Beer combines multiple eczema triggers in a single drink: histamine from fermentation, wheat and barley proteins that can trigger immune reactions in grain-sensitive people, yeast that cross-reacts with a skin fungus linked to eczema, and alcohol that impairs histamine breakdown and increases gut permeability.

This makes beer one of the more complex triggers to untangle. Unfiltered craft beers and wheat beers (Hefeweizen, witbier) have the highest histamine levels and the most residual grain proteins, making them the highest-risk options. Filtered, pasteurised lagers have the lowest histamine and fewest grain proteins. If only certain types of beer trigger a reaction, identifying whether the response follows histamine content, grain type, or yeast presence can help narrow down the underlying mechanism.