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Bacterial STI Curable

Syphilis testing

Syphilis is a bacterial infection that moves through stages — a painless sore, a distinctive rash, years of silence, and then, in untreated cases, irreversible damage to the heart, brain and eyes. A blood test detects it. Penicillin cures it. But treatment can only halt the disease, not undo what it has already done — so catching it early is what actually matters. With 209,253 U.S. cases in 2023, including 3,882 in newborns, syphilis is not rare and it is not inevitable. Get tested below.

2023 U.S. rate (P&S)
15.8
per 100,000 — primary & secondary syphilis
Total cases (2023)
209,253
all stages combined
Congenital cases (2023)
3,882
newborn syphilis — a ten-year high
Curable
Yes
penicillin — but late damage is permanent

Where to get tested

Find syphilis testing near you

Choose your test and enter your city — we'll take you straight to local syphilis testing: nearby clinics and labs, prices, hours and county rates.

Test from home

At-home STD testing in the U.S.

if you'd rather skip the trip, an at-home kit ships to the U.S., you collect the sample privately, and mail it back to a CLIA-certified lab. Results come online in days, with a clinician available if anything is positive. Same labs as a clinic, no waiting room — and you can read how accurate at-home STD tests are before you order.

Want a free option first? The CDC-supported TakeMeHome program mails free at-home HIV self-test kits — and, in many areas, free STI kits — to your door, with no insurance or payment needed. The paid kits below add broader panels and faster turnaround.

  • Best range — couples & full panels

    myLAB Box

    $79 & up

    Screens for:
    Up to 14 infections — incl. HIV, syphilis, chlamydia, gonorrhea, hepatitis & herpes
    Sample:
    Self-collect: swab, urine, finger-prick
    Results:
    2–5 days, online
    • Free phone consult if positive
    • CLIA-certified labs
    • Couples & subscription options
    • Discreet packaging
    Order online myLAB Box review

  • Best for simplicity & support

    LetsGetChecked

    $89 & up

    Screens for:
    5–6 common STIs incl. chlamydia, gonorrhea, HIV, syphilis & trichomoniasis
    Sample:
    Finger-prick + urine/swab
    Results:
    2–5 days, online
    • 24/7 nurse support
    • Prescription for positives
    • CLIA-certified labs
    • Free shipping both ways
    Order online LetsGetChecked review

  • Best value — single tests

    Everlywell

    $49 & up

    Screens for:
    Chlamydia & gonorrhea, up to a 6-test panel adding HIV, syphilis, trichomoniasis & hep C
    Sample:
    Finger-prick + swab
    Results:
    Days, online
    • Telehealth visit if positive
    • CLIA-certified labs
    • HSA/FSA eligible
    • Subscription savings
    Order online Everlywell review

Every kit uses CLIA-certified labs. At-home testing is for screening; a reactive result should be confirmed and treated by a clinician. Prices and panels shown are illustrative and change often — confirm current details on the provider's site.

Understanding syphilis

What is syphilis?

Syphilis is caused by the spirochete bacterium Treponema pallidum — historically called the "great imitator" because it can mimic almost any other illness. It progresses in defined stages: a painless genital sore (primary), a body-wide rash and flu-like illness (secondary), a silent latent phase that can last decades, and — in about 25–30% of untreated people — destructive tertiary disease affecting the heart, aorta, brain and bones. Neurosyphilis and ocular syphilis can strike at any stage.

After falling to near-eradication in the early 2000s, syphilis has surged. Primary and secondary syphilis reached 57,169 cases and a rate of 15.8 per 100,000 in 2023 — the most infectious stages, when transmission is virtually guaranteed by sexual contact with a sore. Even more alarming is the rise in congenital syphilis: 3,882 newborns were infected in 2023, contributing to 279 stillbirths and infant deaths that a single prenatal blood test and a penicillin injection could have prevented. Because the first sore is painless and often hidden inside the vagina, rectum or throat, and the infection then vanishes into a silent latent phase, most people who have syphilis do not know it. A blood test is the only reliable way to find out.

Screening guidance

Who should get tested for syphilis?

Because syphilis is usually silent, the CDC and U.S. Preventive Services Task Force recommend routine screening for the groups most likely to have it — not just people with symptoms.

  1. 1

    Gay and bisexual men (MSM)

    MSM account for roughly 36–47% of all P&S syphilis cases. The CDC recommends testing at minimum once a year and every 3–6 months with new or multiple partners, active drug use, or HIV-positive status. Syphilis rates among MSM are more than 100 times the rate in heterosexual men.

  2. 2

    Everyone who is pregnant

    Screen at the first prenatal visit — period. Retest at 28 weeks and again at delivery in high-prevalence areas or with any ongoing risk. Untreated maternal syphilis during pregnancy is the direct cause of congenital syphilis, which reached 3,882 cases in 2023. Treatment with penicillin during pregnancy prevents virtually all cases.

  3. 3

    People with HIV or on PrEP

    Test at every PrEP follow-up visit (every 3 months) and at least annually with HIV. People with HIV are at higher risk of acquiring syphilis and, if coinfected, at significantly higher risk of neurosyphilis and ocular complications. An open syphilis sore also makes HIV easier to transmit and acquire.

  4. 4

    Anyone with a new sore, rash or known exposure

    A painless genital, anal or mouth ulcer — or an unexplained non-itchy rash covering the palms and soles — warrants same-day testing. If a partner or recent contact tests positive for any stage of syphilis, get tested immediately regardless of symptoms.

