Do I need post‑exposure prophylaxis after pre‑ejaculate entered my vagina from a partner who is HIV‑positive on stable antiretroviral therapy with an undetectable viral load and who has intact vaginal mucosa?

Post-Exposure Prophylaxis is NOT Routinely Recommended for Pre-Ejaculate Exposure from an HIV-Positive Partner with Sustained Viral Suppression

You do not need nPEP in this scenario because your partner has an undetectable viral load on stable antiretroviral therapy, which means they cannot transmit HIV to you sexually (U=U: Undetectable = Untransmittable). 1

Why nPEP is Not Indicated Here

According to the most recent 2025 CDC guidelines, nPEP is not routinely recommended when the source person has sustained viral suppression on antiretroviral therapy, regardless of the type of sexual exposure (vaginal, anal, or pre-ejaculate contact). 1 The guidelines explicitly categorize exposures from virally suppressed sources in the "nPEP not routinely recommended" category. 1

The U=U Principle

• When an HIV-positive person maintains an undetectable viral load through consistent ART adherence, they cannot sexually transmit HIV to partners. 1
• "Sustained viral suppression" means the source has maintained undetectable viral loads over time with good ART adherence. 1
• This applies to all types of sexual contact, including vaginal intercourse with or without ejaculation, and includes pre-ejaculate fluid exposure. 1

When nPEP WOULD Be Recommended

nPEP is only recommended within 72 hours when the HIV-positive source has: 1

• Known viremia (detectable viral load), OR
• Unknown viral suppression status (not on ART, poor adherence, or viral load unknown)

For vaginal intercourse without a condom from a source with known viremia or unknown suppression status, nPEP should be initiated as soon as possible, ideally within 24 hours but no later than 72 hours post-exposure. 1, 2

Critical Caveats

Confirm Viral Suppression Status

Before declining nPEP, you must verify that your partner: 1

• Is currently taking ART consistently (not missing doses)
• Has recent viral load testing showing undetectable levels (typically <50 copies/mL)
• Has maintained suppression over time (not just one isolated test)

If you cannot confirm sustained viral suppression, treat this as an unknown suppression status and initiate nPEP immediately. 1

The 72-Hour Window

• Animal studies show that PEP efficacy decreases dramatically with delayed initiation. 1
• Macaque studies demonstrated 100% protection when PEP started at 12-36 hours, but only 75% protection at 72 hours post-vaginal HIV exposure. 1
• If you have any doubt about your partner's viral suppression status, do not wait—initiate nPEP immediately. 1, 2

If You Need nPEP (For Future Reference)

Should you ever have an exposure from a source with detectable or unknown viral load: 1, 2

• Preferred regimen: Bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) for 28 days 1, 2
• Alternative: Dolutegravir + (tenofovir alafenamide OR tenofovir disoproxil fumarate) + (emtricitabine OR lamivudine) 1
• Follow-up HIV testing: At 4-6 weeks and 12 weeks post-exposure 1, 2

Consider PrEP Instead

If you have ongoing sexual activity with an HIV-positive partner (even one with viral suppression) or other HIV risk factors, pre-exposure prophylaxis (PrEP) may be more appropriate than repeated nPEP courses. 1, 2 PrEP provides continuous protection and should be discussed with your healthcare provider. 1, 2

Consultation Resources

For case-by-case guidance when viral suppression status is uncertain: 1

• National PEPline: 888-448-4911
• UCSF National Clinician Consultation Center: https://nccc.ucsf.edu/clinician-consultation/pep-post-exposure-prophylaxis