HIV Post-Exposure Prophylaxis: What It Is and How It Works

When you’re exposed to HIV post-exposure prophylaxis, a short-term treatment used to prevent HIV infection after a possible exposure. Also known as PEP, it’s not a vaccine—it’s an emergency intervention that can stop the virus from spreading in your body if started within 72 hours. This isn’t something you take daily like a vitamin. It’s a 28-day course of antiretroviral drugs, usually two or three pills a day, meant for people who had a single high-risk event—like a needlestick injury, unprotected sex with someone who has HIV, or sexual assault.

PEP works by blocking HIV from making copies of itself in your cells. The sooner you start, the better the chance it works. After 72 hours, the virus may have already settled into your system, making PEP much less effective. That’s why people who think they’ve been exposed should go to an ER, urgent care, or clinic right away. You don’t need a confirmed HIV-positive contact to start PEP—doctors will assess your risk and act fast. Many clinics keep PEP on hand because time is everything.

It’s not for everyone. If you’re regularly exposed to HIV—like through unprotected sex with an HIV-positive partner—PEP isn’t the right long-term solution. That’s where PrEP (pre-exposure prophylaxis) comes in. But if you had one scary moment, PEP is your safety net. Side effects like nausea, headaches, or fatigue are common but usually mild and temporary. Most people tolerate it well enough to finish the full course.

What you’ll find in this collection are real-world guides on how PEP fits into broader HIV care. You’ll read about atazanavir, an antiretroviral drug used in HIV treatment and sometimes in PEP regimens, and how it’s used in global health programs. You’ll also see comparisons between different HIV medications, like how sildenafil, commonly used for erectile dysfunction isn’t related to PEP but shows how people often mix up HIV drugs with other prescriptions. There’s no fluff here—just clear, practical info on what PEP is, when it’s needed, what drugs are involved, and how to get it without delay.

If you’ve had a recent exposure, don’t wait. PEP works best when taken fast. And if you’re just trying to understand how it all fits together, these posts break down the science, the timing, and the real-life choices people face. No jargon. No guesswork. Just what you need to know.