From the Guidelines
Doxycycline is the preferred treatment for syphilis in patients with a penicillin allergy.
Treatment Options
- Doxycycline: 100 mg orally twice daily for 14 days for early syphilis 1 and 28 days for late latent syphilis or latent syphilis of unknown duration 1
- Tetracycline: 500 mg orally four times daily for 14 days for early syphilis 1 and 28 days for late latent syphilis or latent syphilis of unknown duration 1
- Ceftriaxone: 1 g daily either IM or IV for 10–14 days for early syphilis, although the optimal dose and duration have not been defined 1
- Azithromycin: a single 2-g oral dose for early syphilis, but its use should be with caution due to resistance and treatment failures 1
Important Considerations
- Close follow-up of persons receiving alternative therapies is essential 1
- Patients with a penicillin allergy whose compliance with therapy or follow-up cannot be ensured should be desensitized and treated with benzathine penicillin 1
- The efficacy of these alternative regimens in HIV-infected persons has not been well studied and should be used with caution 1
From the Research
Treatment Options for Syphilis in Patients with Penicillin Allergy
- Patients with a penicillin allergy may require alternative treatments for syphilis, as penicillin is the first-line regimen for treating the disease 2, 3, 4.
- Ceftriaxone has been shown to be as effective as penicillin in treating early syphilis, with similar serological response rates and treatment failure rates 3, 4.
- Doxycycline is also an acceptable alternative option for treating early and late latent syphilis if penicillin cannot be used 5, 6.
- Other options, such as erythromycin, minocycline, and tetracycline, may also be considered, but their efficacy is not as well established as ceftriaxone and doxycycline 4.
Considerations for Specific Patient Populations
- In immunocompromised patients, such as those with HIV, alternative treatments like doxycycline may be effective in treating syphilis 5.
- Pregnant women with penicillin allergies require careful consideration, as missed doses of penicillin are not acceptable in this population 6.
- Patients with neurological signs or symptoms consistent with neurosyphilis, or those with tertiary syphilis, may require a cerebrospinal fluid examination to diagnose neurosyphilis 6.
Gaps in Current Knowledge
- More research is needed to determine the efficacy and safety of alternative treatments for syphilis, particularly in patients with penicillin allergies 3, 4, 6.
- Large-scale, high-quality, double-blind trials are necessary to establish the optimal treatment regimens for syphilis in patients with penicillin allergies 4.