Coffee's relationship with eczema is poorly studied — there are no controlled clinical trials examining whether eliminating coffee improves eczema. Several plausible mechanisms exist: coffee contains salicylates (aspirin-like compounds), it may reduce the body's ability to break down histamine (worsening reactions to other trigger foods), and caffeine stimulates the stress hormone cortisol.

However, caffeine is also a PDE inhibitor — the same mechanism used by some eczema medications — which means it could theoretically have anti-inflammatory effects. Community reports are mixed. A more productive line of investigation is usually what is added to coffee: milk, cream, flavoured syrups, and certain coffee blends all carry their own trigger potential that may be more relevant than the coffee itself.