Short answer
Syphilis is a bacterial STI that progresses in stages. And each stage has its own signs, tests, and treatment shape.
It is diagnosable with blood tests and treatable with clinician-directed antibiotics. But stages, pregnancy, and follow-up make professional care essential from the first sore onward.
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See Tests & Prices →Transmission that respects no orifice
Syphilis spreads through direct contact with an infectious sore during vaginal, anal, or oral sex.
It can pass during pregnancy with severe consequences for the baby, which is why pregnancy screening is routine rather than optional.
Route details are covered in How Syphilis Is Transmitted.
Stages and symptoms, and why staging matters
Primary: a painless sore that heals spontaneously (healing proves nothing. Infection continues).
Secondary: rash often including palms and soles, mucous patches, hair loss.
Latent: no symptoms but detectable by blood test and still consequential.
Tertiary: severe organ damage years later.
Stages guide how treatment is structured and how follow-up is scheduled. Which is why clinicians stage before treating rather than treating generically.
Testing and diagnosis as a system
Diagnosis combines treponemal and non-treponemal blood tests, each answering a different question (exposure history versus current activity).
Sores can also be tested directly.
Because other conditions mimic syphilis at every stage, clinician interpretation matters more here than for most STIs.
The two-test logic is explained in Syphilis Testing: Blood Tests Explained.
Treatment and follow-up principles
Stage-matched antibiotic therapy prescribed and monitored by clinicians, with scheduled follow-up blood tests confirming response over months, partner evaluation by stage-specific look-back windows, and retesting advice.
Pregnancy, neurologic symptoms, or HIV coinfection intensify the protocol toward specialty care.
No stage is managed at home; every stage is manageable in care.
When to seek care
Seek prompt care for any genital sore or unexplained rash, after possible exposure, or immediately if pregnant and at risk. Congenital syphilis is preventable with timely treatment.