How can I know if my baby has eczema or some other kind of rash?

Eczema. Affected areas usually appear very dry, thickened, or scaly. In fair-skinned people, these areas may initially appear reddish and then turn brown. Among darker-skinned people, eczema can affect pigmentation, making the affected area lighter or darker. In infants, the itchy rash can produce an oozing, crusting condition that occurs mainly on the face and scalp, but patches may appear anywhere.