Syphilis is caused by a bacteria, and on the rise in recent years. Learn more about this common STI.
Syphilis is a common sexually transmitted infection (STI), with 190,242 total cases reported in 2024. It’s caused by the bacterium Treponema pallidum, which can be passed from one person with a syphilis infection to their partner(s) through sexual contact such as vaginal, anal, or oral sex. It is not passed along through casual contact such as hugging or a shared toilet seat. Many people have syphilis without knowing, so getting routinely tested if you’re sexually active is key.
Syphilis can cause sores, called chancres, on the genitals or sometimes the lips and mouth. It’s spread when your vulva, vagina, penis, anus, or mouth come into contact with these sores. Sores can be small, go unnoticed, or be mistaken for things like ingrown hairs or pimples, so many people with syphilis don’t know they have it and can spread it unknowingly. Importantly, the bacteria from syphilis are not shared through casual contact such as hugging, kissing, holding hands, coughing, or sitting on the toilet.
Syphilis can also be passed from a pregnant person to their baby if the infection is present during pregnancy, called congenital syphilis. Congenital syphilis is on the rise, so it’s important to get tested for syphilis during pregnancy for timely treatment to be given if needed.
The most common symptoms of many STIs, including syphilis, are no symptoms at all. Some estimate that up to 50% of people with syphilis are asymptomatic (or don’t show symptoms) for syphilis. This is what makes routine STI testing so important!
There are several stages of syphilis, and symptoms can vary between stages.
Primary Stage Syphilis:
Secondary Stage Syphilis:
Latent Stage Syphilis:
Tertiary Stage Syphilis:
Without treatment, syphilis can spread to other parts of the body and cause things like neurosyphilis, ocular syphilis, or otosyphilis. Neurosyphilis affects the brain and nervous system and can cause headaches, muscle weakness, coordination problems, and changes to your mental capabilities. Ocular syphilis affects the eyes and can cause eye pain, redness, changes to your vision, or in more extreme cases, blindness. Otosyphilis impacts the ears and can cause hearing loss, ringing or buzzing in the ears, or dizziness and vertigo.
Syphilis is readily treatable with antibiotics. It’s important to follow the instructions given by your healthcare provider and to take the full course of treatment, otherwise it’s possible for the infection to remain or return.
It’s helpful to share your diagnosis with any sexual partner(s) so that they can also get treatment and avoid spreading the infection to others, or back-and-forth between yourself and your partner(s).
While symptoms may not appear or be mild, getting treatment is still incredibly important, as the infection can develop serious and long-term side effects if left untreated.
The only way to completely avoid STIs like syphilis is to avoid sexual contact. However, sex is a normal and healthy part of many people’s lives and there are steps you can take to lower your risk. Here are some ways to have safer sex:
A well-known antibiotic can help prevent infection, too! Doxycycline, also simply called doxy, is proving to be an effective preventative treatment when used correctly. If taken within 72 hours after sexual contact, doxy can help prevent syphilis from becoming established in the body. This usage is called “doxy PEP.” So far, it’s only been proven to help in cisgender men and transgender women, but more studies are ongoing.
Please note that NCSD is not a medical facility. Content here is for informational purposes only and should not replace medical advice. Consult with a health care provider if you have questions or concerns regarding an STI.