How is primary syphilis treated?

The recommended treatment for primary syphilis is benzathine penicillin G, 2.4 million units in a single intramuscular (IM) dose or procaine penicillin, 600,000 units IM daily for 10 to 14 days. Nonpregnant patients who are allergic to penicillin can be treated with either doxycycline (100 mg orally two times per day for 14 days), tetracycline (500 mg orally four times per day for 14 days), or ceftriaxone (125 mg IM every day for 10 days, 250 mg IM every other day, or 1000 mg IM for 8 to 10 days).

Treatment failures have been reported with all regimens, and patients should have follow-up serologic titers at 3, 6, 12, and 24 months to ensure a fourfold decline in titers. Failure of non-treponemal antibody titers to fall fourfold within 6 months of treatment can be considered a probable treatment failure. Patients need to be reported to the proper public health agency to ensure tracking of known sexual partners.

Centers for Disease Control and Prevention: Sexually transmitted disease guidelines 2006, MMWR 55:22–33, 2006.