Jimmy is a 20-year-old boxer who presents to his GP with an itchy and painful rash on his forearm for the past three days.

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<p>Jimmy is a 20-year-old boxer who presents to his GP with an itchy and painful rash on his forearm for the past three days.</p><p>He reports that, initially, just flat red lines were visible, but during the past 24 hours, blisters have formed.</p><p>He denies using any new products or consuming different foods than usual.</p><p>He remains systemically well and has had no recent illness.</p><p>He has been using an antihistamine, with temporary relief from the itch. </p><p>Of note, he has been camping recently in NSW but does not remember being bitten by anything.</p>

Dr Paul Muthiah is a GP on the Central Coast of NSW and medical co-editor of Australian Doctor.