What is penicillin?

Penicillin is both the name of a single antibiotic and the name of a widely used group of antibiotic medicines. Using penicillin and other antibiotics has saved many people’s lives.

Penicillin is used to treat infections caused by certain types of bacteria. It does not work on viral infections (such as colds and flu).

Penicillin works on many types of bacterial infections, but not if the bacteria is resistant (not susceptible) to it.

Your doctor might prescribe you a type of penicillin if you have a:

• skin infection
• dental infection
• ear infection
• an infection of the nose, throat or lungs
• urinary tract infection (UTI)

Penicillin may also be prescribed for other types of bacterial infections.

Tell your doctor if you have ever had an allergic reaction to any antibiotics in the past.

How does penicillin work?

Different antibiotics work in different ways to kill bacteria or stop bacteria from spreading. Penicillin works by breaking down the bacteria’s cell walls. This weakens the bacteria and helps the body’s natural immune system to fight the infection.

What types of penicillin might I be prescribed?

Penicillin is both the name of a single antibiotic and the name of a group of antibiotics. Other types of penicillin include:

• amoxicillin
• amoxicillin/clavulanic acid
• ampicillin
• benzylpenicillin
• benzathine benzylpenicillin
• dicloxacillin
• flucloxacillin
• phenoxymethylpenicillin (Penicillin V)
• piperacillin

What should I do if I cannot get my antibiotics?

Currently, there is a shortage of some antibiotics in Australia, including amoxicillin and cefalexin.

If you cannot get the medicine that you need, speak to your pharmacist or doctor. They can advise on alternatives. For more information, visit Therapeutic Goods Administration (TGA).

Does penicillin have any side effects of risks associated with it?

All medicines have side effects, as well as benefits. The common side effects of penicillin are usually mild. You might experience:

• stomach ache
• diarrhoea
• nausea
• skin rashes and/or hives

Less common side effects include:

• shortness of breath or irregular breathing
• abdominal cramps, spasms, tenderness or pain
• vaginal itching and discharge, due to either a yeast infection or bacterial vaginosis

Serious side effect of penicillin

Serious side effects of penicillin are rare and include:

• difficulty breathing due to a severe allergic reaction (anaphylaxis)
• seizures

Call triple zero (000) and ask for an ambulance or ask someone to take you to the nearest emergency department immediately if you experience any serious side effects after taking penicillin (such as anaphylaxis). If you have an adrenaline auto-injector, use it and then call an ambulance.

When should I see my doctor?

See your doctor if you are taking penicillin and develop non-urgent signs of a penicillin allergy. Call triple zero (000) and ask for an ambulance if you develop serious side effect of penicillin.

See your doctor if you have signs of infection that may need treatment with penicillin. Signs and symptoms include:

• fever
• earache
• cough
• pus or weeping sore on your skin
• pain or swelling around a tooth

Penicillin allergy

About 1 in 100 people has an allergy to penicillin, and about 1 in 3,000 people has a life-threatening allergic reaction to penicillin. If you are allergic to one type of penicillin, you will also likely be allergic to other types too. Always ask your doctor if you are not sure about your allergies.

If you get skin rashes, hives or mild wheezing after taking this medicine, you might have a penicillin allergy.

If you have serious trouble breathing (heavy wheezing) or if your face starts swelling, you might have penicillin anaphylaxis.

Your doctor might refer you for tests to confirm your allergy. Tell your doctor, dentist and all other health providers if you have ever had any symptoms of penicillin allergy.

If you are diagnosed with an allergy to penicillin, you will need to avoid it in future. Always tell medical staff about the allergy. Make sure it is recorded on your My Health Record, in your doctor's medical records and in any hospital records. You should also wear a medical alert bracelet.

Are there any alternatives to this medicine?

There are other types of antibiotics that you can take if you are allergic to penicillin or if penicillin isn’t available. Ask your doctor which other medicines would be appropriate for your condition.

Resources and support

For more information about penicillin allergy, see the Australasian Society of Clinical Immunology and Allergy (ASCIA). They also provide a Frequently Asked Questions (FAQ) sheet that explains what a penicillin allergy is, testing and its benefits.

You can call 1300 MEDICINE (1300 633 424) for information about penicillin and other medicines.

Call healthdirect on 1800 022 222 at any time to speak to a registered nurse (known as NURSE-ON-CALL in Victoria) for more information and advice.