Retesting After STI Treatment

When Should I Retest After STI Treatment?

If you’ve recently completed antibiotics for an STI, you may be wondering when it’s the right time to test again. Most tests look for the genetic “footprints” of an infection—not just live bacteria. Because of that, tests can sometimes stay positive for a short time after you’ve already been cured. Retesting too soon can cause stress and confusion.

Typical Retesting Timeframes

Subsection: Chlamydia & Gonorrhea

  • Tests may stay positive for up to 3–4 weeks after treatment.

  • Retesting earlier can give a false positive.

Retesting after treatment to detect repeat infections error processing SSI file. Centers for Disease Control and Prevention. July 22, 2021. Accessed August 29, 2025. https://www.cdc.gov/std/treatment-guidelines/clinical-retesting.htm. 

Subsection: Trichomoniasis & Mycoplasma genitalium

  • These infections may also show positive for around 3 weeks after treatment, though some infections may clear more quickly

  • Waiting 3–4 weeks before retesting gives the most accurate results.

Trichomoniasis - STI treatment guidelines. Centers for Disease Control and Prevention. September 21, 2022. Accessed August 29, 2025. https://www.cdc.gov/std/treatment-guidelines/trichomoniasis.htm. 

Subsection: Syphilis

  • Blood tests measure antibodies, which remain in your system for life—even after cure.

  • Instead of turning “negative,” your healthcare provider tracks your titer levels. These numbers should go down within 6–12 months after treatment.

Brown DL, Frank JE. Diagnosis and management of syphilis. Am Fam Physician. 2003 Jul 15;68(2):283-90. PMID: 12892348.

Why Timing Matters

  • Testing too soon may not give clear results, as it might detect leftover fragments from the infection.

  • A positive result from a test too early after treatment might not be indicative of active infection, making additional antibiotic treatment unnecessary - which can contribute to antibiotic resistance.

What if Symptoms Come Back?

If you notice symptoms returning before the 3–4 week window, don’t wait. Contact a healthcare provider right away to discuss retesting or retreatment.

Bottom Line

  • For most bacterial STIs: wait at least 3–4 weeks after completing antibiotics before retesting for accurate results.

  • For syphilis: follow your provider’s plan to track antibody levels over time.