PrEP is for any HIV-negative person who has an ongoing chance of HIV exposure — through sex with partners whose status they don't know, with a partner living with HIV, or through sharing injection equipment. Current CDC guidance offers it across all of these risk groups, including but not limited to gay and bisexual men CDC, Talk PrEP Together.
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 PrEP is and how it works
PrEP stands for pre-exposure prophylaxis — medicine that HIV-negative people take before a possible exposure to keep the virus from ever taking hold. The drug builds up in the tissues most likely to come into contact with HIV, so that if the virus shows up, it can't establish an infection.
That timing trips most people up. PrEP only works when it's already in your system on an ongoing schedule, so it isn't a morning-after pill. If you've had a single, unexpected exposure and aren't already on PrEP, the emergency option is PEP (post-exposure prophylaxis), a different regimen started quickly after the fact CDC, Preventing HIV with PEP.
How well does PrEP work?
Taken as prescribed, PrEP reduces the risk of getting HIV from sex by about 99 percent. For people whose risk comes from injection drug use, the pills lower the risk by at least 74 percent when taken consistently. "As prescribed" is doing a lot of work in those numbers, because protection drops off fast if doses get skipped.
Protection also isn't instant. The medicine needs time to reach full levels in different tissues:
- For receptive anal sex, maximum protection takes about 7 days of daily dosing.
- For receptive vaginal sex and for injection drug use, it takes about 21 days to reach full protection.
- In that ramp-up window, keep using condoms or another backup method.
Who should take PrEP — and which kind
The MSM-only idea is a myth. PrEP is appropriate for anyone HIV-negative who has a real, ongoing chance of exposure. That includes people whose partner is living with HIV, people with multiple partners or partners of unknown status, people who don't consistently use condoms with partners at higher risk, and anyone who shares needles, syringes, or other injection equipment. Cisgender women, transgender people, and heterosexual men all qualify under the same logic, based on exposure.
There are three FDA-approved options, and which fits depends on your body and how your risk happens:
| Option | Form | Who it's for |
|---|---|---|
| Truvada | Daily oral pill | People at risk through sex or injection drug use |
| Descovy | Daily oral pill | People at risk through sex only — not for those assigned female at birth who are at risk through receptive vaginal sex |
| Apretude (cabotegravir) | Injection | People at risk through sex who weigh at least 77 pounds (35 kg), and who'd rather not take a daily pill |
The pill choice often comes down to how your risk happens and a few personal factors; if you're weighing the two daily options, here's a fuller look at truvada vs descovy for prep. Apretude is worth raising with your clinician if remembering a daily pill is the part that trips you up, since an injection on a set schedule sidesteps that entirely.
What starting PrEP is actually like
In practice, getting on PrEP is straightforward. It starts with an HIV test — you have to be HIV-negative to begin, since starting PrEP with an undiagnosed infection can cause resistance. After that, you'll have regular check-ins while you stay on it, typically including repeat HIV testing and a few labs to make sure the medicine is treating your kidneys kindly. Family doctors, sexual-health clinics, and telehealth services all prescribe it, so you don't need a specialist.
Cost and how to get it
Cost keeps a lot of people from starting, and it shouldn't. Most insurance covers PrEP, and for people who are uninsured or underinsured, manufacturer programs and federal and state assistance programs exist specifically to cover the medication and often the lab visits too. A clinic or telehealth provider can point you to the right one when they write the prescription.
What PrEP does NOT protect against
PrEP is built for one job: HIV. It does nothing against other sexually transmitted infections like chlamydia, gonorrhea, or syphilis, and it doesn't prevent pregnancy. The second big mistake people make is assuming PrEP covers everything, so people on PrEP should keep up routine STI testing.
How PrEP fits with the rest of your prevention
Think of PrEP as one strong layer, not the whole wall. Because it leaves other STIs on the table, regular screening stays part of the plan — most people on PrEP already test at their check-in visits, and it's easy to get tested alongside those appointments. Condoms still add protection against the infections PrEP misses, and vaccines (for hepatitis B and HPV, for instance) cover ground neither one does.
PrEP also fits into the bigger picture of HIV prevention. When people living with HIV are on effective treatment, the virus becomes untransmittable through sex, so earlier hiv treatment can help prevention works hand in hand with PrEP across a community. If you've had a specific exposure and aren't sure of your timing, knowing when to test after exposure helps you and your clinician decide whether you need PEP now and PrEP going forward.
When to talk to a clinician
If any of the risk situations above sound like your life, that's reason enough to bring up PrEP at your next visit; you don't need to wait for a scare. Raise it sooner rather than later if your partner is living with HIV, if you share injection equipment, or if your risk has recently gone up. And if you think you've already been exposed, don't wait for a PrEP appointment — call about PEP right away, because that window is short.