  5. 5

    People with multiple or anonymous partners

    Routine annual screening catches the silent latent stage, which has no symptoms at all. You cannot tell by looking at someone — or by how you feel — whether syphilis is present.

  6. 6

    People experiencing homelessness, incarceration or substance use

    Intersecting structural vulnerabilities drive disproportionately high rates in these populations. Opportunistic screening at shelter intake, jails and harm-reduction programs catches the infection in people who may not otherwise access testing.

Symptoms

What are the symptoms of syphilis?

Syphilis is easy to miss at every stage. The primary sore is painless and heals on its own. The secondary rash can be subtle or confused with a drug reaction. The latent stage has no symptoms at all — yet the infection is still there, still doing damage, and still detectable only by a blood test. Symptoms follow the stage: the chancre appears 10–90 days after exposure (average 21 days); the secondary rash develops 2–12 weeks after the primary sore heals; the latent stage is defined by the complete absence of symptoms. That's exactly why testing matters — you can have it, pass it on, and never feel a thing.

Primary (≈10–90 days, avg 21 days post-exposure)

  • One firm, round, painless ulcer (chancre) at the infection site — genitals, anus, lips or throat
  • Swollen lymph nodes near the sore (in the groin for genital chancres)
  • Heals without treatment in 3–6 weeks, but the bacteria remain and the infection progresses

Secondary (2–12 weeks after primary heals)

  • Non-itchy rash — often copper-colored, rough — classically covering the palms of the hands and soles of the feet
  • Condylomata lata: flat, moist, wart-like patches in skin folds (groin, armpits, under the breasts) — highly contagious
  • Flu-like illness: fever, swollen lymph nodes throughout the body, sore throat, fatigue, headache, muscle aches
  • Patchy hair loss (moth-eaten alopecia)
  • Mucous patches — white-gray flat sores inside the mouth or on the tongue

Latent (after secondary resolves)

  • No symptoms whatsoever — the only sign of infection is a positive blood test
  • Early latent (< 1 year since infection): still transmissible; secondary relapse is possible
  • Late latent (> 1 year or unknown): not sexually transmissible; bacteria dormant in tissue

Tertiary (years to decades later, ~25–30% of untreated cases)

  • Gummas: soft, granulomatous lesions that destroy skin, bone and internal organs
  • Cardiovascular: aortic aneurysm (especially ascending aorta), aortic regurgitation — can be fatal
  • Neurosyphilis: dementia, personality change, loss of coordination (tabes dorsalis), paralysis
  • Ocular/otic: vision loss, hearing loss — can occur at any stage, not only tertiary

Symptoms are an unreliable guide at every stage. A blood test is the only way to confirm or rule out syphilis — and positive treponemal tests stay reactive for life, even after cure.

Disease progression

How does syphilis progress?

Syphilis progresses through distinct stages — each with different symptoms, contagiousness, and consequences. Catching it early means a simpler cure; the later stages require more aggressive treatment and carry serious risks.

  1. 1

    Primary

    10–90 days after exposure (average 21 days) Contagious

    The first sign of syphilis is a single, firm, painless ulcer called a chancre at the site where <em>T. pallidum</em> entered the body — most often the genitals, anus, lips or throat. It has a clean, hard, raised edge, a clean base, and causes no pain, which is why it goes unnoticed so easily. The sore disappears on its own in 3–6 weeks even without treatment, giving a false sense that the problem has resolved. It has not — the bacteria have disseminated through the bloodstream and the infection is progressing to the secondary stage.

    • Single (occasionally multiple) firm, round, painless ulcer at the infection site
    • Swollen, rubbery lymph nodes near the sore (groin nodes for genital chancres)
    • No fever, no systemic illness in most cases
  2. 2

    Secondary

    2–12 weeks after the primary chancre heals Contagious

    <em>Treponema pallidum</em> has now spread through the bloodstream and seeded tissues throughout the body. The hallmark is a rough, non-itchy rash that often appears on the palms of the hands and soles of the feet — a distinctive pattern that should prompt immediate testing. Condylomata lata — flat, moist, highly contagious gray-white patches — appear in warm skin folds. A flu-like illness with fever, swollen lymph nodes, sore throat and deep fatigue accompanies the skin findings. Secondary symptoms resolve on their own in weeks to months without treatment, after which the infection enters the latent phase. Many people who have had syphilis can date their infection from this stage if they recognized the rash.

    • Non-itchy rash on trunk, palms and soles — may be faint or easily confused with other rashes
    • Condylomata lata: flat, moist, gray-white patches in skin folds — highly infectious
    • Fever, generalized lymph node swelling, sore throat, fatigue, headache, myalgias
    • Patchy, moth-eaten hair loss on the scalp and eyebrows
    • Mucous patches: painless flat sores inside the mouth, vagina or anus
  3. 3

    Latent

    After secondary resolves; can persist for years to decades Not contagious

    Latent syphilis has no symptoms — the only evidence of infection is a positive blood test. It is divided into early latent (less than one year since the original infection, based on history, prior negative tests or documented exposure) and late latent (more than one year or unknown duration). During early latent, sexual transmission to partners is still possible and secondary relapse can occur. During late latent, sexual transmission is extremely rare, but the bacteria are not gone — they remain dormant in tissues. Without treatment, 25–30% of people with latent syphilis will eventually develop tertiary disease. Latent syphilis in a pregnant person, at any duration, can still infect the fetus.

