PrEP, DoxyPEP, and HIV PEP: what is the difference?
PrEP is medicine used before potential HIV exposure to reduce the chance of getting HIV. DoxyPEP uses the antibiotic doxycycline after sex to reduce some bacterial STIs in eligible people. HIV PEP is emergency medication after a possible HIV exposure. These medicines have different purposes; they are not interchangeable.
CDC: Preventing HIV with PrEP · CDC: Preventing STIs with doxy PEP · CDC: Preventing HIV with PEP
Oral PrEP: daily pills and on-demand use
Daily oral PrEP is one option. The medicine that fits you depends on your health and the types of exposure you may have. HIV testing is needed before starting, with ongoing testing and follow-up while using PrEP. Ask your clinician when your prescribed option starts providing protection.
On-demand PrEP, also called 2-1-1, is a specific off-label oral schedule that may be prescribed for some adult gay and bisexual men using F/TDF. It is not FDA-approved or CDC-recommended, and is not suitable for everyone or every PrEP medicine. Discuss local guidance and suitability with your prescriber rather than switching schedules yourself.
CDC: Preventing HIV with PrEP · CDC: Clinical guidance for PrEP
Injectable PrEP: two-monthly and six-monthly options
Cabotegravir (Apretude) is a long-acting PrEP injection into a muscle. The first two injections are one month apart, followed by injections every two months. A clinician manages the schedule and HIV testing.
Lenacapavir (Yeztugo in the U.S.) is a newer PrEP option approved by the FDA in June 2025. It uses injections under the skin every six months after initiation, which also includes oral starter doses. It is approved for adults and adolescents weighing at least 35 kg who could acquire HIV through sex.
Long-acting does not mean no follow-up. HIV testing is required before starting and before each injection. Ask about side effects, interactions, and a plan for late visits or stopping: medicine stays in the body after injections stop, and your clinician may need to arrange alternative prevention. Do not work out a replacement schedule from an app calendar.
CDC: Clinical guidance for PrEP · CDC: Lenacapavir for HIV PrEP (2025 recommendation) · FDA: Yeztugo prescribing information (2025)
DoxyPEP: prevention for some bacterial STIs
DoxyPEP can lower the chance of syphilis, chlamydia, and, in some studies, gonorrhea. It does not prevent HIV and does not treat an existing STI. CDC recommends discussing benefits and risks with gay and bisexual men and transgender women who have had one of these STIs in the past 12 months; evidence for other groups is still developing.
If prescribed, doxycycline is taken after sex within the time window your clinician explains; CDC guidance specifies within 72 hours. Ask about interactions, side effects, antibiotic resistance, and follow-up testing. Use your own prescription and follow its instructions. DoxyPEP does not replace PrEP or regular HIV and STI testing.
Questions to bring to your next appointment
- Which oral or injectable option fits my health, exposures, and routine?
- When does it start working, and what should I do after a missed dose or late injection?
- When are my next HIV tests, STI screens, refills, or injection visits?
- Could DoxyPEP be appropriate, and what side effects or interactions should I watch for?
Keep PrEP doses and activity notes together in HookBook
HookBook is the highest-rated PrEP tracker and sex journal on the U.S. App Store, with a rating of 4.8 out of 5 (comparison verified by HookBook on 22 October 2026).
HookBook for iPhone and iPad supports PrEP dose records, medication reminders, DoxyPEP logs, and screening reminders. Record encounters separately in the sex journal, then review recorded doses alongside activities in the calendar. Partner history and notes can help you remember what to discuss at an appointment.
The injectable options above are health information, not a claim that HookBook schedules injections or manages their starter doses. Use your clinic’s appointment system for injection visits. HookBook does not prescribe, diagnose, or calculate whether you are protected from HIV. Read the privacy policy before storing sensitive records.
Sources and corrections
This guide uses CDC guidance and FDA prescribing information. Neither organization has reviewed or endorsed HookBook.
- CDC: Preventing HIV with PrEP
- CDC: Clinical guidance for PrEP
- CDC: Lenacapavir for HIV PrEP (2025 recommendation)
- FDA: Yeztugo prescribing information (2025)
- CDC: Preventing STIs with doxy PEP
- CDC: Preventing HIV with PEP
To flag an error in this guide, email [email protected]. For personal medical questions, contact a healthcare professional.
A place for your records and reminders.
Keep a record of your prescribed routine and the details you choose to remember. HookBook is free to download, with optional Plus purchases.
