About benzathine benzylpenicillin
Long-acting penicillin antibiotic
Used for
- Treats certain bacterial infections, including strep throat and syphilis
- Prevents recurrent rheumatic fever
Usual adult dose
Varies by infection; syphilis is commonly treated with 2.4 million units injected once. Rheumatic fever prevention is usually 1.2 million units every 3–4 weeks.
Usual dose in children
Varies by infection and weight. Syphilis treatment is commonly 50,000 units/kg injected once, up to 2.4 million units.
Common side effects
- Injection-site pain or swelling
- Nausea or diarrhea
- Rash or allergic reactions
- Rare severe allergic reaction
Important warnings
- Given by deep muscle injection only; never inject into a vein
- Avoid with serious penicillin allergy
- Seek urgent care for breathing difficulty or facial swelling
- Use only for infections caused by susceptible bacteria
Pregnancy
Generally considered appropriate when needed; penicillin is commonly used during pregnancy, including for syphilis.
Breastfeeding
Generally compatible with breastfeeding; small amounts may enter milk and rarely affect the infant’s digestion or cause rash.
Interactions
- Probenecid can increase penicillin levels
- Methotrexate toxicity may increase
- May affect live oral typhoid vaccine effectiveness
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.