    • None — by definition this stage is completely asymptomatic
    • Positive blood tests (both treponemal and nontreponemal) are the only finding
  4. 4

    Tertiary

    Years to decades after initial infection; in ~25–30% of untreated cases Not contagious

    Tertiary syphilis represents the body's inflammatory response to persistent <em>T. pallidum</em> infection and is defined by three overlapping manifestations. Gummatous syphilis produces soft, tumor-like granulomas (gummas) in the skin, bone, liver and other organs; locally destructive, they can erode bone and perforate the hard palate. Cardiovascular syphilis causes inflammation of the aortic wall (aortitis), most dangerously in the ascending aorta, leading to aortic aneurysm and aortic valve regurgitation — complications that can be lethal even decades after the original infection. The third manifestation is neurosyphilis, detailed separately below. All tertiary manifestations are now rare in countries with accessible testing and treatment — but they are a reminder of what syphilis does when it goes unchecked.

    • Gummas: firm, rubbery, slow-growing lesions on skin, bone or internal organs
    • Chest pain, shortness of breath, aortic regurgitation murmur (cardiovascular syphilis)
    • Progressive neurological and psychiatric symptoms (neurosyphilis)
  5. 5

    Neurosyphilis & Ocular Syphilis

    Can occur at any stage — early or late Not contagious

    <em>Treponema pallidum</em> can invade the central nervous system early in infection — meningeal involvement may begin during the secondary stage. Early neurosyphilis presents as aseptic meningitis: severe headache, stiff neck, fever, cranial nerve palsies. Late neurosyphilis, which develops after years of untreated infection, produces two classic syndromes: general paresis (progressive dementia, personality change, psychosis) and tabes dorsalis (degeneration of the posterior spinal cord causing loss of position sense, lightning pains and an unsteady, wide-based gait). Ocular syphilis — uveitis, retinitis, optic neuritis — can cause permanent vision loss and may be the sole presenting finding. Otic syphilis causes sensorineural hearing loss. These complications require urgent evaluation with cerebrospinal fluid analysis and IV penicillin.

    • Severe headache, neck stiffness, photophobia (meningeal)
    • Cranial nerve palsies (facial weakness, hearing loss, diplopia)
    • Eye pain, redness, blurred vision, floaters, vision loss (ocular)
    • Personality and psychiatric changes, progressive memory loss (general paresis)
    • Lightning-bolt leg pains, loss of position sense, wide-based gait (tabes dorsalis)
    • Hearing loss, tinnitus, vertigo (otic syphilis)
  6. 6

    Congenital Syphilis

    Transmitted in utero; early congenital = birth to 2 years; late congenital = after 2 years Not contagious

    Congenital syphilis occurs when <em>T. pallidum</em> crosses the placenta from an infected pregnant person to the fetus. Transmission can happen at any stage of pregnancy but is most efficient with untreated primary or secondary maternal syphilis. Early congenital syphilis — the form present at birth or appearing in the first two years — causes nasal discharge ("snuffles"), a desquamating skin rash, hepatosplenomegaly, severe hemolytic anemia, jaundice and diffuse bone abnormalities visible on X-ray. Late congenital syphilis, emerging after age two, produces the classic Hutchinson triad: notched "peg" incisors, interstitial keratitis (corneal scarring causing blindness) and sensorineural hearing loss. Saddle-nose deformity, saber shins and Clutton joints (knee swelling) are additional late stigmata. In 2023, 3,882 newborns in the U.S. were diagnosed with congenital syphilis — contributing to 279 stillbirths and neonatal deaths. Every case is preventable: a blood test at the first prenatal visit, repeated testing at 28 weeks and delivery in high-prevalence areas, and penicillin treatment stops transmission.

    • Nasal discharge ("snuffles"), maculopapular rash, desquamation (early)
    • Hepatosplenomegaly, jaundice, severe anemia (early)
    • Bone pain and radiographic periostitis (early)
    • Hutchinson teeth: small, widely spaced, notched permanent incisors (late)
    • Interstitial keratitis: corneal inflammation leading to blindness (late)
    • Sensorineural hearing loss, saber shins, saddle-nose deformity (late)

Left untreated

Why syphilis is worth catching early

Treated early, syphilis clears with antibiotics and causes no lasting harm. Left untreated, it can climb into the reproductive tract and beyond:

Neurosyphilis

Invasion of the brain and spinal cord by <em>T. pallidum</em> can occur at any stage of infection, not just late disease. Early involvement causes aseptic meningitis and cranial nerve palsies. Late neurosyphilis produces general paresis — a progressive dementia with personality change that historically filled psychiatric wards — and tabes dorsalis, a degeneration of the posterior spinal columns causing ataxia, lightning pains and loss of position sense. Diagnosis requires cerebrospinal fluid analysis (CSF-VDRL, CSF cell count and protein). Treatment demands IV aqueous penicillin G for 10–14 days.

Ocular and Otic Syphilis

Syphilis can directly infect the eye (uveitis, retinitis, optic neuritis) causing pain, floaters, blurred vision and, without treatment, permanent blindness. Otic syphilis produces sensorineural hearing loss, tinnitus and vertigo that may be sudden or progressive. Both can occur at any stage and are classified as neurosyphilis for treatment purposes — IV penicillin, not a single IM shot.

Cardiovascular Syphilis

Aortitis from tertiary syphilis causes aneurysm of the ascending aorta and aortic valve regurgitation, typically appearing 10–30 years after untreated infection. The result can be sudden aortic dissection or progressive heart failure. Unlike gummatous disease, cardiovascular syphilis damage cannot be reversed by antibiotic treatment — penicillin prevents further progression, but the structural damage remains.

