Three prevention tools, three similar-sounding names, and a lot of confusion. PEP, PrEP, and doxyPEP do different jobs, and mixing them up can leave someone waiting when they should be acting.
This guide lays them out side by side: what each one prevents, who it is for, how it is taken, what it costs, and how to get it in Florida. If you are in an urgent situation right now, skip ahead to the PEP section.
The short version
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PrEP: ongoing protection against HIV
PrEP stands for pre-exposure prophylaxis. You take it before any exposure happens, so the medicine is already in your body if HIV shows up. According to the Centers for Disease Control and Prevention, PrEP lowers the chance of getting HIV from sex by about 99 percent when taken as prescribed, and by at least 74 percent among people who inject drugs.
How it is taken
- Daily pills. One pill a day, every day.
- Injection every two months, given by a provider.
- Injection every six months, the newest option.
How long before it works
CDC reports that PrEP pills reach maximum protection at about seven days of daily use for receptive anal sex, and about 21 days for receptive vaginal sex and injection drug use. There is no data yet on how long the shots take to reach maximum protection.
Who it is for
CDC guidance is that all sexually active adults and adolescents should be told about PrEP, and that it should be prescribed to anyone who asks for it, including people who do not report specific risk factors. You do not have to explain or justify anything to qualify.
What it does not do
PrEP does not prevent other sexually transmitted infections and it does not prevent pregnancy. It also is not the right medicine for someone who already has HIV, which is why an HIV test always comes first. If you had a recent possible exposure, read our guide to the HIV testing window period before assuming a negative result is final.
What it costs
With almost any insurance plan, PrEP and its associated visits and lab tests are free under preventive care rules. Without insurance, Florida programs, manufacturer assistance, and clinics like ours usually bring the cost down to very little. Our full breakdown is in How to Get PrEP in Florida Without Insurance.
PEP: emergency medicine after a possible exposure
This one is time sensitive
PEP must be started within 72 hours of a possible HIV exposure, and sooner is better. If that describes your situation right now, call DUG at (877) 384-6337 or walk in to the nearest clinic. Do not wait to finish reading.
PEP stands for post-exposure prophylaxis. It is antiretroviral medicine taken after a possible exposure to stop HIV from establishing itself. CDC describes PEP as being for emergency situations only, and is explicit that it must be started within 72 hours, or three days, of the exposure.
When to think about PEP
- A condom broke or slipped during sex.
- You had sex with someone whose HIV status you do not know.
- You shared needles, syringes, or other injection equipment.
- You were sexually assaulted.
- You had a possible exposure at work, such as a needlestick injury.
How it is taken
If a provider prescribes PEP, you take it daily for 28 days. Finishing the full course matters. Stopping early reduces how well it works.
What it costs
CDC notes that depending on the reason PEP is prescribed, you may qualify for free or low-cost medicine. After a sexual assault, you may be eligible for partial or full reimbursement, and the Department of Justice maintains a directory of local victim services resources. After a workplace exposure, health insurance or workers compensation usually covers it. In other cases, providers can apply to manufacturer assistance programs, and CDC notes these requests can often be handled urgently so there is no delay in getting medicine.
What PEP is not
PEP is not a substitute for ongoing prevention. CDC is clear that it is not the right choice for people who may be exposed frequently. If you have needed PEP more than once, that is a strong signal to talk about PrEP. Many people start PrEP right after finishing a course of PEP so there is no gap in protection.
DoxyPEP: an antibiotic that lowers the chance of bacterial STIs
DoxyPEP is newer than the other two and it works differently. Instead of an antiretroviral, it uses doxycycline, a common antibiotic. CDC reports that taking doxycycline within 72 hours after sex can help some people reduce their chances of getting syphilis and chlamydia, and in some studies gonorrhea.
Who CDC currently recommends it for
At this point, CDC recommends that providers discuss the pros and cons of doxyPEP with gay and bisexual men and transgender women who have had chlamydia, syphilis, or gonorrhea in the last 12 months. That is where the research shows a clear benefit. Researchers are still studying whether it helps other groups, and CDC has said it will update guidance as more is known. The full clinical recommendations are published in CDC MMWR Recommendations and Reports.
How it is taken
CDC dosing guidance is 200 mg of doxycycline as soon as possible after anal, oral, or vaginal sex, within 72 hours and ideally within 24 hours. No more than one dose in any 24-hour period, no matter how many times you have sex that day. It can be taken as often as daily if needed. Your provider will tell you how many pills make up a 200 mg dose.
Reducing side effects
CDC suggests a few practical steps that make doxycycline easier on the stomach:
- Take it with some food in your stomach.
- Take it with at least eight ounces of water and stay upright for an hour afterward.
- Avoid dairy, antacids, and supplements containing iron, calcium, or magnesium within two hours of the dose.
- Use sunscreen or cover up, since doxycycline can make some people more sensitive to the sun. In Florida that is not a small detail.
