Syphilis: symptoms and treatment
Syphilis is a sexually transmitted infection caused by bacteria, and it matters because, left untreated, it can progress through several stages and cause serious damage to the heart, brain, and nervous system. The good news is that syphilis is curable with antibiotics, especially when found and treated in its early stage. This page explains it fully — the cause and how it spreads, the four stages of symptoms, complications, transmission from mother to child, diagnosis, treatment, and prevention — so you can understand and look after your sexual health with confidence.
What syphilis is
Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum.
Curable, but not to be ignored
Syphilis is curable with antibiotics, but if left untreated, the bacteria stay in the body and gradually spread, which can cause serious long-term damage.
Knowing helps you take care
Understanding the symptoms and stages of syphilis helps you find and treat it early. See the overview of STIs at sexually transmitted infections (STIs).
Common and can recur
Syphilis is a common infection and has been rising in many places, and it is worth knowing that having had it and been cured does not give lasting immunity, so you can be reinfected if exposed again, which is why prevention and regular testing still matter.
Cause and transmission
Syphilis passes from person to person in two main ways.
How it spreads
- through sex — direct contact with a sore or the fluids of an infected person during vaginal, anal, or oral sex
- from mother to child — during pregnancy or birth, which is called congenital syphilis
Behaviours that raise the risk
Having sex without condoms, having several partners, and contact with an infected person's sores all raise the chance of infection. The bacteria enter easily through mucous membranes or broken skin.
The four stages of syphilis
The symptoms of syphilis fall into four stages, which may follow in order or overlap.
An overview of the four stages
| Stage | Timing | Main signs |
|---|---|---|
| Primary | About 3 weeks after infection | A painless firm sore |
| Secondary | About 3 to 12 weeks | A body-wide rash, including palms and soles, and flu-like symptoms |
| Latent | Months to years | No symptoms, but the infection remains |
| Tertiary | Years later | Damage to the heart, brain, and nerves |
You may not know you are infected
Because the early sore is painless and heals on its own, and the latent stage has no symptoms, many people do not know they are infected and may pass it on unknowingly. This is why testing matters so much.
The primary and secondary stages in detail
The first two stages are when symptoms are usually visible.
Primary stage: the firm sore
About 3 weeks after infection, a firm sore (chancre) appears — a small sore with a raised firm edge that is painless, usually on the genitals, mouth, or anus. It heals on its own in 3 to 8 weeks, but the bacteria remain in the body.
Secondary stage: a body-wide rash
About 3 to 12 weeks after infection, the bacteria spread through the body, causing a rash that is not itchy or painful, which can appear on the palms and soles, along with flu-like symptoms such as fever, swollen lymph nodes, sore throat, and hair loss. These ease on their own and move into the latent stage.
Symptoms are similar in men and women
The symptoms are broadly similar in both sexes, differing in where the lesions appear. In women, a sore may be in a place that is hard to see, such as the cervix, so the early stage can be missed.
The latent and tertiary stages
If untreated, syphilis moves into a stage with no symptoms and then its most severe stage.
Latent stage
This stage has almost no symptoms, but the bacteria remain in the body and can still be passed to others early on, including from mother to child. This stage can last for years.
Tertiary stage
Seen in a proportion of those who go untreated, this is the final and most severe stage, where the bacteria permanently damage important organs, such as the brain and nervous system, the heart and blood vessels, the liver, and the bones, which can become life-threatening. Treating it early prevents this stage.
Complications
If left until the severe stage, syphilis can cause serious complications.
Effects on body systems
- the nervous system (neurosyphilis) can cause dementia, movement problems, paralysis, seizures, or loss of sight and hearing
- the heart and blood vessels can develop a leaking heart valve or an aneurysm
- the bones and internal organs can be damaged
Preventable with early treatment
These complications happen in the late, untreated stage, and finding and treating syphilis early prevents almost all of this damage.
Why it is called a great imitator
Syphilis is sometimes called a great imitator because its symptoms can resemble many other conditions, such as a rash that looks like a common skin problem, so a blood test confirms it more clearly than looking at symptoms alone.
Syphilis and pregnancy
Syphilis in pregnancy matters because the infection can pass to the baby.
Congenital syphilis
If an infected mother is not treated, the bacteria can pass to the baby in the womb, causing serious complications such as premature birth or health problems for the baby.
Screening in antenatal care
The good news is that screening for syphilis during antenatal care and treating an infected mother prevents transmission to the baby effectively, so every pregnant woman should be tested. Read about pregnancy care at HIV and pregnancy and having children.
Diagnosis
Diagnosing syphilis is straightforward.
How it is tested
- a blood test is the most common and accurate method, looking for antibodies to the bacteria
- a test from a sore takes a sample from a lesion to examine under a microscope, for those with a visible sore
- a spinal fluid test in cases where the bacteria are suspected of spreading to the nervous system
Testing leads to treatment
Because syphilis may have no symptoms, a blood test is an important way to know your status and start treatment in time. Read about testing at STI testing.
Treatment
The best news is that syphilis is curable with antibiotics.
Penicillin is the mainstay
The main treatment is a penicillin injection, which works well to clear the bacteria. The number of doses depends on the stage — the early stage is often a single injection, while later stages may need injections over several weeks. For those allergic to penicillin, a doctor may use another antibiotic instead.
Follow-up and things to know
After treatment, a doctor arranges follow-up blood tests to confirm it has worked. Some people have temporary symptoms after the injection, such as fever or aches, which pass on their own. You should avoid sex until treatment is complete and a doctor confirms it is safe, and a partner should be tested and treated too.
The earlier, the simpler
Treatment in the early stage is usually simpler and uses less medicine than in later stages, so not letting the infection go on for long is better for both treatment and preventing complications, and if you suspect infection, see a doctor promptly.
Prevention
There is currently no vaccine for syphilis, so prevention focuses on reducing risk and testing.
How to prevent it
- use condoms every time you have sex — vaginal, anal, and oral. Read more at condoms
- have regular STI screening, especially with a new partner
- tell a partner and care together if you are diagnosed
- pregnant women should be screened during antenatal care
Combination prevention
Using several methods together gives the best protection, and regular testing helps find and treat it early if you do get infected.
Test even without symptoms
Because syphilis can have no symptoms for a long time, testing at suitable intervals even when you feel well is good self-care, especially for those with new partners or a risk.
Syphilis and HIV
Syphilis and HIV are connected in ways worth knowing.
Syphilis sores increase HIV risk
The firm sore and lesions of syphilis make it easier for HIV to enter the body, so a person with syphilis has a higher risk of getting HIV.
Test for both together
Testing for syphilis and HIV together is a good approach, and using condoms protects against both. People at risk of HIV may also consider PrEP. See the overview at sexually transmitted infections (STIs).
In summary
Syphilis is a bacterial sexually transmitted infection that runs through four stages — starting with a painless firm sore, followed by a body-wide rash, a latent stage with no symptoms, and a final stage that can damage the heart, brain, and nerves. Because many stages have no clear symptoms, a blood test is an important way to know your status.
The good news is that syphilis is curable with penicillin, especially when treated in its early stage. Prevention is possible through condoms, regular testing, and screening in pregnancy, even though there is no vaccine.
If you want to test for syphilis, other STIs, or HIV, find and book a clinic at Love2Test.
References
Based on guidance from international and national health authorities.