Condoms and PrEP solve different problems. Condoms are a physical barrier that blocks many STDs — chlamydia, gonorrhea, syphilis, HIV — plus pregnancy. PrEP is a daily pill or shot that stops HIV only. For the strongest protection, use both: PrEP for near-total HIV defense, condoms for everything else.
risk reduction, taken as prescribed
daily Truvada/Descovy or the Apretude injection
not other STIs or pregnancy
| Item | Value |
|---|---|
| From sex | ~99% — risk reduction, taken as prescribed |
| From injection use | ≥74% |
| Forms | pill or shot — daily Truvada/Descovy or the Apretude injection |
| Protects against | HIV only — not other STIs or pregnancy |
What each one is
Condoms are a barrier method. Worn correctly and consistently, they keep semen, vaginal fluid, and blood from passing between partners, which is how most STDs spread. Because they physically separate the genitals, they reduce the risk of a broad range of infections at once, and they prevent pregnancy.
PrEP stands for pre-exposure prophylaxis. It's medicine that HIV-negative people take before possible exposure to keep HIV from taking hold in the body CDC PrEP. You take it while you're HIV-negative, on an ongoing schedule. You can learn how the pill and shot options stack up in our guide to prep for hiv prevention.
PrEP is not a morning-after option. The emergency drug you take after a single possible exposure is PEP, and the two aren't interchangeable CDC PEP. PrEP is the everyday seatbelt; PEP is the airbag after a crash.
The key differences
What they protect against
PrEP protects against HIV and nothing else. It does not prevent chlamydia, gonorrhea, syphilis, or any other STI, and it does not prevent pregnancy. Condoms cover all of those at once. If you rely on PrEP alone, you're well-protected from HIV but still exposed to bacterial and viral STIs, so people on PrEP are advised to keep testing regularly.
How well they work
Taken as prescribed, PrEP reduces the risk of getting HIV from sex by about 99%. For people at risk through injection drug use, the pills reduce the risk by at least 74% when taken as prescribed. Condoms don't have a single tidy percentage like that, because effectiveness depends heavily on using one correctly every single time. Used consistently and correctly, they meaningfully lower the risk of the STDs PrEP can't touch.
Timing — when protection kicks in
A condom works the moment it's on. PrEP takes time to build up in the body, and how long depends on the type of exposure: about 7 days for receptive anal sex, and about 21 days for receptive vaginal sex and injection drug use. So you have to start it before you need it.
What you actually have to do
Condoms require nothing but having one on hand and using it each time. PrEP is a medical commitment: an HIV test before you start, then regular check-ins while you're on it. Daily oral options include Truvada, for people at risk through sex or injection drug use, and Descovy, for those at risk through sex only — though Descovy isn't approved for people assigned female at birth who are at risk through receptive vaginal sex. If a daily pill isn't your style, Apretude is an injectable form of PrEP (cabotegravir) for people at risk through sex who weigh at least 77 pounds.
Condoms vs PrEP at a glance
| Condoms | PrEP | |
|---|---|---|
| Protects against HIV | Yes | Yes — about 99% from sex when taken as prescribed |
| Protects against other STIs | Yes (chlamydia, gonorrhea, syphilis, and more) | No |
| Prevents pregnancy | Yes | No |
| When it works | Immediately, when worn correctly | After ~7 days (anal) or ~21 days (vaginal/injection) |
| What's required | Have one and use it every time | HIV test first, ongoing pill or shot, regular check-ins |
| Forms | External and internal condoms | Daily pills (Truvada, Descovy) or a shot (Apretude) |
Which one applies to you
These cover different gaps, and most people benefit from layering them.
- You want broad STD and pregnancy protection: condoms are the tool that does both in one move.
- You have an ongoing risk of HIV — through sex with partners whose status you don't know, or through injection drug use — PrEP gives you near-total HIV protection that a slipped or forgotten condom can't undo.
- You want the strongest possible protection: use both. PrEP guards against HIV even if a condom fails, and condoms cover the STIs PrEP ignores.
- You had a single possible exposure already: PrEP won't help retroactively. That's a PEP conversation, and it's time-sensitive, so reach out fast.
If you're managing HIV risk in a relationship where one partner is positive, treatment matters too. An undetectable viral load means the virus can't be passed on sexually, which is why earlier hiv treatment can help prevention.
The practical next step
Starting PrEP isn't complicated. You'll need an HIV test first to confirm you're negative, then a prescription from a clinic or a telehealth service, plus periodic visits to recheck your HIV status and overall health while you're on it. Cost shouldn't be a barrier: assistance programs exist to cover PrEP, and many clinics will help you find one.
Whether or not you go on PrEP, regular testing keeps the rest of your sexual health on track, especially the STIs PrEP doesn't cover. It's easy to get tested, and if you've had a recent exposure, check our guide on when to test after exposure so you test at the right moment rather than too early.
When to talk to a clinician
Bring it up with a clinician if your HIV risk has changed, if you're thinking about starting or stopping PrEP, if you've had a possible exposure in the last few days and want to ask about PEP, or if you notice any STI symptoms. A common mistake is assuming PrEP makes routine STI testing unnecessary; it doesn't, so people on PrEP still test regularly. Your clinician can match the right tool to your actual situation.