What is penicillin?

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

Before penicillin was discovered in 1928 and later made into an antibiotic by a team led by scientist Howard Florey, having a simple scratch could lead to an infection that could kill. Using penicillin and other antibiotics has saved many thousands of lives.

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

• amoxicillin (brand names Alphamox, Amoxil, Cilamox, Ibiamox, Fisamox)
• amoxicillin/clavulonic acid (brand name: Augmentin)
• ampicillin (brand names Agpen, Alphacyn, Ampicyn, Austrapen, Ibimicyn, Penamp)
• benzylpenicillin (brand name BenPen)
• benzathine benzylpenicillin (brand name Bicillin-LA)
• dicloxacillin (brand names Dicloxsig, Distaph)
• flucloxacillin (brand names Flubiclox, Flucil, Flopen, Flucil, Staphylex)
• phenoxymethylpenicillin (Penicillin V) (brand names Aspecillin, Cilicaine VK, Cilicaine V, Cilopen)
• piperacillin (brand name Tazopip, PiperTaz, Tazocin, Piptaz Procaine benzylpenicillin Cilicaine)

What is penicillin used for?

Penicillin works on many types of bacterial infection, unless the infection is resistant 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
• other bacterial infections

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

Are there side effects to penicillin?

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

• stomachache
• diarrhoea
• nausea
• skin rashes and 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 effects of penicillin are rare and include:

• difficulty breathing due to a severe allergic reaction (anaphylaxis)
• sudden and
• 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).

Penicillin allergy

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

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 start swelling, you might have penicillin anaphylaxis.

Tell your doctor, dentist and all other health providers if you have had any symptoms of penicillin allergy. Your doctor might run further tests to confirm the severity of your allergy.

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

You can read more about managing medication allergy on the ASCIA website.

Resources and support

For more information about penicillin allergy, contact the Australasian Society of Clinical Immunology and Allergy (ASCIA).

Visit NPS MedicineWise for information about penicillin and other medicines. You can also call the NPS Medicines Line on 1300 633 424.

If you are experiencing any side effects and are not sure what to do, call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria).