Katharina Dworzynski1, Michael Ardern-Jones2, Shuaib Nasser3. 1. National Clinical Guideline Centre, Royal College of Physicians of London, London NW1 4LE, UK Katharina.Dworzynski@rcplondon.ac.uk. 2. Department of Dermatopharmacology, Southampton General Hospital, University of Southampton, Southampton, UK. 3. Department of Allergy, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.