What doxyPEP does not do
DoxyPEP does not prevent HIV, herpes, or other infections outside the three bacterial STIs it targets. It is also not strong enough to treat an infection you already have. That is why regular STD and HIV testing continues alongside it, with follow-up visits every three to six months.
The open question
Because doxyPEP is relatively new, researchers are still studying its effect on the normal bacteria in the body and whether wider use could contribute to antibiotic resistance. CDC has kept its recommendations focused on the specific groups where benefit is proven, partly for that reason. It is a fair thing to ask your provider about.
Which one is right for me?
A rough decision guide. Your provider will personalize it.
- Did a possible HIV exposure happen in the last 72 hours? Ask about PEP today. This is the only one of the three with a hard deadline.
- Do you want ongoing protection from HIV? Ask about PrEP. Pills or shots, whichever fits your life.
- Are you a gay or bisexual man or a transgender woman who has had chlamydia, syphilis, or gonorrhea in the past year? Ask whether doxyPEP makes sense for you.
- Not sure where you fall? Come in and talk it through. There is no wrong question, and a provider can sort it out in one visit.
Can you use more than one?
Yes, and many people do. PrEP and doxyPEP are often used together, because they cover different infections. PEP is short-term and situational, and people frequently transition from a course of PEP straight onto PrEP. What matters is that your provider knows everything you are taking, including over-the-counter medicines and supplements, so they can check for interactions.
Side effects at a glance
- PrEP. CDC describes PrEP as safe to take. Some people have diarrhea, nausea, headache, fatigue, or stomach pain, usually early on and usually temporary.
- PEP. CDC notes PEP is safe but may cause side effects such as nausea. In almost all cases these are treatable and not life-threatening.
- DoxyPEP. Most people tolerate doxycycline well. Nausea, upset stomach, diarrhea, and sun sensitivity are the ones to watch, and the tips above help.
Our PrEP, PEP, and doxyPEP services page covers side effects and monitoring in more detail. None of these lists replace a conversation with a clinician who knows your health history.
Why this matters in Florida
Florida has consistently reported some of the highest numbers of new HIV diagnoses in the country, and bacterial STI rates have risen alongside them. The Florida Department of Health HIV and AIDS section tracks the state picture, and county health departments publish local data. Behind those figures are ordinary people who did not think prevention applied to them.
The state has worked to expand PrEP access across all 67 counties, and CDC maintains locators for PrEP and doxyPEP services and for HIV and STI testing sites. Access has improved a lot in the past few years. What has not caught up is how many people know these three tools exist, or know which one applies to them. If this article did nothing else, we hope it made that part clearer.
Getting any of the three at DUG
We provide all three at our Florida clinics, along with the HIV and STI testing that goes with them. No insurance is required, walk-ins are welcome for many services, and our South Florida clinics have bilingual staff. Care is confidential, and you can read about that on our confidential care page.
Learn more about our PrEP, PEP, and doxyPEP services, or find the clinic nearest you.
Frequently asked questions
PrEP is taken before exposure, on an ongoing basis, to prevent HIV. PEP is emergency medicine started within 72 hours after a possible exposure and taken daily for 28 days. PrEP is a plan. PEP is a response.
DoxyPEP is a 200 mg dose of the antibiotic doxycycline taken within 72 hours after sex to lower the chance of getting syphilis, chlamydia, and in some studies gonorrhea. CDC currently recommends discussing it with gay and bisexual men and transgender women who have had one of those infections in the past 12 months.
Many people do, because they prevent different infections. Talk to your provider so they can review your full medication list and set up the right follow-up schedule.
PEP is unlikely to be effective after 72 hours, but you should still be seen. A provider can arrange HIV testing on the right schedule, treat anything else that needs treating, and talk with you about starting PrEP going forward.
No. DoxyPEP is an antibiotic and antibiotics do not work on HIV. PrEP and PEP are the tools for HIV.
No single tool covers everything. PrEP and PEP cover HIV. DoxyPEP covers three bacterial STIs. Condoms add protection against infections none of them reach, and against pregnancy.
The fastest route is a visit. A provider will review your history, run any testing needed, and tell you what you can start on. You can book an appointment online or call (877) 384-6337.
Talk it through with a provider
Prevention options explained in plain language. No insurance required. Walk-ins welcome for many services.
Medical disclaimer
This article is for informational purposes only and is not a substitute for professional medical advice. Always consult a licensed clinician for personal health concerns.
References
Sources are limited to government and nonprofit health authorities.
- Preventing HIV with PrEP. Centers for Disease Control and Prevention, updated April 2026.
- Preventing HIV with PEP. Centers for Disease Control and Prevention.
- Preventing STIs with Doxy PEP. Centers for Disease Control and Prevention, updated November 2025.
- Guidelines for the Use of Doxycycline Post-Exposure Prophylaxis for Bacterial STI Prevention. CDC MMWR Recommendations and Reports.
- CDC Recommends New Injectable HIV PrEP. HIV.gov, U.S. Department of Health and Human Services.
- PrEP and PEP. Florida Department of Health.
- Find Doxy PEP Services and Find HIV and STI Testing. Centers for Disease Control and Prevention.