Simon is a 25-year-old engineer who presents for review of recurrent rash affecting the wrists, forearms, axillae and abdomen.

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<p>Simon is a 25-year-old engineer who presents for review of recurrent rash affecting the wrists, forearms, axillae and abdomen (pictured).</p><p>This has occurred twice in the past year, both while running. The rash is itchy and associated with fatigue and shortness of breath, which meant he couldn’t complete the run.</p><p>Each of these episodes occurred when Simon was “running off” a large lunch of beer and pizza.</p><p>Simon runs 3-4 days a week, usually before breakfast, without any similar symptoms.</p><p>He has no known allergies to medications, food or alcohol.</p><p>Typically the rash resolves spontaneously within 2 hours of stopping exercise, with an oral antihistamine.</p>

Dr Kate Kelso is a GP and medical editor at Australian Doctor.