Gummatous Disease

Gummas are soft, tumor-like granulomatous lesions produced by the immune response to chronic <em>T. pallidum</em> infection. They appear in the skin, bones, liver and other organs, causing local destruction — palatal perforation, bone erosion, hepatic nodules — that can be disfiguring. Unlike cardiovascular neurosyphilis complications, gummas respond well to penicillin treatment.

Congenital Syphilis

Transmission from pregnant person to fetus causes a spectrum of disease from miscarriage and stillbirth to severe multi-organ involvement at birth and lifelong stigmata including blindness, deafness and bone deformity. All 3,882 U.S. cases in 2023 were preventable. The CDC now recommends that pregnant patients test for syphilis at the first prenatal visit, again at 28 weeks, and again at delivery in high-burden jurisdictions.

HIV Acquisition and Transmission

An open syphilis sore is a direct portal for HIV. The inflammation and disrupted epithelium at the chancre site substantially increase both the risk of acquiring HIV during sex and the risk of transmitting it. Studies estimate a 2–5-fold increased HIV acquisition risk in the presence of genital ulcer disease, including syphilitic chancres.

U.S. data

How common is syphilis in the U.S.?

Men who have sex with men account for 36% of all P&S syphilis cases, and the rate among MSM is more than 100 times the rate in heterosexual men. Congenital syphilis cases rose to 3,882 in 2023 — a ten-year high driven by gaps in prenatal screening. The chart below tracks syphilis against the other reportable STIs since the 2020 pandemic dip.

15.8 /100k
P&S syphilis rate (per 100,000) (2023)
209k
Total cases, all stages (2023)
3,882
Congenital syphilis cases (2023)

Reported STD rates in the U.S. over time (per 100,000)

Chlamydia ▼ 1% vs 2022
Chlamydia Gonorrhea Syphilis (P&S)
0 250 500 2020202120222023

Between 2020 and 2023 in the U.S., chlamydia has risen from 476.7 to 492.2 per 100,000 (3%), gonorrhea has fallen from 204.5 to 179.5 per 100,000 (12%), and P&S syphilis has risen from 12.6 to 15.8 per 100,000 (25%).

The 2020 dip reflects reduced pandemic-era screening, not lower transmission. Source: CDC NCHHSTP AtlasPlus / STI Surveillance 2023.

Reported rates vary widely by state and county — see the by-location links below for syphilis testing and local surveillance data where you live.

How testing works

How a syphilis test works

Syphilis is detected with a nucleic-acid amplification test (NAAT) — the most accurate method — on a urine sample or a swab. You can do it at a lab, a clinic, or at home.

When to test

For a reliable blood test result, test at least 6 weeks after a potential exposure. If you test earlier and the result is negative but you have a sore or a confirmed exposure, re-test at 6 weeks and again at 3 months. A single negative test does not rule out very recent infection.

After treatment

After treatment, follow-up RPR or VDRL titers (not treponemal tests) confirm cure at 6, 12 and 24 months — a fourfold decline in titer is the standard benchmark for successful treatment. Treponemal tests typically remain reactive for life even after successful treatment and cannot be used to monitor cure.

Non-treponemal test (RPR / VDRL) Standard screen
Sample
Blood draw or finger-prick
Results
1–3 days

The standard initial screening test. Results include a titer (e.g., 1:16) that reflects disease activity and is used to monitor treatment response — a fourfold drop (e.g., 1:16 → 1:4) confirms successful treatment. Can produce biological false positives in pregnancy, autoimmune conditions (especially lupus), acute viral infections and IV drug use.

Treponemal test (TPPA / FTA-ABS / EIA) Confirmatory
Sample
Blood draw
Results
1–3 days

Confirms a positive non-treponemal screen by detecting antibodies specific to <em>T. pallidum</em>. The TPPA (Treponema pallidum particle agglutination assay) and FTA-ABS are confirmatory; EIA (enzyme immunoassay) is often automated and used for high-volume screening in the reverse-sequence algorithm. Remain positive for life after cure — cannot be used to judge treatment success or re-infection.

Reverse-sequence screening (EIA → RPR) Lab algorithm
Sample
Blood draw
Results
1–3 days

Many hospital and commercial labs now perform treponemal EIA first (automated, high-throughput), then reflex to RPR only if positive. A positive EIA with negative RPR is a common result in someone cured years ago — it means past infection, not active disease. This pattern requires careful clinical interpretation and sometimes a second treponemal test (TPPA) to resolve.

Darkfield microscopy / PCR of sore Early detection
Sample
Swab of fluid from an active chancre
Results
Same day (darkfield) to 1–3 days (PCR)

Detects the spirochete directly in primary syphilis before antibody tests turn positive. Darkfield requires a trained microscopist and viable organisms and is rarely available outside specialized STI clinics. PCR of sore fluid is increasingly preferred where available and is more sensitive. Either test confirms primary syphilis even during the antibody window period.

Cerebrospinal fluid analysis (for neurosyphilis) Neurosyphilis only
Sample
Lumbar puncture (CSF)
Results
1–3 days

Required to diagnose or rule out neurosyphilis in patients with neurological or ocular symptoms, HIV and syphilis coinfection, or treatment failure. Key findings: CSF-VDRL (specific but insensitive), elevated white cell count (> 5 cells/μL), elevated protein. A positive CSF-VDRL in the right clinical context confirms neurosyphilis.

