What product is good for relieving and preventing eczema rashes?

Emollients. Prevent dry skin by taking warm (not hot) showers or baths. Use a mild soap or body cleanser. Apply an effective emollient to your damp skin. Emollients inhibit the evaporation of water. Generally, they are available in jars and have a "stiff" consistency. Applying them to wet skin is the key. You might want to try cetaphil restoraderm or cerave. Try not to itch. C u'r doctor if this doesn't help.