Penicillin G: What You Need to Know

Penicillin G: What You Need to Know

Penicillin G, the trusty antibiotic, comes in with a needle jab or an IV drip. Let’s break it down for you:

Forms and Functions

  • Injections Only: Penicillin G benzathine and penicillin G procaine are strictly intramuscular.
  • Syphilis Savior: The benzathine form delivers a steady dose over 2-4 weeks—perfect for tackling syphilis or preventing rheumatic fever.
  • Versatile Warrior: Penicillin G fights a range of infections, from clostridial trouble to anthrax and respiratory woes.

Safety First

  • Pregnancy Pal: It’s a pregnancy category B buddy—safe during those expectant months.
  • Kidney Watch: Since it waltzes out through urine, dose adjustments are needed for renal patients.

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The Side Hustle: Adverse Effects

  • Common Troublemakers:
    • Nausea
    • Vomiting
    • Diarrhea
    • Abdominal pain
    • Rashes
  • Less Likely Guests:
    • Muscle spasms or pain
    • Fever and chills
    • Headaches
    • Rapid heart rate and breathing
    • Flushing
    • Low blood pressure
  • Allergic Drama: Immediate-onset hypersensitivity can lead to anaphylaxis.
  • Fashionably Late Reactions: Delayed-onset hypersensitivity (1-2 weeks in) may bring exfoliative dermatitis and serum sickness.
  • Mind the Nerves: Neurological side effects may pop up in renal cases.
  • Heavy Doses, Heavy Risks: Large intravenous doses can cause hemolytic anemia, neutropenia, and renal damage.
  • Tag-Team Trouble: Like any antibiotic, penicillin G might invite clostridium difficile diarrhea, thrush, or yeast infections.
  • Syphilis Surprise: Starting treatment? Watch out for the Jarisch-Herxheimer reaction—headache, fever, chills, sweats, joint and muscle pain, rapid heart rate, and dizziness within hours to a day.

Social Interactions

  • Birth Control Alert: Penicillin G might play spoiler with birth control pills. Double up on protection!
  • Probenecid Pals: Probenecid hangs out, decreases renal excretion, and boosts penicillin G levels. They’re practically inseparable.

Remember, penicillin G is like that reliable friend—sometimes a lifesaver, sometimes a party pooper! 🌟💉


  • Penicillin G: Antibiotic via injection or IV.
  • Forms: Intramuscular only (benzathine and procaine).
  • Uses: Treats various infections.
  • Safety: Safe during pregnancy.
  • Side Effects: Nausea, rashes, muscle pain.
  • Interactions: Watch birth control pills and probenecid.
  • Remember: Moderation and wise choices! 💉

This article reviewed by Dr. Jim Liu, MD and Ms. Deb Dooley, APRN.

There’s nothing more important than our good health – that’s our principal capital asset.

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