Syphilis Is Soaring: A Doctor Explains Infection Routes, Symptoms, and DoxyPEP Prevention | Mona Aoyama Clinic
目次
August 3, 2026
Syphilis is rapidly increasing - A doctor explains everything from routes of infection and symptoms to prevention with DoxyPEP
Many of you might have thought, "Isn't syphilis a disease of the past?" However, currently, the number of syphilis patients in Japan continues to increase to record-high levels, spreading among young people, women, and men alike.
Syphilis is often hard to notice due to mild initial symptoms, and if left untreated, it can cause severe damage to the heart, brain, and nerves years later. Furthermore, if a pregnant woman is infected, it can affect the baby as congenital syphilis.
In this article, a doctor from Mona Aoyama Clinic explains the current situation of syphilis, its routes of infection, symptoms, testing, treatment, and even prevention with DoxyPEP.
- Syphilis testing and DoxyPEP prescription are both available online
- Testing can be done from home with a mail-in test kit
- Same-day prescription and same-day shipping (for payments made by 4 PM)
Syphilis infection status in Japan - Why is it increasing now?
According to data from the National Institute of Infectious Diseases, the number of syphilis patients in Japan has been rapidly increasing since the 2010s, with over 10,000 cases reported annually in 2023. While infections were previously concentrated among men who have sex with men, heterosexual infections and infections among women are now also increasing.
| Item | Content |
|---|---|
| Increasing trend | Rapid increase since the 2010s. Over 10,000 cases reported annually in 2023 (record high) |
| Changes in infected demographic | Previously men who have sex with men → rapid increase in heterosexual and female infections |
| Age group | Primarily 20s-40s. Significant increase in young women |
| Congenital syphilis | Increase in reports of congenital syphilis in infants due to increased infection in pregnant women |
Routes of syphilis infection
- Sexual activity (most common): Can be infected through vaginal sex, anal sex, and oral sex
- Contact with mucous membranes or wounds: Direct contact with syphilis lesions (ulcers, rashes)
- Mother-to-child transmission (congenital syphilis): Infection from an infected mother to the fetus through the placenta
- Blood infection: Sharing needles, etc. (rare)
💡 Condoms offer some protection against syphilis, but are not completely effective, as infection can still occur through contact with uncovered areas (genitals, mouth area) where lesions may be present.
Symptoms of syphilis - by stage
| Stage | Timing | Main symptoms | Characteristics |
|---|---|---|---|
| Primary stage | 3-6 weeks after infection | A hard chancre appears at the infection site (genitals, mouth, anus, etc.) | Often overlooked because it is painless and disappears naturally |
| Secondary stage | 3-12 weeks after infection | Generalized rash (including palms and soles of feet), fever, swollen lymph nodes, oral ulcers | Symptoms are diverse and can be difficult to recognize as syphilis. This is the most infectious period. |
| Latent stage | After secondary stage - several years | No symptoms | Infection goes unnoticed without testing. Risk of transmitting to others exists. |
| Tertiary/Late stage | Several years later | Severe damage to the heart, aorta, brain, and nerves (neurosyphilis, cardiovascular syphilis) | If left untreated, it can be life-threatening. |
⚠️ "Symptoms disappeared" does not mean "cured." Syphilis symptoms disappear naturally, but the bacteria remain in the body. Infection can still occur even after symptoms disappear, and if left untreated, it will worsen. Be sure to get tested and treated.
Syphilis testing and treatment
| Item | Content |
|---|---|
| Testing method | Blood test (Treponema pallidum antibodies, RPR). Detectable 3-4 weeks after sexual activity. |
| Treatment method | Oral penicillin-based antibiotics (e.g., amoxicillin). Curable if in primary or secondary stage. |
| Treatment period | Primary to secondary stage: approximately 2-4 weeks. Late-stage requires longer treatment. |
| Our clinic's response | Online consultation, mail-in test kit, and prescription available. |
Syphilis prevention with DoxyPEP
Clinical trials have shown that taking DoxyPEP within 72 hours after condomless sexual activity can prevent syphilis infection by approximately 70-80%. It is the most established STD prevention medication for syphilis.
- Timing of administration: Once within 72 hours (3 days) after sexual activity
- Dosage: Doxycycline 200mg (2 tablets of 100mg)
- Target: Especially MSM (men who have sex with men) and transgender women. However, anyone who has engaged in risky sexual behavior should consult a doctor.
- Prevention effectiveness is maximized when combined with regular testing.
Frequently Asked Questions
Rashes on the palms and soles of the feet are one of the typical symptoms of secondary syphilis. If you have any concerns, get tested immediately. Syphilis rashes often don't itch, which can make them difficult to distinguish from drug eruptions or allergies.
No, you do not. Even if syphilis is completely cured with treatment, immunity does not remain, so re-infection is possible. Regular testing and prevention (using DoxyPEP, condoms) are necessary even after recovery.
Due to a prevention rate of approximately 70-80%, there is a 20-30% chance of infection occurring. It is important to undergo regular syphilis tests and seek early treatment if infected.
Related columns
What is DoxyPEP? A doctor explains the STD prevention medication to take within 72 hours after sexual activity What are the effects of DoxyPEP? Prevention rates and limitations for syphilis, chlamydia, and gonorrhea A prevention plan combining regular STD testing and DoxyPEPConsultation hours and access (online medical care)
| Clinic Name | Mona Aoyama Clinic |
| Consultation Type | Online consultation (nationwide) / In-person consultation (Tokyo, Aoyama) |
| Location | D Building 3F, 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) |
For syphilis testing and DoxyPEP prescription, contact Mona Aoyama Clinic.
Online medical care available nationwide. Supports mail-in testing and same-day prescriptions.