Patient History: An elderly man was prescribed a course of flucloxacillin when he developed a chest infection. A few days later, he rang his GP in some distress to say that he had developed an itchy rash (image attached). Physical Examination: On examination, a generalized rash of pink wheals was seen, which appeared and lasted a few hours before fading and appearing elsewhere. On questioning, he recalled a problem many years before when he had 'itched' while taking an antibiotic, but it had passed without further problems.
He was not taking any other medications, apart from occasional paracetamol. He had no recent insect sting and had never reacted in this way to any foods, other medications or substances. However, an adverse reaction to the flucloxacillin was suspected and it was discontinued and an alternative antibiotic substituted. What is the probable diagnosis for this patient?…
