I don't usually do requests – they make me feel too much like a radio DJ. But this week a pharmacist asked me to write about penicillin allergy, and as it ties in with new, important draft Nice guidance, I'm happy to oblige. The Nice guideline in question focuses on anaphylaxis and its treatment. Surprisingly, there are no accurate statistics for the number of people affected in the UK, as inconsistent reporting and high rates of misdiagnosis create a muddied picture. The best estimate is that one in 1,333 people in the UK have experienced anaphylaxis and there are at least 20 deaths every year. Naturally, Nice focuses on referral pathways, ensuring patients who experience anaphylaxis have adrenaline injectors, and proper recording so we can get an accurate picture. The guidelines avoid the tricky questions of identification and prevention, though, and this is where pharmacists need to take the lead. Take penicillin, for example. Allergic reactions occur in 1-10 per cent of people who use the drug. While anaphylaxis occurs in less than 0.05 per cent of cases, its severe consequences mean prevention is essential. And as you probably know, 0.5-6.5 per cent of patients with penicillin allergy are also allergic to cephalosporins, complicating things further. So it's essential to ask your patients if they have an allergy every time you dispense a penicillin or cephalosporin. It's an approach that's going to get a lot of false positives; patients' definitions of allergy vary widely. But every so often you're going to find a patient with a genuine allergy who has somehow slipped through the prescribing safety net. And your intervention might just save their life. Chat with Chris: www.twitter.com/CandDChris or email him at [email protected]

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