Butter is about 80% fat and only about 1% protein, which means it contains far less of the milk proteins that trigger eczema than a glass of milk or a slice of cheese.

Because of this low protein content, many dairy-sensitive people can tolerate butter in moderate amounts without a flare. Clarified butter (ghee) takes this further — the clarification process removes nearly all milk solids, reducing protein to less than 0.01%. Most people with mild dairy sensitivity tolerate ghee without problems. However, for people with severe milk allergy, even the small amount of protein in regular butter can be enough to trigger a reaction. When testing dairy tolerance, ghee is generally the safest starting point, followed by butter, then baked dairy, with liquid milk as the last step.