Consumer medicine information


Benzylpenicillin (as benzylpenicillin sodium) Powder for Injection

Consumer Medicine Information

What is in this leaflet

This leaflet answers some common questions about BENPEN™.

It does not contain all the available information.

It does not take the place of talking to your doctor and pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risks of you taking BENPEN™ against the benefits this medicine is expected to have for you.

If you have any concerns about taking this medicine, ask your doctor or pharmacist.

Keep this leaflet. You may need to read it again.

What BENPEN™ is used for

BENPEN™ is an antibiotic used to treat some infections in different parts of the body caused by bacteria.

BENPEN™ may also be used to prevent infections before, during and after surgery.

BENPEN™ will not work against infections caused by viruses, such as colds or the flu.

BENPEN™ is an antibiotic that belongs to a group of medicines called penicillins. These antibiotics work by killing the bacteria that are causing your infection.

Your doctor may have prescribed BENPEN™ for another reason. Ask your doctor why BENPEN™ has been prescribed for you.

This medicine is available only with a doctors prescription.

There is no evidence that BENPEN™ is addictive.

Before you are given BENPEN™

When you must not be given it

Do not use BENPEN™ if:

  • you have an allergy to BENPEN™ or other penicillins.
  • Some of the symptoms of an allergic reaction may include skin rash, itching and difficult breathing.
  • you have had an allergic reaction to cephalosporins.
  • You may have an increased chance of being allergic to BENPEN™ if you are allergic to cephalosporins.
  • the packaging is torn or shows signs of tampering.
  • the expiry date printed on the pack or vial, has passed. If you take this medicine after the expiry date has passed, it may not work.

If you are not sure whether you should be given BENPEN™, talk to your doctor.

Before you are given it

Tell your doctor if:

  1. you have an allergy to BENPEN™ or any other penicillin.
  2. you have had any type of allergic reaction to cephalosporin medicines

You may have an increased chance of being allergic to BENPEN™ if you are allergic to cephalosporins.

  1. you have any allergies to any other medicines or any other substances, such as foods, preservatives or dyes. This may include medicines that you buy without a prescription from your pharmacy, supermarket or health food shop.
  2. you have or have ever had any other health problems/medical conditions, including asthma, kidney or liver disease.
  3. you are pregnant or intend to become pregnant. Your doctor will discuss the risks and benefits of using BENPEN™ during pregnancy.
  4. you are breast-feeding or plan to breast-feed. Your doctor will discuss the risks and benefits of using BENPEN™ when breast-feeding.

If you have not told your doctor about any of the above, tell them before you are given BENPEN™.

Taking other medicines

Tell your doctor if you are taking any other medicines, including medicines that you buy without a prescription from your pharmacy, supermarket or health food shop. Some medicines may interfere with BENPEN™. These include probenecid (Benemid) and some antibiotics eg. tetracyclines, erythromycin and chloramphenicol. These medicines may affect BENPEN™ and how well it works. You may need different amounts of your medicine, or you may need to take different medicines.

Some antibiotics may decrease the effectiveness of some birth control pills. Talk to your doctor about the need for an additional method of contraception while taking BENPEN™.

Your doctor or pharmacist has more information on medicines to be careful with or avoid while taking BENPEN™.

How BENPEN™ is given

BENPEN™ may be given in two ways:

  • as a slow injection into a vein
  • as a deep injection into a large muscle

BENPEN™ must only be given by a doctor or nurse.

Your doctor will decide what dose and for how long you will receive BENPEN™. This depends on your infection and other factors, such as your weight. For most infections, BENPEN™ is usually given in divided doses throughout the day. Sometimes only a single dose of BENPEN™ is required for the treatment and prevention of certain infections.

Each BENPEN™ vial is used for one dose in one patient only. Any remaining contents must be discarded after each dose to reduce microbiological contamination.

If you have too much BENPEN™ (Overdose)

This rarely happens as BENPEN™ is administered under the care of a highly trained doctor. However, if you are given too much BENPEN™, you may experience some of the effects listed under ‘Side Effects’ below.

