Benzyl penicillin

By Medically reviewed by Hello Doktor Medical Panel


What is benzyl penicillin used for?

Benzyl penicillin is commonly used for treatment bacterial infections of:

  • The middle ear (otitis media)
  • The throat
  • The nasal passages or sinuses
  • The skin and soft tissue (e.g., cellulitis)
  • Pneumonia
  • Meningitis
  • The blood (septicemia)
  • The bones (osteomyelitis)
  • Tetanus
  • Lyme disease
  • Leptospirosis (Weil’s disease)
  • Diphtheria
  • Anthrax
  • Gas gangrene
  • Inflammation of the lining of the heart cavity and heart valves due to infection with the bacterium streptococcus (endocarditis)

Benzyl penicillin may be prescribed for other uses; ask your doctor or pharmacist for more information.

How should I take benzyl penicillin?

Benzyl penicillin is given by both intramuscular and intravenous injection. Ask your health care provider any questions you may have about how to use benzyl penicillin.

How do I store benzyl penicillin?

Benzyl penicillin is best stored in the refrigerator. To prevent drug damage, do not freeze. There may be different brands of benzyl penicillin that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush benzyl penicillin down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard benzyl penicillin when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using benzyl penicillin?

Consult with your doctor or pharmacist, if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of benzyl penicillin or other medications such as other antibiotics (in particular other penicillin, cephalosporins or beta-lactams).
  • You have any other illnesses, disorders, or medical conditions, such as stomach or bowel problems, liver problems or unexplained abnormal liver function tests, or kidney problems.
  • You have any other types of allergies, such as to foods, dyes, preservatives, or animals.

Is it safe during pregnancy or breastfeeding?


Benzyl penicillin sodium has been taken by a large number of pregnant women and women of childbearing age without an increase in malformations or other direct or indirect harmful effects on the fetus having been observed.


Excreted into breast milk, caution advised.

Always consult your health care provider prior to using benzyl penicillin if you are pregnant, breastfeeding.

Side effects

What side effects can occur from benzyl penicillin?

If you experience any of these symptoms tell your doctor immediately, including:

  • Allergic reaction includes itching, hives, fever (high temperature)
  • Joint pains
  • Swelling of the tongue, throat or face
  • Difficulty breathing
  • Collapse

Tell your doctor if you think you have developed any new infections either during or after treatment with this medicine, including overgrowth of non-susceptible organisms such as the yeast Candida, which may cause infection such as thrush.

Some rare side effects include:

  • Inflammation of the large intestine (colitis)
  • Convulsions
  • Blood disorders

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with benzyl penicillin?

Benzyl penicillin may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Some drugs may interact with benzyl penicillin including:

  • Methotrexate
  • Probenecid
  • Oral contraceptives
  • Allopurinol or sulfinpyrazone – treatments for gout
  • Neomycin – an antibiotic
  • Anti-coagulants – medicines that prevent blood clots
  • Oral typhoid vaccine

Benzyl penicillin may interfere with:

  • Urinary glucose test
  • Coomb’s tests
  • Tests for urinary or serum proteins
  • Tests which use bacteria e.g. Guthrie test

Does food or alcohol interact with benzyl penicillin?

Benzyl penicillin may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with benzyl penicillin?

Benzyl penicillin may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have, especially:


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this medication.

What is the dose of benzyl penicillin for an adult?

600 to 3,600 mg daily is divided into 4 to 6 doses, depending on the indication. Higher doses (up to 14.4 g/day in divided doses) may be given in serious infections such as adult meningitis by the intravenous route.

In bacterial endocarditis, 7.2 to 12 g or more may be given daily in divided doses by the intravenous route, often by infusion.

Doses up to 43.2 g per day may be necessary for patients with rapidly spreading gas gangrene.

High doses should be administered by intravenous injection or infusion, with intravenous doses in excess of 1.2g being given slowly, taking at least one minute for each 300 mg to avoid high levels causing irritation of the central nervous system and/or electrolyte imbalance.

High dosage of benzyl penicillin sodium may result in hypernatraemia and hypokalaemia unless the sodium content is taken into account.

For the prevention of Group B Streptococcal disease of the newborn, a 3 g loading dose should be given to the mother initially, followed by 1.5 g every 4 hours until delivery.

Meningococcal disease in adults and children over 12 years are 2.4 g every 4 hours.

Suspected meningococcal disease in adults and children over 10 years are 1,200 mg.

What is the dose of benzyl penicillin for a child?

Children aged 1 month to 12 years, 100 mg/kg/day is in 4 divided doses; not exceeding 4 g/day.

Infants 1-4 weeks, 75 mg/kg/day is in 3 divided doses.

Newborn infants, 50 mg/kg/day is in 2 divided doses.

Meningococcal disease Children 1 month to 12 years:

180-300 mg/kg/day is in 4-6 divided doses, not exceeding 12 g/day.

Infants 1-4 weeks, 150 mg/kg/day is in 3 divided doses.

Newborn infants, 100 mg/kg/day is in 2 divided doses.

Suspected meningococcal disease:

If meningococcal disease is suspected general practitioners should give a single dose of benzyl penicillin sodium, before transferring the patient to hospital, as follows:

  • Children 1-9 years: 600 mg intravenous injection (or Intramuscular Injection)
  • Children under 1 year: 300 mg intravenous injection (or intramuscular injection)

Premature babies and neonates:

Dosing should not be more frequent than every 8 or 12 hours in this age group, since renal clearance is reduced at this age and the mean half-life of benzyl penicillin may be as long as 3 hours.

Since infants have been found to develop severe local reactions to intramuscular injections, intravenous treatment should preferably be used.

How is benzyl penicillin available?

Benzyl Penicillin is available in the following dosage forms and strengths:

  • Each vial contains: benzyl penicillin sodium 600mg and 1200mg powder for injection.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

It is also important to carry a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking with you in case of emergencies.

What should I do if I miss a dose?

If you miss a dose of Benzyl Penicillin, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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Review Date: December 29, 2016 | Last Modified: December 19, 2019

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