Explaining a false penicillin-allergy label and the delabelling pathway — OSCE

Candidate instructions (8-minute station)

You are the paediatric registrar in the clinic. A 6-year-old girl has community-acquired pneumonia and needs amoxicillin. She has carried a "penicillin allergy" label since age 2, when she developed a widespread maculopapular rash on day 5 of amoxicillin given for a viral illness; there was no swelling, breathing difficulty, blistering or mucosal involvement, and the label has never been evaluated. [3]

Your tasks are: [10]

1. Explain to the parent that the penicillin-allergy label is most likely false, and why, in plain language. [3]
2. Outline the safe delabelling pathway — a structured history, a risk check (PEN-FAST), and a supervised oral amoxicillin challenge. [2]
3. Explain the benefit of removing the label: restoring first-line penicillin and avoiding broader-spectrum, more problematic antibiotics. [9]
4. Address the parent's concern and surprise about challenging a child they were told was allergic. [1]

You are not expected to perform the challenge yourself in the station — you are explaining the pathway and the plan. Flag that the challenge is done under observation with the capacity to treat any reaction, so it is safe. [1]

Examiner prompt to the actor (parent)

"But she's been told she's allergic to penicillin her whole life — surely that's dangerous to test now? And if it wasn't an allergy, why did someone put it on her record? I don't want her to have a reaction just to prove a point." [10]

Marking domains

• Frame and explanation (3): explains clearly and in plain language that most childhood penicillin-allergy labels are not real (more than 90% cannot be confirmed), that a rash with a viral illness is the commonest reason for a false label, and that the label has simply never been checked — without dismissing the parent's concern. [3]
• The delabelling pathway (3): outlines the safe, structured pathway — history, a PEN-FAST risk check to confirm she is low-risk, and a supervised oral amoxicillin challenge under observation with the capacity to treat any reaction; reassures the parent that this is an evidence-based, safe process supported by the PALACE trial. [2] [1]
• The benefit of removing the label (2): explains that removing the label restores the safest, most effective first-line antibiotic for this pneumonia and for the rest of her life, and avoids broader-spectrum, more problematic antibiotics — the antibiotic-stewardship benefit. [9]
• Communication and empathy (2): acknowledges the parent's worry and the confusing record without defensiveness, uses plain language, checks understanding, and invites questions; does not overwhelm. [10]

Model answer — the explanatory script

"Thank you for coming in, and that's a really reasonable question. Let me explain why we think the label is most likely not a true allergy, and how we can check it safely." [3]

"When your daughter was two and had that rash, she was being treated with amoxicillin for what was almost certainly a viral illness. The rash you saw is exactly the kind of rash that viral illnesses cause in children — and it's also the classic situation where a rash gets blamed on the antibiotic when the virus was the real cause. More than nine out of ten children who carry a penicillin-allergy label turn out not to be allergic at all when we test them properly. So the label on her record has almost certainly never been a true allergy — it just got put there years ago and was never checked." [3] [10]

"Now, here's the safe way we check it. First, I take a careful history of exactly what happened — which we've just done — and that tells me she's low-risk. Then we use a simple checklist called PEN-FAST that confirms she's in the low-risk group. And because she's low-risk, the next step is to give her a dose of amoxicillin here, under close observation, with the team and the medicines ready in the very unlikely event she reacts. A large study called the PALACE trial showed this is just as safe as the old skin-test-first approach, and much quicker. So she's not having a reaction to prove a point — she's having a carefully watched test that, in almost every case, shows the child is fine." [2] [1]

"Why does it matter? Because if we remove the label, your daughter gets the best first-line antibiotic for this pneumonia — amoxicillin — and for every infection she has for the rest of her life. Carrying the label means she gets pushed onto other antibiotics that are broader, can have more side-effects, and contribute to antibiotic resistance. Removing a label that was never real gives her back the safest option." [9]

"And I completely understand it feels confusing that it was on her record at all — that happens very often, and it's exactly why we now make a point of checking these labels rather than just carrying them forever. If she tolerates the test dose, we update every part of her record — the hospital, the pharmacy, your own records, and your GP — so the label is gone for good. How does that sound, and what questions can I answer for you?" [10]