What it costs: ~$24–$80 self-pay for a syphilis blood test at a private lab; at-home kits and bundled STI panels run approximately $45–$150. Free or sliding-scale at health departments, Title X family planning clinics and federally qualified health centers (FQHCs) — and prenatal syphilis screening is routine standard of care. Covered with no out-of-pocket cost for recommended screening (including all pregnant people) under most ACA-compliant plans, under USPSTF Grade B recommendation.

If your result is positive

How is syphilis treated?

Syphilis is cured with penicillin. <em>Treponema pallidum</em> has never developed documented resistance to penicillin — it remains the unambiguous gold standard after 70 years of use. The specific regimen depends on the stage of infection: early syphilis needs a single intramuscular injection; late syphilis needs three weekly injections; neurosyphilis demands IV penicillin administered in a hospital or infusion setting. There is no effective oral or over-the-counter alternative, and self-treatment is not possible. Partner notification and treatment are as important as your own cure — re-infection from an untreated partner is common.

StageRecommended regimen
Primary, secondary, or early latent (< 1 year)Benzathine penicillin G 2.4 million units IM, single dose
Late latent (≥ 1 year or unknown duration) or tertiary (non-neurological)Benzathine penicillin G 2.4 million units IM, once weekly × 3 doses (7.2 million units total)
Neurosyphilis, ocular syphilis, otic syphilisAqueous crystalline penicillin G 18–24 million units per day IV, administered as 3–4 million units every 4 hours or continuous infusion × 10–14 days
Penicillin allergy (non-pregnant only) — primary, secondary or early latentDoxycycline 100 mg orally twice daily × 14 days
Penicillin allergy (non-pregnant only) — late latent or unknown durationDoxycycline 100 mg orally twice daily × 28 days

Treat partners

Every sex partner needs to be notified and tested based on CDC exposure windows: partners from the 3 months preceding symptoms for primary syphilis; 6 months for secondary; 1 year for early latent. Do not resume sexual activity until the chancre has fully healed and you have completed treatment — for a single-dose injection, that typically means waiting until the sore is gone. Partners should receive treatment presumptively if they cannot be tested promptly.

In pregnancy

Penicillin G is the only acceptable treatment for syphilis in pregnancy — no alternative antibiotic has been shown to reliably prevent congenital syphilis, and doxycycline and tetracyclines are contraindicated in pregnancy. A pregnant patient with documented penicillin allergy must undergo penicillin desensitization (a supervised protocol over 4–6 hours) and be treated with penicillin. The Jarisch-Herxheimer reaction — fever, chills, uterine contractions — can trigger preterm labor or fetal distress during the first 24 hours after treatment and should be managed in a monitored setting with antipyretics; patients must be counseled beforehand.

Re-test after treatment

Test of cure uses non-treponemal titers (RPR or VDRL) at 6, 12 and 24 months after treatment. A fourfold decline in titer (e.g., 1:16 → 1:4) by 6–12 months confirms successful treatment of primary and secondary syphilis. Failure to achieve this decline — or a fourfold rise in titer — indicates either treatment failure or re-infection. Treponemal tests (TPPA, FTA-ABS) remain reactive for life after cure and cannot be used to monitor treatment response.

Treatment & online care

Resistance note: Penicillin-resistant <em>Treponema pallidum</em> has never been documented. This makes syphilis an outlier among bacterial STIs — penicillin remains first-line after seven decades with zero documented resistance. Doxycycline works as an alternative for non-neurological, non-pregnant cases but has a lower evidence base than penicillin IM. Azithromycin is no longer recommended — resistance (the A2058G mutation in 23S rRNA) has emerged globally and is now common in the U.S.

Watch for: The most clinically significant side effect of treatment is the Jarisch-Herxheimer reaction: fever, rigors, headache, myalgia and hypotension occurring within 2–8 hours of the first penicillin dose, usually resolving within 24 hours. It is caused by the rapid release of bacterial antigens during spirochete death — it is not an allergic reaction and is not a reason to stop treatment. Manage with acetaminophen and reassurance. It is more common and more pronounced in primary and secondary syphilis than in latent syphilis. True penicillin allergy (anaphylaxis) is much rarer and distinct from Jarisch-Herxheimer.

Prevention

How to prevent syphilis

  • Test on a schedule — not just when you have symptoms

    Routine screening is the single most effective prevention strategy. The primary chancre is painless, the latent stage is completely asymptomatic, and symptoms are an unreliable guide. MSM should test every 3–6 months; everyone pregnant at the first prenatal visit; anyone on PrEP at every follow-up. Catching syphilis early means one injection instead of three — or IV penicillin — and prevents transmission to partners and fetuses.

  • Use condoms consistently

    Condoms substantially reduce syphilis risk by covering the sites most likely to harbor or contact sores during sex. But a sore outside the condom-covered area — on the scrotum, perineum, mouth or anus — can still transmit the infection. Condoms are a meaningful layer of protection, not a guarantee, which is why they work best alongside regular testing.

  • Treat partners before resuming sex

    If you test positive, notify every sexual partner from the relevant exposure window — your clinician or local health department can help with anonymous partner notification if needed. Avoid sex until the chancre has fully healed and treatment is complete. Your partner's treatment protects both of you: re-infection from an untreated partner resets the clock entirely and may not show up immediately on a blood test.

  • Consider doxy-PEP if you're at elevated risk

    Doxycycline post-exposure prophylaxis (doxy-PEP) — 200 mg taken within 72 hours of condomless sex — reduces syphilis, chlamydia and gonorrhea risk by roughly 50–80% in MSM and transgender women in clinical trials. The CDC supports its use in this population as of 2023. Ask a clinician whether it is appropriate for you.

