Eggplant is notable for having one of the highest histamine levels among common vegetables. Histamine is the same chemical the body releases during allergic reactions — it makes skin red, itchy, and inflamed. For the roughly one third of people with eczema who have reduced ability to break down histamine (histamine intolerance), eating high-histamine foods like eggplant can directly worsen the skin.

The allergenic proteins in eggplant are concentrated in the purple peel, so peeling before cooking reduces allergen load. Eggplant is also part of the nightshade family. A common practical trap: eggplant Parmesan combines three high-histamine ingredients — eggplant, tomato sauce, and aged cheese — in a single dish, making it one of the higher-risk combinations for histamine-sensitive individuals.