Your doctor has information on how to recognise and treat an overdose. Ask your doctor if you have any concerns.

After you have been given BENPEN™

Things you must do

If the symptoms of your infection do not improve within a few days, or if they become worse, tell your doctor.

If you develop itching with swelling or skin rash or difficulty breathing after you have been given BENPEN™, contact your doctor immediately as these are symptoms of an allergic reaction.

If you get severe diarrhoea tell your doctor or pharmacist immediately. Do this even if it occurs several weeks after BENPEN™ has been stopped. Diarrhoea may mean that you have a serious condition affecting your bowel. You may need urgent medical care. Do not take any diarrhoea medicine without first checking with your doctor.

If you get a sore white mouth or tongue after you have been given BENPEN™, tell your doctor. Also tell your doctor if you get vaginal itching or discharge. This may mean you have a fungal infection called thrush. Sometimes the use of BENPEN™ allows fungi to grow and the above symptoms to occur. BENPEN™ does not work against fungi.

If you become pregnant while you are taking BENPEN™ tell your doctor.

If you are about to start taking any new medicine, tell your doctor and pharmacist that you have been given BENPEN™.

If you have to have any tests tell your doctor you have been given BENPEN™. BENPEN™ may affect the results of some tests.

Tell any doctor, dentist or pharmacist who is treating you that you have been given BENPEN™.

Things to be careful of

Be careful driving or operating machinery until you know how BENPEN™ affects you. BENPEN™ generally does not cause any problems with your ability to drive a car or operate machinery. However, as with many other medicines, BENPEN™ may cause dizziness, drowsiness, and tiredness in some people.

Side Effects

Tell your doctor as soon as possible if you have any problems while taking BENPEN™, even if you do not think the problems are connected with the medicine or are not listed in this leaflet. Like other medicines, BENPEN™ can cause some side effects. If they occur, most are likely to be minor and temporary. However, some may be serious and need medical attention.

Ask your doctor or pharmacist to answer any questions you may have.

While being given BENPEN™

Tell your doctor IMMEDIATELY or go to casualty at your nearest hospital if you notice any of the following:

  • A severe rash
  • Wheezing
  • Palpitations
  • Feeling faint

These are very serious side effects. If you have any of these side effects, you may be having a serious allergic reaction to BENPEN™.

Tell your doctor if you notice any of the following:

  • oral thrush – white, furry, sore tongue and mouth
  • vaginal thrush – sore and itchy vagina and/or discharge
  • a mild rash

Other side effects not listed above may also occur in some patients. These include very rare cases of brain, blood and kidney disease.

After finishing BENPEN™

An illness consisting of a rash, swollen glands, joint pains and fever may occur about a week after the treatment.

Tell your doctor IMMEDIATELY if you notice any of the following side effects, particularly if they occur several weeks after finishing treatment with BENPEN™:

  • severe abdominal cramps or stomach cramps
  • watery and severe diarrhoea, which may also be bloody
  • fever, in combination with one or both of the above

These are rare but serious side effects. BENPEN™ can change bacteria (which are normally present in the bowel and normally harmless) to multiply and therefore cause the above symptoms. You may need urgent medical attention. However, this side effect is rare. Do not take any diarrhoea medicine without first checking with your doctor.

Tell your doctor if you notice any other side effects.

After using BENPEN™


BENPEN™ will be stored in the pharmacy or on the ward. The powder for injection is kept protected from light in a cool dry place where the temperature stays below 25°C.

Do not use BENPEN™ after the expiry date on the label.

MEDICINE description

What it looks like

BENPEN™ is a white to off-white powder that has to be dissolved in water before it is injected.


Benzylpenicillin (as benzylpenicillin sodium), 600mg, 1.2g or 3g.

BENPEN™ does not contain gluten, lactose, sucrose, tartrazine or any other azo dyes.

The Australian Registration Numbers are:
600mg AUST R 10329
1.2g AUST R 10326
3g AUST R 10327


CSL Limited ABN 99 051 588 348
45 Poplar Road
Parkville 3052 Victoria

Date of preparation: June 1999

Published by MIMS November 2003