  • Prenatal screening protects your baby

    Every case of congenital syphilis in 2023 was preventable. If you are pregnant — or planning to become pregnant — get screened for syphilis at your first prenatal visit. In high-prevalence states, rescreening at 28 weeks and delivery is standard. Treatment with penicillin during pregnancy, even in the third trimester, prevents most cases of transmission to the newborn.

Who is most at risk

Who is most at risk for syphilis?

Anyone who is sexually active can contract syphilis, but certain groups face significantly higher risk — and should test more frequently.

Gay and bisexual men (MSM)
MSM account for approximately 36–47% of all primary and secondary syphilis cases in the U.S., despite representing about 4% of the adult male population. The rate of P&S syphilis among MSM is more than 100 times the rate in heterosexual men. Frequent testing — every 3 months for those with multiple partners, at PrEP visits, or with HIV — is the primary tool for interrupting transmission in this population.
~36–47% of all U.S. P&S syphilis cases
People with HIV
HIV and syphilis coinfection is common because they share transmission networks. People with HIV who acquire syphilis are at meaningfully higher risk of neurosyphilis and ocular syphilis complications, and may require more intensive follow-up monitoring after treatment. Active syphilis in a person with HIV increases HIV viral load in blood and genital secretions, raising transmission risk to sexual partners.
HIV coinfection significantly increases risk of neurosyphilis complications
People on PrEP
PrEP use does not protect against syphilis, gonorrhea or chlamydia. Because PrEP is prescribed to people at elevated HIV risk — who often have characteristics associated with higher STI exposure — syphilis rates among PrEP users are substantially higher than in the general population. CDC guidelines recommend syphilis screening at every PrEP follow-up visit (every 3 months). PrEP clinic visits are the ideal touchpoint for routine STI screening.
CDC recommends syphilis screening every 3 months for people on PrEP
Pregnant people
Any stage of syphilis during pregnancy can be transmitted to the fetus. The probability of transmission is highest — approaching 80% — with untreated primary or secondary syphilis in the first trimester or early second trimester. Late syphilis carries lower (but nonzero) transmission risk. Without prenatal screening, congenital syphilis goes undetected until it causes miscarriage, stillbirth, or severely symptomatic newborn disease.
Transmission risk ~80% with untreated P&S syphilis in early pregnancy
African American, Hispanic/Latino and American Indian/Alaska Native communities
Rates of syphilis are 2–5 times higher among Black and American Indian/Alaska Native populations compared to white Americans — a disparity driven by structural factors including limited access to healthcare, historical underinvestment in STI programs, residential segregation and concentrated poverty, not by individual behavior. Equitable access to testing and treatment — not blame — is the public health response.
2–5× higher P&S syphilis rates than white Americans
People experiencing homelessness, incarceration or substance use
These populations face intersecting barriers to testing and treatment: lack of stable housing, limited healthcare access, distrust of institutions and barriers to partner notification. Methamphetamine and other stimulant use is specifically associated with sexual risk behaviors and high syphilis rates in community studies. Integrated, low-barrier testing at jails, shelters and harm-reduction programs is critical.
Intersecting structural vulnerabilities drive disproportionate burden

Why it matters

Why STD testing matters

Find syphilis testing
  • Syphilis is the great imitator — the early sore is painless, the infection goes silent for years, and symptoms at every stage mimic other conditions. A blood test is the only reliable way to know your status.
  • Penicillin cures the infection but cannot undo damage already done. Neurosyphilis, blindness, aortic aneurysm and congenital disability are all preventable — but only if you catch and treat syphilis before those complications develop.
  • The U.S. is in a syphilis surge: 3,882 newborns were infected in 2023, and every one of those cases was preventable with a prenatal blood test and a penicillin shot.
  • Testing is fast, private and often free. A blood draw, results in 1–3 days, and a single injection clears early syphilis completely.

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Deeper guides from our editorial library on syphilis and related topics.

Living with syphilis

Questions to ask your provider about syphilis

Syphilis is common, treatable, and nothing to be ashamed of — millions of Americans are diagnosed every year. The most useful next step after a positive result (or before a first test) is a direct conversation with a clinician. Here are the questions that matter most:

  • Is my syphilis test result definitive, or do I need a confirmatory test?
  • What treatment options are available to me, and how long until I'm no longer contagious?
  • Should I notify my recent partners, and can your office help me do that confidentially?
  • How soon can I re-test to confirm the infection has cleared?
  • Are there other STIs I should test for at the same visit?
  • Can this affect my fertility, pregnancy, or long-term health if left untreated?

Good to Know

Syphilis testing FAQs

Common questions about syphilis and syphilis testing, answered.

How is syphilis diagnosed?

Syphilis is almost always diagnosed with a blood test — a quick draw or finger-prick that detects antibodies produced in response to <em>Treponema pallidum</em> infection. Two types of tests are used: non-treponemal tests (RPR or VDRL) screen for general antibody activity and produce a titer that tracks disease activity over time; treponemal tests (TPPA, FTA-ABS or EIA) confirm that the antibodies are specific to syphilis. Both are usually done together because neither type alone tells the whole story. If you have an active sore, a clinician can also swab it for direct microscopy or PCR, which detects the bacteria before the antibody tests become reactive.

What does a syphilis sore (chancre) look like?

