Which PrEP is right for you? Pills, injections & on-demand.
There is no longer just one PrEP. You can choose daily pills, a 2-monthly injection, a new twice-a-year injection, or on-demand dosing around sex. Here's how they compare — with the two questions people ask most: how long until I'm protected? and what if I miss a dose?
The 5 main regimens
Same goal — keep you HIV-negative. They differ in how you take them, who they're approved for, and how fast they work.
⏱️ Time to protection — at a glance
How long after starting before you're actually protected. Until then, use condoms.
| Option | Anal sex | Vaginal / front-hole | Key caveat |
|---|---|---|---|
| Truvada (daily) | ~7 days | ~20 days | Approved for all exposures |
| Descovy (daily) | ~7 days | Not established | Not approved for vaginal sex |
| Apretude (2-monthly) | Protective on schedule once the series is started | Keep the ±7-day window | |
| Lenacapavir (6-monthly) | After completing the initiation schedule | Twice-yearly maintenance | |
| 2-1-1 (on-demand) | Pre-dose 2–24 h before | Not for vaginal sex | MSM / anal sex only |
💊 Missed a dose? Quick reference
Daily pills (Truvada / Descovy)
Take the missed pill when you remember (don't double up excessively). For anal sex, 4+ pills a week keeps you protected; for vaginal sex you need near-daily dosing. If you've missed many days, talk to your provider about restarting.
Injections (Apretude / Lenacapavir)
Each shot has a dosing window (Apretude ±7 days; lenacapavir every 6 months). If you'll be late, ask for oral bridging so there's no gap. A missed window means lost protection — set a reminder for the next appointment.
2-1-1 on-demand
If you miss the pre-dose (the "2"), you are not protected for that episode — use condoms and consider PEP. Keep taking 1 pill daily until 48 h after the last sex.
Not sure you're covered?
If a recent exposure may have outrun your protection, you may need PEP within 72 hours. When in doubt, get seen.
🛡️ Doxy-PEP — lowering STI risk
PrEP protects against HIV, but not other STIs. Doxy-PEP is a single dose of the antibiotic doxycycline taken after sex to cut the risk of bacterial STIs — a newer tool now backed by CDC guidance.
Special situations
🤰 Pregnancy & breastfeeding
If you're at ongoing risk, staying on PrEP in pregnancy is recommended — HIV in pregnancy is far riskier than PrEP. Truvada has the most data; discuss the injectables individually.
🚺 Cisgender women & vaginal sex
Use Truvada, Apretude, or Lenacapavir — all approved for vaginal exposure. Descovy and 2-1-1 are NOT for vaginal sex. Vaginal tissue also needs ~20 days on daily pills to be protected.
⚧ Transgender & gender-diverse
PrEP works with hormone therapy — no interaction with oestrogen, testosterone or blockers (confirm in the checker). All options are available; choose by exposure type and preference.
💉 People who inject drugs
Truvada, Apretude and Lenacapavir all protect against injection-related HIV. Combine with sterile equipment and other harm-reduction support.
🔬 Sources & review
- U.S. CDC — PrEP Clinical Practice Guideline (2021) and Doxy-PEP Guidelines (2024).
- WHO — Consolidated Guidelines on HIV Prevention (2021, with 2022–2024 updates on event-driven and long-acting PrEP, and the dapivirine ring).
- USPSTF — PrEP Recommendation Statement (2023).
- U.S. FDA — labelling for Truvada, Descovy, Apretude (2021) and Yeztugo / lenacapavir (2025); IPERGAY & PURPOSE trial reports.
✔ Last medically reviewed: 3 July 2026 · Prepmedication.com Medical Review Team · Next review due: January 2027 · Editorially independent (no manufacturer funding) · How we review →
Medical disclaimer. This page is general information, not a diagnosis or prescription. Approvals, dosing and availability vary by country and change over time — always confirm your plan with a healthcare professional. If you may have been exposed to HIV in the last 72 hours, see PEP now.
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