Syphilis is caused by Treponema pallidum. It usually enters through small breaks in skin or mucosa during sexual contact, and it can also pass by blood or across the placenta in pregnancy.
An ulcer may be painless, and a rash may fade on its own. Fading symptoms do not mean the infection is gone. Blood tests and a clinician’s staging should come before treatment.
Key points: Syphilis can spread by sexual contact, blood and from a pregnant person to the fetus. Primary disease is often a painless ulcer. Secondary disease may add a rash and flu-like symptoms. Later disease can involve nerves, eyes or the heart and vessels. Penicillin-class medicine is common, but the course depends on the stage. Blood tests continue after treatment, and partners are assessed by timing of contact.
How does syphilis spread?
Spread is more likely when an ulcer, a moist flat lesion or infected secretions are present on skin or mucosa. Direct contact at the penis, vulva, vagina, anus or mouth can let the organism through a tiny break. Semen, blood and vaginal fluid can also transmit it if they meet a break in the skin.
Transfusion and shared needles are less common routes that still matter. Screening of donated blood has lowered transfusion risk. Sharing injection equipment remains a route.
Without diagnosis and treatment in pregnancy, the organism can cross the placenta and cause congenital syphilis. Severe outcomes can include pregnancy loss, stillbirth, or problems of the skin, bones, liver, blood or nerves in a newborn. Risk depends on timing and treatment. Not every pregnancy reaches a severe outcome.
A syphilis test does not replace other checks. After condomless contact, discharge or an ulcer, these topics can be discussed together: HPV vaccine, HIV prevention medicine, genital warts
What symptoms can each stage show?
People of any sex can pass through similar stages. An ulcer inside the vagina, cervix or anus is easy to miss. The time ranges are approximate and should not be used to self-stage.
Primary
About 10 to 90 days after contact, one or more painless ulcers, sometimes called a chancre, may appear at the entry site. Nearby lymph nodes may swell. The ulcer often heals over several weeks while the organism can remain.
Secondary
About 6 to 8 weeks after the ulcer, some people develop a rash on the trunk, palms or soles that does not itch or hurt. Moist flat lesions can appear around the genitals. Fever, fatigue, sore throat or hair loss may occur. These signs can fade after several weeks without medicine, which does not mean the infection has passed.
Latent and late
In latency, blood tests may stay positive while no lesion is visible. Years later, some untreated people develop problems of the nerves, eyes, ears or blood vessels, including headache, hearing or vision change, stroke-like symptoms, or aortic disease. Not everyone who is untreated reaches this stage, and the absence of symptoms does not rule it out.
At any stage, an untreated pregnant person can pass the infection to the fetus. Prenatal blood testing should include syphilis, and any new risk contact during pregnancy should be told to the obstetric clinician.
| Stage | Approximate timing | Clues people notice |
|---|---|---|
| Primary | About 10–90 days after contact | Painless ulcer and local lymph-node swelling |
| Secondary | Several weeks after the ulcer | Rash on palms, soles or trunk, and flu-like symptoms |
| Latent | After symptoms fade | No visible lesion; blood tests may stay positive |
| Late | Years later in some people | Nerve, eye, ear or cardiovascular problems |
Which tests are used?
Clinicians usually ask about timing, ulcers and rash, then draw blood. A positive screening test needs a second, syphilis-specific test, because other conditions can raise the first number. One value cannot stage the infection or show whether it is currently contagious.
If an ulcer is still present, some clinics sample it for the organism. A negative sample does not by itself rule syphilis out. Headache, vision or hearing change, or unsteady walking may lead to a neurologic review and, in selected cases, a spinal-fluid test. That is not routine for every rash.
How are treatment and follow-up arranged?
Early syphilis is often treated with injected penicillin-class antibiotic. The number of doses, and whether a longer course is needed, depends on early, late or neurologic disease and on pregnancy. People with penicillin allergy should not buy a substitute themselves.
Within hours of an injection, some people develop fever, headache or muscle aches. This reaction often settles. Trouble breathing, a rapidly spreading rash or severe symptoms need urgent care.
Fading symptoms do not mean follow-up can stop. Blood tests are repeated to see whether the titer falls. The pace differs. A plateau may lead to review for retreatment or a new infection.
When sex can resume depends on healing, blood tests and whether partners have been treated. A common discussion after early treatment is to wait about two weeks, but the instruction given at that visit is the one to follow.
Whether a partner needs treatment depends on how recent the contact was, the stage at that time, and the partner’s own blood test. Tell the clinician who may have been exposed. Do not share leftover medicine.
How can the chance of infection be lowered?
Fewer overlapping partners and a condom throughout sex reduce some direct contact. An ulcer on skin outside the condom can still transmit infection. If lubricant is needed, use a water-based product. Oil-based products such as baby oil or petroleum jelly can break latex condoms.
If infection is suspected, do not buy antibiotics at a pharmacy or use unverified remedies. The wrong dose can fade symptoms and make later blood tests harder to read.
People planning pregnancy, or already pregnant, should have syphilis blood tests in prenatal care. A new risk contact or a positive result during pregnancy should be taken to obstetric and infection care promptly.
Yes. Primary ulcers and secondary rashes can fade while the organism remains. Contact history and blood tests are required.
Infectiousness usually falls after suitable early treatment, but lesions should heal, follow-up should continue, and partners may still need care. Condomless contact afterward can cause a new infection.
Yes. The allergy history must be told to the clinician. Some people receive another antibiotic with closer follow-up. In pregnancy, desensitization under monitoring is sometimes used. Do not choose a substitute alone.
A positive test does not prove the fetus is already affected, but delay raises the chance of congenital infection, pregnancy loss or stillbirth. Obstetrics and related clinicians should arrange treatment and follow-up promptly.
A painless ulcer on the genitals or mouth, a rash on the palms or soles, sudden vision or hearing change, severe headache, unsteady walking, or possible infection in pregnancy should be assessed promptly. Do not start with pharmacy antibiotics.
Suggestions from the urologist
- A painless ulcer, a palm or sole rash, or unexplained lymph-node swelling needs blood tests and a history, not a photo alone.
- Penicillin-class antibiotics are common, but dose, number of injections and substitutes depend on stage, allergy and pregnancy.
- Fading symptoms do not show that the organism has left. Blood tests continue, and exposed partners need their own assessment.
- Pregnancy, neurologic symptoms, vision change or chest symptoms should not wait for a later stage.
Syphilis can be treated early, but the regimen, follow-up and partner checks belong in clinic. A clinician should see the tests and the contact history before any antibiotic is chosen.