The primary syphilis sore — called a chancre — is typically a single, firm, round ulcer with clean, raised edges and a smooth base. What makes it so deceptive is that it is almost always painless: no tenderness, no discharge, no bleeding. It appears at the site where <em>T. pallidum</em> entered the body, usually on the genitals, anus, lips or throat, and it often hides inside the vagina, rectum or throat where you can't see or feel it. The sore heals on its own in 3–6 weeks, which people routinely interpret as recovery — but the bacteria have simply moved deeper. If you notice a painless ulcer anywhere on your genitals or mouth, get a blood test immediately rather than waiting to see if it resolves.

How long after exposure should I test for syphilis?

Blood tests for syphilis — both RPR and treponemal tests — become detectable 1–4 weeks after the chancre appears, which is roughly 3–6 weeks after the sexual exposure that caused it. For the most reliable negative result, test at least 6 weeks after a potential exposure. If you test earlier and get a negative result but you have a sore, know you were exposed, or have symptoms of secondary syphilis, retest at 6 weeks and again at 3 months. A single early negative is not a green light. If you have an active sore, a clinician can swab it for direct testing even before the blood test turns positive.

Can syphilis be cured?

Yes — syphilis is completely curable with penicillin, which has been the treatment of choice for over 70 years with zero documented resistance. Primary, secondary and early latent syphilis (under one year) requires a single intramuscular injection of benzathine penicillin G. Late latent or unknown-duration syphilis requires three weekly injections. Neurosyphilis requires intravenous penicillin G given in a hospital or infusion setting for 10–14 days. The critical limitation: penicillin cures the infection and stops further damage, but it cannot reverse damage already done. Neurosyphilis that has caused dementia, aortic disease that has caused an aneurysm, or congenital infection that has caused deafness are not reversed by treatment. Getting tested and treated early is what prevents those outcomes.

What is the difference between an RPR and a TPPA test?

RPR (Rapid Plasma Reagin) is a non-treponemal test that detects antibodies produced during syphilis infection but not specifically targeted at <em>Treponema pallidum</em>. It is fast, inexpensive and quantitative — the titer (e.g., 1:32) reflects disease activity and falls with successful treatment, making it ideal for monitoring cure. TPPA (Treponema pallidum Particle Agglutination Assay) is a treponemal test that detects antibodies specifically targeting T. pallidum proteins. It is more specific — far fewer false positives — but it remains reactive for life even after successful treatment, so it cannot be used to assess whether treatment worked. In practice: RPR screens and monitors; TPPA confirms and diagnoses. Most labs now use a reverse-sequence algorithm: automated treponemal EIA first, then RPR if positive.

Why did my syphilis test come back positive if I was treated years ago?

This is one of the most common points of confusion about syphilis testing. Treponemal tests — TPPA, FTA-ABS, EIA — remain reactive for life after successful treatment. They detect antibodies specific to <em>Treponema pallidum</em> that the immune system produces and retains permanently, even after the bacteria are gone. A positive treponemal test in someone who was previously treated and cured does not indicate active infection or treatment failure. The test you need to distinguish past-cured infection from active infection is the RPR (or VDRL): after successful treatment, the RPR titer falls and eventually becomes non-reactive (or stays at a low, stable level called a "serofast" state). If your RPR is negative or at a stable low titer and you have no symptoms, you are almost certainly cured. If the RPR is rising, that indicates active infection requiring treatment.

Is syphilis dangerous even if I feel fine?

Yes — latent syphilis, which has no symptoms at all, is one of the most dangerous states to be in precisely because it is silent. The bacteria are not dormant in the sense of being inactive; <em>T. pallidum</em> persists in tissues throughout the body and, in 25–30% of untreated people, drives the development of tertiary disease years to decades later. Tertiary syphilis includes neurosyphilis (progressive dementia, loss of coordination), cardiovascular disease (aortic aneurysm, heart failure) and gummatous disease (destructive granulomas in skin, bone and organs). By the time those complications become symptomatic, significant irreversible damage has already occurred. The latent stage is also the time when a pregnant person can transmit the infection to a fetus. Feeling fine is not the same as being fine — a blood test is the only way to know.

What is the Jarisch-Herxheimer reaction?

The Jarisch-Herxheimer reaction is a predictable side effect of syphilis treatment that is often confused with a penicillin allergy — they are completely different things. It occurs when penicillin kills large numbers of <em>Treponema pallidum</em> rapidly, releasing bacterial antigens that trigger a systemic inflammatory response. Within 2–8 hours of the first treatment dose, you may develop fever (sometimes high), rigors, headache, muscle aches, sweating and a temporary flare of the syphilis rash. It typically peaks at about 8 hours and resolves within 24 hours. Manage it with acetaminophen and rest, and stay hydrated. It is more pronounced with primary and secondary syphilis than with latent disease. In pregnancy, the fever can trigger uterine contractions and fetal distress, which is why treatment in pregnant patients is given in a monitored setting. Experiencing this reaction does not mean penicillin is harming you — it means the treatment is working.

Can syphilis be passed to a baby?

<em>Treponema pallidum</em> crosses the placenta readily and can infect the fetus at any point during pregnancy, though transmission is most efficient — approaching 80% — with untreated primary or secondary maternal syphilis in the first or early second trimester. The results are severe: miscarriage, stillbirth, premature birth, and in liveborn infants, a constellation of findings called congenital syphilis including nasal discharge, widespread rash, hepatosplenomegaly, severe anemia, bone lesions and — appearing years later — Hutchinson teeth, corneal scarring and hearing loss. In 2023, 3,882 U.S. newborns were diagnosed with congenital syphilis and 279 died. Every one of those outcomes is preventable: a blood test at the first prenatal visit and a penicillin injection stops transmission to the baby. If you are pregnant and have not been tested for syphilis, get tested today.

