About the Syphilis Test

Purpose of the test

A syphilis test shows whether your body has been exposed to Treponema pallidum, the bacterium that causes syphilis. Syphilis is a sexually transmitted infection (STI) that can cause serious health problems without treatment, and it often causes no symptoms at first, making testing the only reliable way to know your status.

Left untreated, syphilis moves through four stages, each with different signs and symptoms:

Primary Stage – a chancre typically appears about three weeks after exposure (10 to 90 days) on the genitals or mouth. Chancres are small and painless, and may resolve on their own within a few weeks, yet the infection still remains.
Secondary Stage – occurs one to six months after the chancre disappears, and a rough, bumpy rash takes its place and can cover most of your body. Other symptoms evolve, such as fever, fatigue, wart-like sores, and general malaise.
Latent Stage – a symptom-free period that can last for years, though the infection remains in the body.
Tertiary Stage – most people with untreated syphilis never reach this stage, but when it develops 10 to 30 years after infection it can cause serious problems, including brain damage and dementia, heart disease, seizures, and blindness.

Congenital syphilis occurs when syphilis is passed from an infected mother to her baby during pregnancy and can lead to miscarriage, stillbirth, serious lifelong health problems, and death.

The test serves three purposes:

Screening: Routine syphilis screening for sexually active adults at higher risk, including pregnant people, men who have sex with men, people with a history of drug use, sex work, or incarceration, and people living with HIV
Diagnosis: Testing when symptoms like a painless sore, skin rash on the palms or soles, or unexplained swollen lymph nodes suggest possible infection
Monitoring: Tracking quantitative antibody levels after treatment, with a four-fold titer decrease within six to 12 months as the standard benchmark

A syphilis blood test doesn’t detect active lesions directly. This test does not identify other STIs, but other STI tests may be ordered separately.

What does the syphilis test measure?

Most syphilis tests detect antibodies in your blood. Labs use two main types, and understanding both helps you read your report.

Nontreponemal tests: These screening tests include RPR (Rapid Plasma Reagin) and VDRL (Venereal Disease Research Laboratory). They detect antibodies your body produces in response to cell damage from the infection. They aren’t specific to syphilis bacteria, so a reactive result usually needs confirmation. Syphilis is a common STI that can be cured, and antibody levels drop after successful therapy, making these tests useful for monitoring treatment.
Treponemal tests: Fluorescent Treponemal Antibody Absorption (FTA-ABS) and Treponema pallidum particle agglutination (TPPA) are two tests that detect antibodies that specifically target Treponema pallidum. They confirm a syphilis infection after a reactive screening result. Treponemal antibodies often stay detectable for life, even after successful treatment, so these tests can’t tell you whether an infection is current or from the past.
Traditional algorithm: The lab runs a nontreponemal test (RPR or VDRL) first. If reactive, a treponemal test confirms the result.
Reverse algorithm: Many high-volume labs now start with a treponemal immunoassay. If reactive, they follow up with an RPR or VDRL to check for active infection. Your report may show two result lines for this reason.
Direct detection tests: Darkfield microscopy is a highly specific, rapid, and inexpensive test that is often used for on-site identification of T. pallidum. Fluid from a sore is placed under a special microscope (darkfield condenser) to directly observe the spiral-shaped bacteria, thus allowing for a quick and reliable diagnosis. Another test that is used to detect early-stage syphilis is PCR (polymerase chain reaction). If a swab of a syphilitic lesion is taken and submitted for PCR testing, it may show an active, current infection. It does not detect past infections.

The CDC’s syphilis laboratory guidance describes both algorithms in detail and explains how labs choose between them based on testing volume and patient population.

When should I get a syphilis test?

Consider testing if any of these apply:

A painless sore, rash on the palms or soles, or unexplained swollen lymph nodes
A possible exposure to syphilis through sexual contact
A sexual partner recently diagnosed with syphilis or another STI
Multiple sex partners or a new sex partner
Inconsistent condom use
A current pregnancy
An HIV diagnosis or current use of pre-exposure prophylaxis (PrEP)

For routine screening, the CDC’s STI screening recommendations advise:

All pregnant people at the first prenatal visit should be tested; rescreen at 28 weeks, and at delivery if at higher risk
Gay, bisexual, and other men who have sex with men (MSM) at least once a year; every three to six months if at higher risk
Anyone living with HIV at the first evaluation and at least annually afterward
Sexually active adults in communities with higher local syphilis rates
People taking PrEP (Pre-Exposure Prophylaxis) at each follow-up visit (every three months)

The U.S. Preventive Services Task Force gives syphilis screening an A recommendation for nonpregnant adolescents and adults at increased risk, meaning the evidence of benefit is strong.

How It Works

How to get tested

Syphilis testing is ordered through a healthcare provider, clinic, or sexual health program. Your provider sends the sample(s) to a CLIA-certified lab. You give a blood sample at a lab, clinic, or your provider’s office, and results come back through the provider’s patient portal. If chancres/sores are present, swab tests of the fluid may be taken, and if neurological involvement (neurosyphilis) is suspected, a spinal tap may be done.

Syphilis is included in the at-home STD test, which screens for chlamydia, gonorrhea, syphilis, HIV, herpes, hepatitis B, and trichomoniasis from a self-collected sample. At-home kits include instructions, collection materials, and prepaid shipping. Results are delivered through a secure online portal. This is a private option if you’d prefer to test from home.

