- Five routes, one goal: daily pill, 2-monthly shot, twice-yearly shot, on-demand, or the ring.
- Time to protection differs — ~7 days (anal) to ~20 days (vaginal) on daily pills.
- Missed a dose? Pills are forgiving; injections have a window; 2-1-1 needs the pre-dose.
- Add Doxy-PEP to cut bacterial STIs — PrEP covers HIV only.
01The 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.
02Time 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 |
03Missed 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.
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.
04Doxy-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.
Notes: pairs safely with all PrEP (see the interaction checker). Watch for sun sensitivity; evidence in cisgender women is still limited. It does not replace regular STI testing. Full guide: Doxy-PEP →
05Special 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.
⚧ 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.
06Frequently asked questions
QWhich PrEP option is best?
There's no single best — it depends on your body, exposures and lifestyle. Daily generic Truvada is cheapest and most flexible; the injections suit people who'd rather not take a daily pill; 2-1-1 suits infrequent, plannable anal sex. Decide with a provider.
QHow fast am I protected?
On daily pills, about 7 days for anal sex and 20 days for vaginal sex. Injections protect on schedule once the series is started. Use condoms until you're covered.
QCan I switch between options?
Yes — many people move between pills and injections (or back). Your provider plans the timing so there's no gap in protection.
QDoes any PrEP protect against other STIs?
No — PrEP is HIV-only. Add regular STI testing, condoms and, where appropriate, Doxy-PEP.
Related
🔬 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 · 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.