Penicillin G Benzathine Injection


Penicillin G benzathine injection is used to treat and prevent certain infections caused by bacteria. Penicillin G benzathine injection is in a class of antibiotics called penicillins. It works by killing bacteria that cause infections.

Antibiotics such as this injection will not work for colds, flu, or other viral infections. Taking antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.

Side Effects Of Penicillin G Benzathine Injection

Penicillin G benzathine injection may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • nausea
  • vomiting
  • pain, swelling, lump, bleeding or bruising in the area where the medication was injected

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately or get emergency medical treatment:

  • rash
  • hives
  • itching
  • difficulty breathing or swallowing
  • swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs
  • hoarseness
  • sore throat
  • chills
  • fever
  • headache
  • muscle or joint pain
  • weakness
  • fast heartbeat
  • severe diarrhea (watery or bloody stools) with or without fever and stomach cramps that may occur up to 2 months or more after your treatment
  • sudden onset of lower back pain, muscle weakness, numbness, and tingling
  • blue or black skin discoloration in the area where the medication was injected
  • skin blistering, peeling or shedding in the area where the medication was injected
  • numbness of the arm or leg in which the medication was injected

This injection may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

Warnings & Precautions

Before receiving penicillin G benzathine injection:

  • tell your doctor and pharmacist if you are allergic to penicillin G benzathine injection; other penicillin antibiotics; cephalosporin antibiotics such as cefaclor, cefadroxil, cefazolin (Ancef, Kefzol), cefditoren (Spectracef), cefepime (Maxipime), cefixime (Suprax), cefotaxime (Claforan), cefoxitin, cefpodoxime, cefprozil, ceftazidime (Fortaz, Tazicef), ceftibuten (Cedax), ceftriaxone (Rocephin), cefuroxime (Ceftin, Zinacef), and cephalexin (Keflex); or any other medications. Ask your doctor or pharmacist if you are not sure if a medication you are allergic to belongs to one of these groups of medications. Also tell your doctor if you are allergic to any of the ingredients in penicillin G benzathine injection. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention: probenecid (Probalan) and tetracycline (Achromycin). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have or have ever had asthma, allergies, hay fever, hives, or kidney disease.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while receiving penicillin G benzathine injection, call your doctor.

Penicillin G Benzathine Injection Dosage

Penicillin G benzathine injection comes as a suspension (liquid) in a prefilled syringe to inject into the muscles of the buttocks or thigh by a doctor or nurse in a medical facility. The injection may be given as a single dose. When used to treat or prevent certain serious infections, additional doses may be given at least 7 days apart. Ask your doctor if you have any questions about how many doses you will need or when you will receive them.

You should begin to feel better during the first few days of treatment with penicillin G benzathine injection. If your symptoms do not improve or get worse, call your doctor.

If your doctor has told you that you will need additional doses of penicillin G benzathine injection, make sure to keep all appointments to receive your doses on schedule even if you are feeling better. If you stop using penicillin G benzathine injection too soon or skip doses, your infection may not be completely treated and the bacteria may become resistant to antibiotics.


Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body’s response to penicillin G benzathine injection.

Ask your pharmacist any questions you have about penicillin G benzathine injection.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.