Overview
Syphilis is a bacterial infection passed on through sexual contact and from a pregnant woman to her baby. It moves through stages, and between them it causes no symptoms at all while continuing to damage the body.
It is entirely curable with antibiotics. The reason it still causes serious harm is that people do not know they have it. WHO estimates 8 million adults acquired syphilis in 2022, and that 1.1 million pregnant women were infected, resulting in over 390 000 adverse birth outcomes.
Disease Summary
- Category
- Infectious Disease
- Cause
- Treponema pallidum
- Transmission
- Sexual contact, and from mother to baby in pregnancy
- Body System
- Multiple organ systems
- Preventable
- Yes
- Curable
- Yes
Symptoms
Common Symptoms
Syphilis progresses in stages. Symptoms come and go, and their disappearance does not mean the infection has gone.
A Painless Sore
The first sign is usually a single firm, painless sore where the bacteria entered. Because it does not hurt, it is often missed, particularly inside the vagina, anus or mouth. CDC states sores usually last 3 to 6 weeks and heal whether or not treatment is given.
A Rash, Often on the Palms and Soles
In the second stage a rash appears, and a rash on the palms of the hands and soles of the feet is particularly suggestive of syphilis.
Fever and Feeling Unwell
Fever, sore throat and general malaise accompany the second-stage rash.
Swollen Lymph Glands
Swollen glands are common in the second stage.
Patches in the Mouth or on the Genitals
Moist raised patches can appear in warm moist areas. These are highly infectious.
Hair Loss in Patches
Patchy hair loss is a recognised feature of the second stage.
Muscle Aches and Tiredness
General aching and fatigue accompany the other second-stage symptoms.
Long Periods With No Symptoms at All
Between stages, syphilis causes nothing at all while remaining present. This silent phase can last years.
Danger Signs
Seek urgent medical attention immediately if any of the following symptoms develop.
Headache, Confusion or Personality Change
Syphilis can affect the brain at any stage, not only late in the illness, and this needs urgent assessment.
Changes in Vision
Syphilis affecting the eye can cause permanent loss of sight and is a medical emergency.
New Hearing Loss or Ringing in the Ears
Syphilis affecting hearing needs urgent treatment to prevent permanent loss.
Chest Pain or Breathlessness
Late syphilis can damage the heart and the main artery leaving it.
Any Positive Test in Pregnancy
This requires treatment without delay, because the baby can be protected only by treating the mother.
Diagnosis
Testing, Because Symptoms Are Unreliable
Syphilis is frequently symptom-free, and the sore of the first stage heals on its own whether treated or not. Only a blood test establishes whether the infection is present.
Antenatal Screening
WHO states that congenital syphilis can only be prevented by diagnosing and treating the mother, which makes testing in every pregnancy the central intervention.
Examination for Sores, Rash and Glands
A full examination including the genital, anal and oral areas, because the sore is painless and easily missed.
Staging the Infection
Working out which stage the infection has reached determines how long treatment needs to be.
Assessment for Nervous System, Eye and Ear Involvement
Where there are neurological, visual or hearing symptoms, further investigation is needed, because these change the treatment.
Laboratory Tests
Rapid Syphilis Test
Can be done at the clinic or in antenatal care without a laboratory. This is what makes same-day testing and treatment possible in pregnancy.
Screening Blood Test
Detects antibodies to the infection. A reactive result needs a second, different test to confirm it.
Confirmatory Blood Test
A second test of a different type confirms the diagnosis, because no single test is sufficient on its own.
Quantitative Antibody Test
Gives a number that is followed after treatment. A falling level shows the treatment has worked.
Examination of Spinal Fluid
Done where there are symptoms suggesting the brain or nerves are involved, because that changes the treatment.
Treatment
Penicillin Injection
The treatment for syphilis at every stage. It is inexpensive, highly effective and has been used for decades. CDC states syphilis is curable with the right antibiotics.
Treatment in Pregnancy
WHO states that congenital syphilis can only be prevented by diagnosing and treating the mother with penicillin. Treating early in pregnancy protects the baby.
Intravenous Treatment for Nervous System, Eye or Ear Involvement
Where syphilis has reached the brain, eye or ear, a longer intravenous course is needed rather than the standard injection.
Treating Sexual Partners
Partners are tested and treated, because otherwise reinfection is near certain.
Follow-Up Blood Tests
The quantitative antibody level is checked after treatment to confirm the infection has cleared.
Prevention
Use condoms consistently and correctly
WHO states this is the best way to prevent syphilis. Note that condoms do not cover every area where a sore can appear, so protection is good but not absolute.
Test in every pregnancy
This is the single most effective measure for preventing congenital syphilis, and it can be done with a rapid test at the first antenatal visit.
Test regularly if you are at ongoing risk
Because syphilis is frequently symptom-free, regular testing is the only way to find it early.
Tell partners so they can be tested
Partner notification protects them and prevents reinfection. Many clinics will help with this anonymously.
Complete treatment and attend follow-up
Follow-up blood tests confirm the infection has cleared. Treatment is not complete until that is established.
