What is the treatment for syphilis and how is cure confirmed?

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Last updated: February 7, 2025View editorial policy

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From the Guidelines

Syphilis treatment is typically achieved with a single intramuscular injection of 2.4 million units of benzathine penicillin G.

Treatment Details

  • For early-stage syphilis (primary, secondary, or early-latent), a single dose of 2.4 million units of benzathine penicillin G is effective, regardless of HIV status 1.
  • For late latent syphilis, three benzathine penicillin G injections given 1 week apart are recommended 1.
  • HIV-infected persons with early syphilis may be at increased risk for neurologic complications and treatment failure, but standard treatment recommendations are still applied 1.

Cure Confirmation

  • Assessment of therapeutic efficacy is complicated by the lack of a well-defined serologic response, with approximately 15% of patients not meeting standard criteria for serologic cure 12 months after treatment 1.
  • Cure is typically confirmed by the absence of sustained transmission and the absence of new cases, rather than a specific serologic test result 1.
  • The use of benzathine penicillin G remains the recommended treatment due to its long history of effectiveness and lack of data supporting alternative regimens 1.

From the Research

Treatment for Syphilis

  • The standard treatment for syphilis is benzathine penicillin G (BPG), with the dosage and administration method depending on the stage of the disease 2, 3, 4.
  • For early syphilis, a single intramuscular injection of 2.4 million U of BPG is commonly used, with reported treatment success rates of 90% to 100% 4.
  • For late-latent or syphilis infection of unknown duration, multiple intramuscular injections of BPG are typically used, although a single subcutaneous infusion of long-acting penicillin may be a feasible alternative 2.
  • Alternative treatments, such as tetracycline, erythromycin, or cephalothin, may be used for patients allergic to penicillin, although their efficacy for late syphilis is uncertain 3.

Confirmation of Cure

  • The cure is typically confirmed by monitoring the results of Venereal Disease Research Laboratory (VDRL) or other reagin tests, which should become negative or remain at very low titer following adequate therapy 3, 5, 4.
  • A fourfold decrease of VDRL titres is often used as an indicator of serological cure, which can be achieved within a median of 102 days after treatment initiation 5.
  • However, some patients may remain seropositive, a condition known as the "serofast state," and serologic response to treatment may be slower for latent syphilis 4.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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