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How do I know if I am allergic to penicillin?
Around 10–20% of people believe, or have been told, that they are allergic to penicillin. However, fewer than 1 in 10 of those labelled as allergic actually have a true penicillin allergy.
There are several reasons why someone might be incorrectly labelled as allergic:
- Side effects mistaken for allergy: Common reactions such as nausea, diarrhoea, stomach discomfort, or thrush can occur with penicillin, but these are side effects – not allergies.
- Symptoms caused by the illness itself: Sometimes, a illness which you were taking penicillin for caused symptoms, like a rash, which were mistaken for an allergy.
- Childhood experiences: Many people were advised to avoid penicillin due to a reaction in childhood, but these labels often persist without proper reassessment.
Once the penicillin allergy label is on your medical records, it can be very difficult to remove. A penicillin allergy test is the safest way to find out if you are really allergic to penicillin.
Why is it important to have a penicillin allergy test?
There are lots of different types of antibiotics called ‘penicillins’ that are useful for treating lots of different infections, including some that can be life-threatening. These types include co-amoxiclav (Augmentin), penicillin V, ampicillin, flucloxacillin, amoxicillin and many others.
Penicillins are very safe to take and it is important that your medical record is correct to make sure you get the best care when you are unwell.
If you’re wrongly labelled as allergic to penicillin, you won’t be given it, even when it might be the best medicine for you.
Instead, you might be given alternative antibiotics that:
- May not work as well
- Can increase the risk of side effects
- Might disrupt the balance of healthy bacteria in your body, leading to issues like new infections
- Increase your resistance to antibiotics, which may prevent them from working effectively in the future
We understand that undergoing this type of test can feel worrying. However, it’s important to know that penicillin allergy testing is carried out safely in many centres around the world and has an excellent safety record.
The risk of a serious allergic reaction during testing is very low, and the process is carefully managed by trained professionals.
If a test shows that you are not allergic to a penicillin we can remove this incorrect label and you will be able to take penicillin when you need it.
What does the penicillin allergy testing involve?
Your medical team will begin by asking you some questions about your penicillin allergy label. You’ll only be offered this test if they believe the label may be incorrect and that it’s safe for you to proceed.
The test involves taking a penicillin antibiotic tablet while in hospital. You’ll be closely monitored for one hour, including regular checks of your pulse and blood pressure.
- If you do not experience an allergic reaction, your GP will be asked to remove the penicillin allergy label from your medical record.
- If the test confirms that you are allergic to penicillin, your GP will be asked to update your record to reflect this.
Are there any risks to having the test?
This test is considered very safe and is carried out under close supervision by trained medical professionals.
While there is a small possibility of experiencing side effects such as feeling sick or an allergic reaction, serious reactions are extremely rare.
If a serious allergic reaction does occur, your medical team will be on hand to provide immediate treatment and support.
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