Up to a fifth of the general public is said to be allergic to penicillin. But penicillin allergies come and go – many patients manage to “outgrow” their allergies to this medicine.

Only about 5% of people with a faint history of penicillin allergy tend to be penicillin-allergic in the long run. This has significant implications, highlighting the need to debunk the Penicillin allergy label.

Patients with penicillin allergies are dealing with personal and public health challenges – not to mention significant financial implications.  When needed, these patients receive more broadspectrum antibiotics, placing them at risk for developing resistant bacteria such as the superbug Methicillin-resistant Staphylococcus aureus (MRSA).

Penicillin allergic patients are 69% more likely to develop these scary bacteria. They also have a 50% higher rate of surgical site infections. Hospital stays are between two to five days longer and you are at higher risk for readmission in 30 to 180 days.

Costs for Penicillin allergic patients are significantly higher for both inpatient and outpatient care.

How do I know if I am allergic to Penicillin?

The Basophil Activation Test, also known as a Cellular Allergen Stimulation Test (CAST) is commercially available for Penicillin Allergy testing in South Africa and is said to be 93% accurate. Patients are most likely to get an accurate result within a year of allergic reactions.

Unfortunately, if your CAST test is negative, it does not mean you do not have a penicillin allergy, especially if more than a year elapsed since your last allergic reaction. Up to 40% of patients with a negative test can still experience allergic reactions.

So what must I do for certainty?

If your CAST test is negative, it always is a good idea to obtain a referral to a medical practitioner that is experienced and equipped to do skin prick testing. If your skin prick test is negative, the Penicillin will be given to you either as a single dose or as a titrated dose. You will be observed for an hour afterwards.

If you have had an allergic reaction to Penicillin 10 years ago, or if you cannot even remember what happened when you were given Penicillin, chances are that you are not allergic to Penicillin anymore.

This is beneficial for your health and your pocket.

* Source: New England Journal of Medicine, available at https://www.nejm.org/doi/full/10.1056/NEJMra1807761

The purpose of this article is to raise awareness of allergies and the treatment options that are available for it. This article should by no means be used, or viewed, as a primary source for medical or other professional advice – please arrange for a personal consultation with your medical practitioner before taking any decisions that could affect the wellbeing of you or your loved ones. Read our medical disclaimer for more information.


Marinda McDonald

Dr Marinda McDonald has offered specialised treatments for allergies for most of her professional career. Read more about her on the home page of this website (allergydoc.co.za).

0 Comments

Leave a Reply

Your email address will not be published. Required fields are marked *