Reviewed & updated August 23, 2026

Is Syphilis an STD? Stages, Symptoms & the Comeback

Quick answer

Yes — syphilis is one of the oldest recognized STDs, caused by the bacterium Treponema pallidum. It spreads through direct contact with syphilitic sores during vaginal, anal or oral sex. Cases hit a 70-year US high recently, and it cures completely with penicillin — but only if caught: untreated, it marches through stages toward neurological and cardiac damage years later.

The four-act play of untreated syphilis

StageTimingWhat happens
Primary~10–90 days post-exposureOne firm painless ulcer (chancre) at contact site; heals itself in 3–6 weeks — infection continues silently
SecondaryWeeks–months laterRough red-brown rash famously on palms/soles, fever, swollen nodes, malaise; also resolves alone
LatentYearsZero symptoms; blood tests positive; still transmissible early-latent
Tertiary10–30+ yearsNeurosyphilis (dementia, vision loss), cardiac damage, gummas — largely irreversible

The self-healing sores are syphilis's genius: victims believe themselves cured precisely as the bacterium spreads system-wide.

209K+US cases all stages 2023 — highest rate since 1950
3,882congenital syphilis cases 2023 — a national emergency designation
1 shotBicillin L-A penicillin cures primary/secondary stages

How it spreads (and doesn't)

Testing & the one-shot cure

Blood serology catches every stage: screening RPR plus confirmatory treponemal tests. Detection begins ~3 weeks after exposure (up to 90 days worst case) — window timing matters (chart here). Anyone with unexplained palm rash, painless genital sore, or a partner diagnosed should test immediately.

The cure remains gloriously old-school: benzathine penicillin G intramuscular injection — single dose for primary/secondary; three weekly doses for late latent. Penicillin-allergic patients get doxycycline courses instead (details). Follow-up titers confirm cure over months (reading titers).

Jarisch-Herxheimer note: treatment sometimes triggers a day of fever/aches as bacteria die en masse — dramatic but harmless and self-resolving.

Neurological symptoms (vision/hearing changes, headaches) demand urgent evaluation for neurosyphilis regardless of stage. Related guides: the historical VD umbrella, rash identification.

Frequently asked questions

Is syphilis an STD?
Yes — a classic bacterial sexually transmitted disease, currently resurging to levels unseen since the 1950s.
Is syphilis curable?
Completely, at any stage — though tertiary organ damage may be permanent, further progression halts with penicillin.
What does a syphilis sore look like?
A single firm, round, painless ulcer with clean edges — easy to ignore precisely because it doesn't hurt (visual guide).
Can you get syphilis from kissing?
Yes, when mouth sores are present — documented transmission route.
Why is congenital syphilis surging?
Untreated maternal infections + declining prenatal care access. Every pregnancy needs first-trimester screening; high-risk areas repeat it in the third.

Sources & further reading