Syphilis testing: what to expect and how to act

Syphilis is on the rise in many places, so testing matters more than ever. A test is the only way to know if you have it—symptoms can be mild or missed entirely. This guide explains the common tests, when to test, how results read, and the next steps you can take.

Types of syphilis tests and how they work

There are two main kinds of blood tests: nontreponemal and treponemal. Nontreponemal tests (RPR, VDRL) check for antibodies your body makes when infected. They’re cheap, fast, and useful to monitor treatment because their numbers (titers) fall after successful treatment.

Treponemal tests (TPPA, FTA-ABS) look for antibodies specific to the syphilis bacterium. These usually stay positive for life after infection, so they tell you if you ever had syphilis but not if it’s active now.

For sores or genital lesions, clinicians may use direct tests like dark-field microscopy or NAAT (nucleic acid amplification) to detect the bacteria from the lesion itself. Rapid point-of-care tests exist too; they give quick answers but might need confirmation with lab tests.

When to test and how to interpret timing

After exposure, antibodies take time to appear. Most tests become reliable 3–6 weeks after exposure; some people need up to 12 weeks. If you test too early, you can get a false negative. If you had a recent risky encounter, repeat testing is wise: once at 4–6 weeks and again at 3 months.

Interpreting results: a reactive nontreponemal plus a reactive treponemal test usually means current or past infection. If only treponemal is positive, it may be an old treated infection. A positive nontreponemal with a negative treponemal can be a false positive—pregnancy, autoimmune issues, and other infections can cause that.

Clinicians also use titers from nontreponemal tests to decide if treatment worked. A fourfold drop in titer (for example, from 1:32 to 1:8) usually shows good response to treatment.

Where to get tested: sexual health clinics, your doctor, community health centers, and some pharmacies offer testing. Home testing kits are available in some countries; confirm positive home results with a lab test and talk to a clinician about treatment.

If you test positive, antibiotic treatment—most commonly penicillin—clears the infection in most cases. Tell recent sexual partners so they can get tested and treated. Follow-up testing is important to make sure treatment worked.

Simple prevention steps cut risk: use condoms, limit new partners, and get tested regularly if you’re sexually active or have multiple partners. If you’re pregnant, ask for syphilis testing early—untreated syphilis can harm the baby.

Got questions about a specific result or timing? A sexual health clinic or your doctor can explain your lab report and plan the next steps with you.