Penicillin allergy information sheet
Penicillin allergy information sheet
Who is this leaflet for?
This leaflet is for anyone who has been told they have a penicillin allergy or has it recorded in their medical records.
What is penicillin?
Penicillin is an important antibiotic used to treat many common infections. It is often the first choice for treatment of common infections. The term penicillin is also used to describe a group of similar antibiotics such as penicillin, amoxicillin, flucloxacillin and co-amoxiclav.
What is a penicillin allergy?
A penicillin allergy is when your immune system reacts to penicillin. Most allergic reactions are mild and may include symptoms such as a rash or itching. In very rare cases, a serious reaction called anaphylaxis can happen. Anaphylaxis can cause difficulty breathing, throat swelling and collapse.
Is it a penicillin allergy or side effect?
Some symptoms that people experience after taking penicillin are side effects rather than an allergy. Common side effects include feeling sick or having an upset stomach or diarrhoea.
Having side effects does not mean that you are allergic to penicillin and does not always mean you need to avoid penicillin in the future. Your healthcare team can discuss this with you.
How do I know if I am allergic to penicillin?
Many people (about 1 in 10) who have a penicillin allergy recorded in their medical records are not actually allergic to penicillin. By reviewing your medical history and discussing any previous reactions, we can assess whether you are likely to be allergic to penicillin and decide the safest next step.
Will I be tested for penicillin allergy?
Once we review your medical records and have more details about the reaction you had before to penicillin we will talk to you about what will happen next.
- In some cases, reviewing your medical history and previous reaction provide enough information for us to be confident that the penicillin allergy label is no longer needed. The allergy label may then be removed without any further testing.
- If the reaction you had suggests that you do have a penicillin allergy, the allergy label will remain on your records.
- If it is unclear whether you have a penicillin allergy or not, we may offer you further testing. This will only be offered if it is considered safe and appropriate for you.
Do I have to agree to the penicillin allergy check?
No. It is completely your choice.
If you decide not to take part your care will not change.
What if I change my mind later?
If you decide you would like a penicillin allergy assessment in the future, please speak to your GP or healthcare team.
Questions?
Please speak to a member of your healthcare team if you have any questions about the penicillin allergy test, your results and what that means for you.
See the downloadable version of the penicillin allergy information sheet.
Scottish Antimicrobial Prescribing Group (SAPG) | August 2026 for review Aug 2029
Content update October 2026