Syphilis has an incubation period of about 10 to 90 days, averaging around three weeks, between exposure and the first painless sore (chancre) of primary syphilis CDC, About Syphilis. After that sore heals on its own, secondary symptoms typically appear weeks to a few months later, followed by a symptom-free latent phase that can last years.
~3 wks; 10–90 days
by stage
| Item | Value |
|---|---|
| Primary sore | painless — ~3 wks; 10–90 days |
| Testing | 2 blood tests |
| Treatment | penicillin — by stage |
| Symptoms fade | ≠ cured |
The essentials: how syphilis moves stage by stage
Syphilis is caused by the bacterium Treponema pallidum, a corkscrew-shaped organism that enters through tiny breaks in skin or mucous membranes during sex. Once inside, it multiplies locally and then spreads through the bloodstream, so a disease that starts as a single sore can later affect the skin, organs, brain, and nervous system. The right antibiotics cure it. People get tripped up by the timing, because each stage runs on its own clock.
Syphilis is so often missed because of its incubation pattern. The first sore is painless, and it heals whether or not you treat it. That feels like recovery, but the bacteria have simply moved inward. The CDC puts it bluntly: symptoms going away does not mean you're cured. Without treatment the infection marches on to the latent and possibly tertiary stages.
- Incubation to primary: roughly 10 to 90 days after exposure (about 3 weeks on average), a chancre appears.
- Primary stage: the chancre lasts 3 to 6 weeks and heals with or without treatment.
- Secondary stage: a rash and body-wide symptoms appear weeks to months after the sore, and also resolve on their own.
- Latent stage: no symptoms at all, sometimes for years, while blood tests stay positive.
- Tertiary stage: in untreated cases, 10 to 30 years later, though serious damage can come sooner StatPearls.
Syphilis can invade the eyes (ocular syphilis) or the nervous system (neurosyphilis) at any stage, not just decades in. New vision changes, severe headache, or neurological symptoms in someone with syphilis are an emergency. Don't wait them out.
Symptoms by stage and when they show up
Primary syphilis
Primary syphilis announces itself with one or more sores at the exact spot the bacteria entered: the penis, vagina, anus, rectum, lips, or mouth. The classic chancre is painless, firm, and round, which is why it's easy to ignore. A sore on the cervix, inside the rectum, or at the back of the throat may never be noticed. It lasts 3 to 6 weeks and heals on its own, so many people assume whatever it was has passed.
Secondary syphilis
Weeks to months after the chancre, the bacteria are circulating in the blood and produce the hallmark secondary rash: a rough, red or reddish-brown eruption that can show up on the palms and soles, a pattern few other rashes share. Alongside it people may have mucous-membrane lesions, fever, swollen lymph nodes, sore throat, patchy hair loss, headache, weight loss, muscle aches, and fatigue. These symptoms also fade without treatment, reinforcing the false sense of recovery.
Latent and tertiary syphilis
Latent syphilis is the silent phase: no symptoms, but the infection persists and remains detectable by blood test. Clinicians split it into early latent (acquired within the past 12 months) and late latent or unknown duration (more than a year, or no clear timeline). That split sets the treatment schedule CDC, latent syphilis. Left untreated for years, syphilis can reach the tertiary stage and damage the heart, blood vessels (cardiovascular syphilis), brain, and nervous system, with manifestations that can be disabling or fatal.
Testing: when a test will actually catch it
Diagnosis is a simple blood draw, but it requires two tests: a nontreponemal test (RPR or VDRL) and a treponemal test (TP-PA, FTA-ABS, EIA, or CIA). The two can be run in either order. The traditional algorithm screens nontreponemal first then confirms with treponemal, while the reverse-sequence algorithm starts treponemal and confirms with a quantitative nontreponemal titer. Both are acceptable CDC Lab Recs, 2024.
Timing matters. Antibodies take time to build, so a test drawn during the earliest primary infection can be negative even though you're infected. The CDC notes antibodies may take up to two weeks after the chancre appears, and the chancre itself shows up about three weeks after exposure. If you test soon after a risky encounter and it's negative, retest before you trust it. For how the timing breaks down across different infections, see our guide on when to test after exposure, and you can get tested when the window is right. The full breakdown of which assays do what lives on our syphilis test page.
Treatment: penicillin, dosed by stage
Penicillin G, given by injection, is the preferred drug for every stage of syphilis, and there is no oral medication that dependably substitutes CDC, P&S syphilis. The dose follows the stage. Primary, secondary, and early latent syphilis are treated with a single intramuscular injection of benzathine penicillin G. Late latent, unknown-duration, and tertiary syphilis require three weekly injections. Neurosyphilis, ocular, and otosyphilis are treated more aggressively with intravenous penicillin over a stretch of days CDC, neurosyphilis.
The right product for early syphilis is benzathine penicillin G (Bicillin L-A). The combination product Bicillin C-R is not an acceptable substitute and has caused real treatment-failure errors. For penicillin-allergic, non-pregnant patients, doxycycline is the standard alternative, though the course is longer for late latent disease, and azithromycin is not recommended because of resistance. The full regimens and durations are on our syphilis treatment page.
Two things about the shot catch people off guard. Within the first 24 hours many develop fever, chills, and headache, the Jarisch-Herxheimer reaction. It's dying bacteria releasing inflammatory signals, not a penicillin allergy; it affects roughly 95% of people treated for secondary syphilis and settles within about a day StatPearls, JHR. Cure is confirmed by blood titers, not by feeling better: a fourfold drop in the nontreponemal titer (say 1:32 to 1:8) over 6 to 24 months means it worked, while a fourfold rise signals reinfection or failure. Follow-up titers at 6 and 12 months (and 24 months for latent disease) are part of the cure.
In pregnancy the stakes are highest. Untreated syphilis harms the baby in 50 to 80% of cases through stillbirth, prematurity, newborn death, or congenital infection, and there is no safe alternative to penicillin. Most reported penicillin allergy is mislabeled, over 90% of people who think they're allergic aren't, so an allergic pregnant patient is desensitized and treated with penicillin anyway, since it's the only drug that protects the fetus CDC, syphilis Tx.
Prevention while syphilis is climbing
Syphilis is rising sharply. There were about 53,000 primary-and-secondary cases reported in 2023, and the late/unknown-duration stage nearly doubled per capita between 2020 and 2023 CDC AtlasPlus, 2023. Congenital syphilis rose 77% in four years to its highest level in decades. Rates aren't even. In 2023, South Dakota, Washington DC, New Mexico, and Mississippi ran several times the national average. Having syphilis also roughly doubles the risk of acquiring HIV.
Core prevention is unglamorous and effective: correct and consistent condom use, mutual monogamy with a partner who has tested negative, and routine screening for those at risk. Condoms reduce but don't eliminate risk, since a sore outside the covered area can still transmit, and that includes oral exposure, which we cover in can you get syphilis from oral sex?. For people at higher risk, DoxyPEP — 200 mg of doxycycline within 72 hours after sex — reduced syphilis acquisition by about 73% and is recommended through shared decision-making for men who have sex with men and transgender women who've had a bacterial STI in the past year CDC DoxyPEP, 2024.
When to see a clinician
- You notice a painless sore on the genitals, anus, or mouth — even if it's healing or gone, get a blood test.
- A rough rash appears on your palms, soles, or body, with or without fever and swollen glands.
- You had a possible exposure; don't rely on an early negative — ask about retesting timing.
- You're pregnant; syphilis screening is part of standard prenatal care and treatment prevents congenital infection.
- You have new vision changes, severe headache, or neurological symptoms with known or suspected syphilis — this is an emergency.