Before the test

No fasting is needed. Food doesn’t affect antibody levels.

Tell your provider about any recent illnesses, vaccinations, or antibiotic use. According to CDC syphilis treatment guidelines, false-positive nontreponemal test results can be associated with multiple conditions unrelated to syphilis, including autoimmune conditions, vaccinations, injection drug use, pregnancy, older age, and other infections. Penicillin G is the preferred medication for treatment. Current penicillin treatment for another condition could affect results. Your provider needs this context to read your results accurately.

During the test

Check in at the lab or clinic. Bring a photo ID and any order confirmation.
A phlebotomist draws blood from a vein in your arm. You’ll feel a brief pinch. The draw takes about two minutes.
A small bandage covers the site afterward; leave it on until bleeding stops.

The whole visit takes about 15 minutes. Some people notice light bruising at the draw site over the next day or two. That’s normal. Call your provider if you have lasting pain, swelling, or signs of infection at the site.

If a sore is present, a provider may swab fluid from it for direct testing. That’s a brief, slightly uncomfortable collection done in a clinical setting. In rare cases where neurosyphilis (syphilis affecting the brain and nervous system) is suspected, a lumbar puncture to collect cerebrospinal fluid may be needed.

After the test

Results are typically ready within one to three business days after the lab receives your sample, though timing can vary by lab. You’ll get results through the ordering provider’s patient portal or office.

What Do My Results Mean?

Syphilis results aren’t always a single positive or negative. Labs often run two tests on the same sample, so your report may show two result lines: one from a nontreponemal test (RPR or VDRL) and one from a treponemal test (FTA-ABS, TPPA, or an enzyme immunoassay, EIA). Reading them together tells the full story. The MedlinePlus VDRL test explainer describes what each result line means in plain language.

If your results are non-reactive (negative)

No antibodies were detected. “Non-reactive” is the standard term for a negative syphilis antibody result. If you tested within three to six weeks of a possible exposure, the infection may not have been detectable yet. A negative result in that window doesn’t rule out infection. Retest after the window closes if exposure was confirmed or symptoms develop.

If your results are reactive (positive)

Antibodies were found. But a reactive nontreponemal result (RPR or VDRL) alone isn’t a confirmed diagnosis. These tests have a known false-positive rate. Conditions like pregnancy, lupus, antiphospholipid syndrome, recent vaccination, or a viral infection like Epstein-Barr virus can trigger a reactive RPR or VDRL without syphilis being present.

That’s why a confirmatory treponemal test (FTA-ABS or TPPA) is also done on the same sample. If both tests are reactive, syphilis infection is confirmed. Your provider will recommend treatment, most often with penicillin. Syphilis is curable. Early treatment stops the infection from progressing.

After treatment, quantitative RPR titers are monitored at six and 12 months. A four-fold drop in titer confirms the treatment worked. Notify recent sexual partners so they can get tested and treated too.

If the treponemal test is non-reactive after a reactive nontreponemal result, the initial result was likely a false positive. Your provider will review your full history and may recommend retesting.

FAQs

What are the types of syphilis tests?

There are two main types. Nontreponemal tests (RPR and VDRL) screen for antibodies produced during infection and are used for both screening and treatment monitoring. Treponemal tests (FTA-ABS and TPPA) detect antibodies specific to the syphilis bacteria and confirm a reactive screening result. Most labs run both on the same blood sample.

Can a syphilis test give a false-positive result?

Yes. Nontreponemal tests like the RPR and VDRL have a known false-positive rate. Conditions that can trigger a false positive include pregnancy, lupus, antiphospholipid syndrome, recent vaccination, and some viral infections. A confirmatory treponemal test resolves most false positives.

What does a non-reactive syphilis test result mean?

Non-reactive means no syphilis antibodies were detected in your blood. If you tested within three to six weeks of a possible exposure, the window period may not have passed yet. Retest after the window closes if exposure was confirmed.

Should I get a syphilis test during pregnancy?

Yes. The U.S. Preventive Services Task Force recommends that everyone who is pregnant be screened for syphilis as early as possible. Babies born to people with untreated syphilis may be stillborn or die from the infection as a newborn. Infected infants (<2 years old) may have bone abnormalities, enlarged liver or spleen, jaundice, anemia, runny nose, or peeling skin. Some may develop neurosyphilis, resulting in stroke, eye abnormalities, or seizures. These problems also exist for infants 2 years and older, in addition to hearing loss, and notched teeth (Hutchinson’s teeth). Pregnant people at higher risk should be retested at 28 weeks and at delivery. Treatment with penicillin during pregnancy is safe and effective.

What is a confirmatory syphilis test?

A confirmatory test is a treponemal test (FTA-ABS or TPPA) run after a reactive screening result. It detects antibodies that specifically target Treponema pallidum. If it’s also reactive, syphilis infection is confirmed. If it’s non-reactive, the initial result was likely a false positive.

Can syphilis be tested with a urine sample?

No. Standard syphilis testing requires a blood sample. Urine doesn’t contain the antibodies used to detect syphilis. If a sore is present, a provider may collect fluid from it for direct testing, but blood remains the standard sample type.