Short answer
PrEP is prevention for ongoing HIV risk: daily pills or scheduled injections keeping HIV-negative people negative at 99%+ efficacy when taken as directed. Prescribed after risk assessment and confirmed HIV-negative status, monitored throughout use.
Anyone with ongoing HIV exposure risk (condomless sex outside tested monogamy, recent bacterial STIs, shared injection equipment, serodiscordant partnerships) deserves a PrEP conversation; curiosity alone qualifies. No risk threshold gates the discussion.
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See Tests & Prices →Candidacy map. Who benefits most
Serodiscordant partnerships (HIV-positive partner, HIV-negative partner: PrEP protecting the negative partner alongside the positive partner’s treatment).
Condomless anal or vaginal sex with partners of unknown status. Recent bacterial STIs (syphilis, gonorrhea, chlamydia diagnoses mark networks and behaviors where HIV travels next. Guidelines flag these explicitly).
Transactional sex contexts.
Injection equipment sharing. Anyone anxious enough about HIV to use prevention consistently. Sustained anxiety is itself a candidacy signal, since adherent PrEP resolves it.
Assessment is nonjudgmental and brief; under-disclosure (minimizing risk to the clinician) is the main barrier to accurate candidacy. Candor serves dosing and modality choice.
Modalities. Matched to life patterns
- Daily oral TDF/FTC or TAF/FTC (kidney and bone profiles differ: TAF gentler on kidneys and bones, TDF longer-tracked and cheaper generically; continuous protection with forgiveness for occasional late doses).
- Event-driven (2-1-1) dosing for eligible MSM per guidance (strict timing protocol around exposures. Confirm current eligibility, since criteria evolve).
- Long-acting injectable cabotegravir (clinic injections on schedule. For adherence-challenged users, privacy-constrained users with no pill bottles at home, or anyone preferring injections to dailies).
Efficacy parity holds across modalities when used as directed; lifestyle fit predicts adherence better than willpower.
The MSM-specific discussion lives at PrEP Discussions for MSM.
Starting protocol. Baselines before the first dose
Confirmed HIV-negative status including acute-infection review (starting PrEP during undiagnosed acute HIV breeds resistance. Symptom and exposure review precedes every start).
Kidney function (creatinine/eGFR baselines, monitored on oral PrEP).
Hepatitis B screening (stopping TDF/FTC later flares chronic HBV. Plan accordingly before discontinuation scenarios).
STI baseline panel (multi-site NAAT plus serology: PrEP visits double as screening vehicles).
Pregnancy discussion where relevant.
Adherence planning (routine-anchored dosing, reminder systems, backup supply).
Staying on PrEP. Monitoring that sustains safety
Scheduled HIV testing (catching breakthroughs early. Rare but managed urgently when found).
Kidney function and STI screens on protocol intervals.
Pregnancy testing where relevant.
Adherence supports (non-shaming reviews. Missed doses are data for regimen adjustment, possibly toward injectable).
Side-effect management (startup nausea typically fades within weeks; persistent issues trigger formulation switches, not abandonment).
Cost navigation through insurance plus manufacturer and 340B assistance programs. Cost navigators resolve nearly all affordability blocks.
When to seek care
To assess candidacy anytime risk exists, for initiation workups, with adherence struggles or side effects, and immediately for exposures during PrEP gaps (PEP evaluation).