A rash after you eat something feels simple, but skin allergy rarely is. We sit down with board-certified dermatologist and Mohs surgeon Dr. Carsten Hamann to break down systemic contact dermatitis, a lesser-known form of allergic contact dermatitis where reactions can be triggered not just by skin contact, but sometimes by ingestion. We unpack how this differs from true food allergy, why eczema and allergy can look identical, and why nickel—found in both products and foods—is such a common and surprising culprit.
We also cover other rare triggers like cobalt, chromium, and fragrance components like Balsam of Peru, plus how certain foods and dyes can mimic or worsen reactions. If you’re stuck wondering “eczema or allergy?” the takeaway is practical: seek patch testing, take a detailed exposure history, and test changes intentionally instead of guessing.
