PrEP: HIV Prevention Medication, Explained

What it actually is, and how well it works

There are two FDA-approved forms today: a daily oral pill (tenofovir/emtricitabine, brand name Truvada or generic, and Descovy — though Descovy specifically is not approved for receptive vaginal sex, since the trials supporting it didn't include enough cisgender women to establish that use, which is worth knowing since it's often advertised alongside Truvada as if interchangeable), and a long-acting injectable (cabotegravir, brand name Apretude, given every two months after two monthly starter doses).

Taken consistently, oral PrEP reduces the risk of getting HIV from sex by about 99%. The injectable version has shown even higher effectiveness in real-world use, largely because it removes daily adherence as a point of failure.

Who it's for — broader than the conversation usually suggests

The CDC recommends that anyone sexually active who wants additional HIV prevention can have this conversation with a provider — it isn't restricted to a pre-identified "high-risk" group. Specific situations worth raising it in: a partner who is HIV-positive or whose status you don't know, inconsistent condom use, a recent STI diagnosis (a marker worth discussing, not a disqualifier), or shared injection equipment.

PrEP conversations have historically centered on gay and bisexual men, but women account for a meaningful share of new HIV diagnoses in the US and are both eligible for and, relative to men, underprescribed PrEP — worth naming directly, since it shapes whether this even comes up at a routine visit.

What starting it actually involves

Starting requires a negative HIV test immediately beforehand — PrEP is not a treatment for an existing infection, and taking it with an undiagnosed infection already present can lead to drug resistance. While on oral PrEP, follow-up HIV testing roughly every three months is standard, along with baseline and periodic kidney-function monitoring and routine STI screening.

Cost: PrEP medication and the required lab visits and testing are generally required to be covered with no cost-sharing under most insurance plans as a preventive service. For the uninsured, manufacturer and nonprofit assistance programs (such as Ready, Set, PrEP and Gilead Advancing Access) can provide it free or low-cost — worth asking a provider or clinic about directly rather than assuming it's unaffordable.

Pregnancy, breastfeeding, and PrEP

Current guidance supports continuing or starting oral PrEP during pregnancy and while breastfeeding for people with ongoing risk, since acquiring HIV during pregnancy carries real transmission risk to the baby. Worth raising explicitly at a prenatal visit if you're trying to conceive or already pregnant with a partner who is HIV-positive or whose status is unknown — this isn't always brought up proactively.

Side effects, and how this differs from PEP

Most people on oral PrEP have no side effects beyond mild, temporary GI symptoms in the first few weeks; there's no evidence it affects fertility.

Don't confuse PrEP with PEP (post-exposure prophylaxis) — an emergency short course started within 72 hours after one specific exposure, not something taken on an ongoing basis. If you've had a specific recent exposure, PEP — not PrEP — is the urgent question, and it needs same-day or next-day care, not a conversation to schedule for later.