Stage of syphilis | Treatment |
Primary/secondary/early latent | Penicillin G benzathine (Bicillin L-A) 2.4 million units IM in a single dose (usually administered as 1.2 million units in each buttock)* |
Late latent/tertiary/unknown duration | Penicillin G benzathine (Bicillin L-A) 2.4 million units IM once weekly (usually administered as 1.2 million units in each buttock) for 3 weeks (7.2 million units total dose)¶ |
Neurosyphilis (including ocular syphilis)Δ | Aqueous crystalline penicillin G (intravenous) 18 to 24 million units per day, administered as 3 to 4 million units IV every 4 hours or as a continuous infusion over 24 hours for 10 to 14 days or Penicillin G procaine 2.4 million units IM once daily (usually administered as 1.2 million units in each buttock) plus probenecid 500 mg PO 4 times daily, both for 10 to 14 days |
Post-exposure prophylaxis | Penicillin G benzathine (Bicillin L-A) 2.4 million units IM in a single dose (usually administered as 1.2 million units in each buttock) |
IM: intramuscular; IV: intravenous; PO: oral.
* Some clinicians administer an additional dose of penicillin G benzathine 2.4 million units one week after the first dose to patients with primary, secondary, or early latent disease, based in part on evidence of efficacy and on pharmacokinetic data of altered penicillin levels in pregnant people. There is no harm to giving a second dose, but it has not been recommended in guidelines from national organizations because the value of a second dose has not been evaluated in a randomized trial.
If serologic failure is detected at follow-up and additional follow-up cannot be assured, consider retreating with penicillin G benzathine 2.4 million units IM once weekly for 3 weeks. Prompt cerebrospinal fluid examination is recommended.
¶ If a dose is missed for more than 14 days, then the full 3-dose course of therapy should be restarted.
Δ Penicillin G benzathine 2.4 million units IM once per week for up to 3 weeks may be administered after completion of IV penicillin G treatment to provide a comparable total duration of therapy as latent syphilis.