Can you get syphilis from oral sex?

Yes. Syphilis is transmitted by direct contact with a sore — and chancres can form on the lips, tongue, throat and tonsils as readily as they form on genitalia. Performing oral sex on a partner who has a genital sore, or receiving oral sex from a partner who has an oral sore, both transmit syphilis. The oral chancre is often smaller and less visible than a genital one, and it is painless, so people with oral syphilis frequently don't know they have it. If your testing includes a throat swab for gonorrhea or chlamydia, it does not test for syphilis — you need a blood test specifically for syphilis.

How does syphilis affect people with HIV?

The relationship between syphilis and HIV runs in both directions. An open syphilis sore substantially increases both the acquisition and transmission risk for HIV — the disrupted epithelium and local inflammation at a chancre are a direct entry point for HIV. Conversely, in people who already have HIV, syphilis is more likely to cause unusual or accelerated manifestations: neurosyphilis and ocular syphilis occur more commonly and can appear earlier in the disease course than in HIV-negative individuals. Treatment for syphilis in people with HIV is generally the same as standard CDC regimens, but follow-up monitoring is more intensive because treatment response may be slower. People with HIV and syphilis coinfection should have careful clinical and serological follow-up at 3, 6, 9, 12 and 24 months.

What is neurosyphilis?

Neurosyphilis is invasion of the central nervous system by <em>Treponema pallidum</em>, and it can happen at any stage of syphilis — it is not exclusively a late or tertiary complication. Early neurosyphilis presents as aseptic meningitis: severe headache, stiff neck, fever and cranial nerve involvement (facial weakness, double vision, hearing loss). Late neurosyphilis — developing after years of untreated infection — produces two classic syndromes: general paresis, a progressive dementia with personality change and psychiatric symptoms; and tabes dorsalis, a degeneration of the posterior spinal cord causing stabbing leg pains, loss of position sense and an unsteady gait. Ocular syphilis (uveitis, retinitis, optic neuritis) is classified as neurosyphilis for treatment purposes and can cause permanent blindness. Neurosyphilis is diagnosed by examining spinal fluid (lumbar puncture) and is treated with high-dose IV penicillin G for 10–14 days — a single IM injection is not adequate.

Do I need to tell past partners if I test positive?

Yes — and this matters clinically, not just ethically. Partners who were exposed during your infectious period need to be tested and potentially treated, since they may have syphilis without knowing it and may be passing it on or developing complications. For primary syphilis, notify partners from the 3 months before your symptom onset; for secondary syphilis, 6 months; for early latent, 1 year. You can tell partners yourself, or your local health department's disease intervention specialist (DIS) can notify partners confidentially without revealing your name. Many areas also have online partner notification services. Avoiding sex with current partners until treatment is complete and the chancre has healed prevents re-infection.

Can syphilis come back after treatment?

The same infection cannot come back after successful treatment — penicillin permanently clears the bacteria. But syphilis confers no lasting immunity, so you can be re-infected from a new or untreated partner as easily as if you had never had it. Re-infection is common, particularly in communities with high syphilis rates and among people with multiple partners. Clinically, re-infection looks identical to a new infection: a rising RPR titer, often with symptoms, even in someone who was treated and confirmed cured. This is why follow-up blood testing at 6, 12 and 24 months matters — a rising titer indicates re-infection (or less commonly, treatment failure) and requires a new course of treatment.

How long is syphilis contagious?

The contagiousness of syphilis depends heavily on the stage. Primary syphilis — when active chancres are present — is highly contagious through sexual contact with those sores. Secondary syphilis — with its disseminated rash, condylomata lata and mucous patches — is also highly contagious; the condylomata lata in skin folds are particularly infectious because they are moist and teeming with spirochetes. Early latent syphilis (less than one year since infection) carries a risk of sexual transmission and also a risk of relapse to secondary symptoms. Late latent syphilis (more than one year) is not considered sexually transmissible. Tertiary syphilis is not contagious. Critically, a pregnant person with any stage of syphilis can transmit it to the fetus — including late latent. After a single IM penicillin injection, the risk of sexual transmission drops rapidly, but avoid sex until the treatment is complete and the sore has healed.

Editorial standards

Medically reviewed · Updated

Reviewed by Mark Riegel, MD · Sexual Health Physician · Chief Medical Reviewer

Physician focused on sexual health — STI testing, treatment and prevention — and EasySTD's chief medical reviewer. Owns the condition guides and is the clinical backstop for any page without a more specific specialist.

6 Sources

Clinical guidance

  1. CDC — STI Treatment Guidelines, 2021: Syphilis https://www.cdc.gov/std/treatment-guidelines/syphilis.htm
  2. CDC — Syphilis Detailed Fact Sheet https://www.cdc.gov/std/syphilis/stdfact-syphilis-detailed.htm
  3. CDC — Congenital Syphilis Fact Sheet https://www.cdc.gov/std/syphilis/stdfact-congenital-syphilis.htm
  4. USPSTF — Syphilis Infection Screening in Nonpregnant Adults and Adolescents https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/syphilis-infection-in-nonpregnant-adults-and-adolescents-screening

Data & references

  1. CDC — STI Surveillance 2023 https://www.cdc.gov/std/statistics/
  2. CDC NCHHSTP AtlasPlus — surveillance data https://www.cdc.gov/nchhstp/atlas/