Penicillins and penicillin allergy

Key information about penicillins and penicillin allergy

  • A penicillin allergy is a rare and severe reaction of your immune system to a penicillin-containing antibiotic. 
  • Most people who think they have a penicillin allergy do not. If you think you have a penicillin allergy, talk with your doctor, pharmacist or nurse.
  • Read about penicillin allergies and what to do if you are allergic to penicillin.
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Penicillins are a group of antibiotic medicines commonly used to treat infections (eg, urinary tract, skin and chest infections) that are caused by bacteria.

Penicillins are the safest and most effective antibiotics for many infections. When compared to other groups of antibiotics, they cause fewer problems, eg, side effects or antibiotic resistance.  They don't work for infections caused by viruses (eg, colds, flu or COVID-19) – no antibiotic does.

Examples of penicillin antibiotics available in Aotearoa New Zealand

Penicillins available in Aotearoa New Zealand Also called
  • Amoxil®
  • Alphamox®
Amoxicillin + clavulanic acid
  • Augmentin ®
  • Curam®
  • m-Amoxiclav®
Benzathine penicillin
  • Bicillin LA®
  • Flucloxacillin (AFT)®
  • Cilicaine VK®
  • Phenoxymethylpenicillin (AFT)®
Piperacillin with tazobactam
  • Pip Taz (AFT)®
  • Piperacillin/Tazobactam (Kabi)®
Procaine benzylpenicillin
  •  Cilicaine®
Pivmecillinam hydrochloride
  • Selexid®

A penicillin allergy is a rare and severe reaction of your immune system to a penicillin-containing antibiotic. Severe penicillin allergy is also called a true penicillin allergy.

Signs and symptoms of severe penicillin allergy include anaphylaxis, (an immediate life-threatening reaction), an itchy rash, difficulty breathing, and swollen lips or tongue. These usually happen within 60 minutes of taking a dose. 

True penicillin allergy is rare – fewer than 5 out of 10,000 people are allergic to penicillin. Reactions like nausea (feeling sick), diarrhoea (runny poo) or thrush often occur with antibiotics but are side effects not allergies. Sometimes these symptoms could be from your infection. Side effects are not nice and they usually pass once you finish your antibiotics. Read more about medicines and side effects.


Image credit: Healthify He Puna Waiora

If you think you have a penicillin allergy, talk with your doctor, pharmacist or nurse.

  • 1 out of 2 adults (half) can have their penicillin allergy label removed from their medical record after their healthcare team has asked some questions about the allergy and their medical history.
  • Sometimes, further tests (eg, giving a very small test dose of penicillin under medical supervision) might be needed to work out if you have a true penicillin allergy.
  • If you are one of the few people who have a true penicillin allergy, your healthcare team will help keep you safe. This will include making sure your online clinical records are accurate and using non penicillin containing antibiotics when you need treatment.

There are many antibiotics that don't contain penicillin. These can be used if you have a true penicillin allergy.  

If you have an infection that needs antibiotics, it's important to have the most effective antibiotic to treat it. If you can take penicillin it will widen the range of antibiotics your doctor can choose from when deciding what's the best treatment for you. So don’t limit your treatment choices – find out for sure whether you are allergic to penicillin. 

Did you know that you can report a medicine side effect to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product.(external link)


  1. Challenge your penicillin allergy(external link) New Zealand Antimicrobial Stewardship & Infection Pharmacist Expert Group (NAMSIPEG)
  2. Penicillin allergy FAQ(external link) American Academy of Allergy Asthma and Immunology, US, 2020
  3. Penicillin allergy initiative(external link) Pharmaceutical Society of NZ, 2021

The content on this page will be of most use to clinicians, such as nurses, doctors, pharmacists, specialists and other healthcare providers.


Penicillin allergy resources for health workers - Pharmaceutical Society of NZ, 2021

Information bulletin about antimicrobial resistance and World Antimicrobial Awareness Week - Canterbury DHB, Te Poari Hauora ō Waitaha, 2021


Challenge your penicillin allergy
Information sheet for consumers
PSNZ, 2021

Challenge your penicillin allergy
Poster for consumers
PSNZ, 2021

5 questions to ask about your medications
Health Quality and Safety Commission, NZ, 2019

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Stephanie Yee, Pharmacist, Auckland

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