What's the difference between Doxy-PEP, PrEP, and PEP? A Comparative Guide to HIV and STI Prevention Medications | Mona Aoyama Clinic
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July 3, 2026
DoxyPEP, PrEP, and PEP: What's the Difference? A Comparison of HIV and STI Prevention Medications
"What's the difference between DoxyPEP and PEP?" "I thought PrEP would also prevent STIs." "I don't know which one to use." — There are multiple medications for STI prevention, and many people find them confusing.
DoxyPEP, PrEP, and PEP each have entirely different target infections, timing of use, and purposes. To choose the prevention method that suits your situation, it is essential to correctly understand their differences.
In this article, a doctor from Mona Aoyama Clinic will explain the differences between the three prevention medications in an easy-to-understand comparison table, helping you clarify which medication you need.
- Prescriptions for DoxyPEP, PrEP, and PEP are all available
- Online consultations for combination prescriptions are also accepted
- Same-day prescription and same-day shipping (for payments made by 4 PM)
Three Prevention Medications — Comparison Table
| Item | DoxyPEP | PEP | PrEP |
|---|---|---|---|
| Purpose | STI prevention (post-exposure) | HIV prevention (post-exposure) | HIV prevention (pre-exposure, continuous) |
| Active Ingredients | Doxycycline | Tenofovir + Emtricitabine (+ Integrase Inhibitor) | Tenofovir + Emtricitabine |
| Timing of Use | Within 72 hours of sexual activity, one dose | Within 72 hours of sexual activity, daily for 28 days | Daily continuous use before and during sexual activity |
| Target Infections | Chlamydia, Syphilis, Gonorrhea | HIV | HIV |
| Effectiveness against HIV | None | High (approx. 80-90%+) | High (approx. 99% with daily use) |
| Impact of Missed Doses | Single dose, less likely to forget | Must be taken daily, forgetting reduces effectiveness | Must be taken daily, forgetting reduces effectiveness |
| Prescription Method | Our clinic: Online prescription, same-day shipping | Our clinic: Online prescription, same-day shipping | Our clinic: Online prescription, regular prescription |
Who Each Medication Is For
DoxyPEP is suitable for:
- Individuals who have had unprotected sex and are concerned about chlamydia, syphilis, or gonorrhea
- Individuals who have had an STI within the past 12 months
- Individuals using PrEP but are concerned about STIs other than HIV
- MSM (men who have sex with men) or transgender women
PEP is suitable for:
- Individuals who have had sex with HIV exposure risk and are within 72 hours
- Individuals whose condom broke or slipped during sex with an HIV-positive person
- Individuals in an emergency situation requiring immediate HIV prevention
PrEP is suitable for:
- Individuals who have ongoing sexual activity with HIV risk (and can adhere to daily use)
- Individuals who have sex with an HIV-positive partner
- Individuals who frequently use PEP (consider switching to PrEP)
If You're Concerned About Both HIV and STIs
DoxyPEP and PEP can be used simultaneously. If there is a risk of both HIV exposure and exposure to chlamydia, syphilis, etc. (e.g., unprotected sex with multiple partners), combining both can provide broad prevention.
💡 To PrEP users: While PrEP prevents HIV, it is not effective against chlamydia, syphilis, or gonorrhea. Using DoxyPEP concurrently with PrEP can cover overall STI prevention. Our clinic offers combination plans.
Cost Comparison (Our Clinic)
| Medication | Estimated Cost (incl. tax) | Duration of Use |
|---|---|---|
| DoxyPEP (3 doses) Regular | ¥7,500/month | One dose as needed |
| PEP (28 days) | Please inquire separately | Daily for 28 days |
| PrEP (1 month) Regular | Please inquire separately | Daily continuous use |
* Please check each product page for the latest prices.
Frequently Asked Questions
No, it cannot. PrEP only prevents HIV. DoxyPEP is needed to prevent chlamydia, syphilis, and gonorrhea. Concurrent use of DoxyPEP is recommended for PrEP users.
Yes, it is. If you are concerned about both HIV and other STIs, both can be prescribed. Our clinic offers online consultation and prescription for both.
If you are using PEP more than once a month, it is worth considering switching to PrEP. PrEP, when taken daily, has very high HIV prevention effectiveness. Please consult with us during your examination.
Related Columns
What is DoxyPEP? A doctor explains the STI prevention medication taken within 72 hours after sex What to do after unprotected sex — How to act within 72 hours using DoxyPEP and PEP Prevention plan combining regular STI testing and DoxyPEPClinic Hours / Access (Online Consultation)
| Clinic Name | Mona Aoyama Clinic | ||
| Consultation Type | Online consultation (nationwide) / In-person consultation (Aoyama, Tokyo) | ||
| Location | 3F D Building, 1-10-3 Minami Aoyama, Minato-ku, Tokyo 107-0062 | ||
| Nearest Station | 5-minute walk from Tokyo Metro "Aoyama-itchome Station" | Online Consultation | 24-hour reception, same-day shipping available (for payments made by 4 PM) |
Consult with us for DoxyPEP, PrEP, and PEP
Online consultations available nationwide. Same-day prescription and same-day shipping (for payments made by 4 PM).