Know that past infection gives no protection
CDC states that reinfection is possible after treatment. Having had syphilis does not prevent getting it again.
Risk Factors
Pregnant Women and Their Babies
WHO estimates that 1.1 million pregnant women were infected in 2022.
- Women who do not receive antenatal testing
- Women who test positive but are not treated in time
- WHO reports over 390 000 adverse birth outcomes in 2022
- Treatment of the mother is the only way to protect the baby
People With Ongoing Sexual Risk
WHO and CDC both identify testing as the key intervention for these groups.
- People with new or multiple partners
- People whose partner has been diagnosed with syphilis or another sexually transmitted infection
- Men who have sex with men
- Sex workers and their clients
People Living With HIV
The two infections frequently occur together and each affects the other.
- Syphilis increases the chance of acquiring and transmitting HIV
- Syphilis can progress faster in people with untreated HIV
- Both are tested for together as standard practice
- Regular testing is recommended for people on HIV treatment
Complications
Congenital Syphilis
Passed to the baby in pregnancy, it causes stillbirth, newborn death, low birth weight, bone and organ damage, deafness and blindness.
Damage to the Brain and Nerves
Syphilis can reach the nervous system at any stage, causing headache, confusion, personality change, stroke and eventually dementia.
Loss of Vision
Syphilis affecting the eye can cause permanent blindness and is treated as an emergency.
Hearing Loss
Syphilis affecting the inner ear can cause permanent deafness if not treated promptly.
Damage to the Heart and Main Artery
Late syphilis can weaken the wall of the main artery leaving the heart, which can be life threatening.
Increased HIV Risk
The sores of early syphilis make both acquiring and transmitting HIV considerably more likely.
When to Seek Medical Care
Any Sore, Ulcer or Rash in the Genital, Anal or Oral Area
Even a painless one. Especially a painless one, since that is what syphilis causes.
A Rash on the Palms or Soles
This pattern is particularly suggestive of syphilis and should always be tested.
At the First Antenatal Visit
Syphilis testing in pregnancy is what prevents congenital syphilis, and treatment is simple and safe.
Headache, Vision Change, Hearing Loss or Confusion
In anyone who may have syphilis, these need urgent assessment, because they indicate the infection has reached the nervous system, eye or ear.
If a Sexual Partner Has Been Diagnosed
Go for testing even if you feel entirely well, because syphilis is frequently symptom-free.
Prognosis
Syphilis Is Curable
CDC states that syphilis is curable with the right antibiotics. Early infection is cured with a single injection.
Damage Already Done May Be Permanent
CDC states that treatment does not repair damage the infection has already caused, which is why early diagnosis matters.
Treating the Mother Protects the Baby
Treatment early in pregnancy prevents congenital syphilis, which is otherwise a frequent cause of stillbirth and newborn death.
Follow-Up Confirms the Cure
Blood tests over the following 6 to 12 months confirm that the infection has cleared.
Differential Diagnosis
Herpes
Causes genital ulcers, but these are usually painful and recur in crops, unlike the single painless sore of early syphilis.
Chancroid and Other Causes of Genital Ulcers
Produce painful ulcers, and are separated by specific testing.
Mpox
Causes genital and mouth lesions that can look identical, and WHO advises testing for syphilis alongside when mpox is suspected.
Other Causes of a Widespread Rash
Drug reactions and several viral illnesses produce similar rashes, but rarely on the palms and soles.
Other Sexually Transmitted Infections
Gonorrhoea, chlamydia and HIV often occur alongside syphilis, which is why a full screen is usually offered.
References
World Health Organization: Syphilis
WHO fact sheet on transmission, stages, congenital syphilis, testing and treatment.
CDC: About Syphilis
Stages of syphilis, symptoms, testing, treatment and complications.
CDC: About Congenital Syphilis
How syphilis passes to a baby, what it causes and how antenatal treatment prevents it.
World Health Organization: Sexually transmitted infections
Global estimates for syphilis and the other curable sexually transmitted infections.
Frequently Asked Questions
Can syphilis be cured?
Yes. CDC states that syphilis is curable with the right antibiotics. Early infection is cured with a single penicillin injection. Treatment does not repair damage the infection has already caused, which is why testing early matters.
Can I have syphilis without symptoms?
Yes, and this is common. The first sore is painless and heals on its own whether treated or not. Between stages the infection causes no symptoms at all, sometimes for years, while remaining present. Only a blood test can tell you.
Why is syphilis tested for in pregnancy?
Because it can be passed to the baby, causing stillbirth, newborn death, deafness, blindness and other serious harm. WHO states that congenital syphilis can only be prevented by diagnosing and treating the mother. A rapid test at the first antenatal visit makes same-day treatment possible.
If I was treated before, am I protected?
No. CDC states that reinfection is possible after treatment. Having had syphilis gives no immunity, so anyone with ongoing risk should keep testing regularly.
Do condoms prevent syphilis?
They greatly reduce the risk. WHO states that using condoms consistently and correctly is the best way to prevent syphilis. They are not complete protection, because sores can appear in areas a condom does not cover.