada with potential HIV exposure, initiate a 28-day course of three-drug antiretroviral therapy (preferably bictegravir/emtricitabine/tenofovir alafenamide as a single-tablet regimen) as soon as possible within 72 hours of exposure, ideally within 24 hours. 1
Timing is Critical
- Start PEP immediately—do not delay for HIV test results or source person assessment. 2
- PEP must be initiated within 72 hours of exposure to be effective, with efficacy declining significantly after 24 hours 1
- After 72 hours, PEP is not recommended as the diminished benefit does not outweigh the risks 2
Risk Assessment for MSM Exposures
Receptive anal intercourse represents the highest per-act transmission risk among sexual exposures, followed by insertive anal intercourse 2
Key factors that increase transmission risk include:
- Known HIV-positive source partner 2
- Source partner with high viral load or recent infection 2
- Presence of mucosal trauma or bleeding 2
- Condomless intercourse 2
Baseline Evaluation
Perform rapid HIV antibody or antigen-antibody testing immediately, but do not wait for results before starting PEP 2, 1
Additional baseline testing should include:
- Hepatitis B and C screening 2
- Testing for other sexually transmitted infections (gonorrhea, chlamydia, syphilis) at genital and non-genital sites 2
- Serum creatinine to assess renal function 1
Preferred PEP Regimens
The first-line regimen is bictegravir/emtricitabine/tenofovir alafenamide (single-tablet, once-daily) 1
Alternative regimen:
- Dolutegravir plus (tenofovir alafenamide or tenofovir disoproxil fumarate) plus (emtricitabine or lamivudine) 1
Provide the full 28-day prescription at the initial visit to improve completion rates 1
Source Person Assessment
If the source person's HIV status is known:
- If HIV-positive: Proceed with PEP 2
- If HIV-negative (confirmed with fourth-generation antigen-antibody test): PEP not indicated 2
If source person status is unknown:
- For MSM populations (high HIV prevalence group), the risk may be substantial—initiate PEP while attempting to determine source status 2
- PEP can be discontinued if source is later confirmed HIV-negative 2
Follow-Up Testing Schedule
HIV testing at 4-6 weeks and 3 months post-exposure 2
Additional monitoring:
- Assess medication adherence and side effects at regular intervals 1
- Repeat STI screening as clinically indicated 2
- Monitor renal function if using tenofovir-containing regimens 1
Critical Pitfalls to Avoid
Do not delay PEP initiation for any reason—every hour counts 2, 1
Common errors include:
- Waiting for laboratory results before starting therapy 2
- Dismissing exposures beyond 72 hours without clinical judgment (in very high-risk exposures, some clinicians may still consider PEP) 2
- Failing to provide the full 28-day course upfront, leading to poor completion rates 1
- Inadequate adherence counseling, which reduces effectiveness 1
Transition to Pre-Exposure Prophylaxis (PrEP)
For MSM with ongoing HIV risk (recurrent exposures, serodiscordant partnerships, inconsistent condom use), transition to daily PrEP after completing PEP 1, 3
- Individuals requesting repeat PEP courses are ideal candidates for PrEP 2
- PrEP with tenofovir/emtricitabine taken daily reduces HIV transmission substantially when adherence is maintained 3
- Do not use sequential PEP courses for frequent exposures—this indicates need for PrEP instead 2
Special Considerations for Canada
While the evidence provided is primarily from U.S. guidelines, these recommendations are applicable in Canada where similar approaches are followed 4. Generic formulations of tenofovir/emtricitabine are now available in Canada, improving accessibility 4. Consultation with local HIV specialists or the national PEPline (888-448-4911) is available for complex cases 2.