How do you treat severe eczema?

Protect. Avoid things that make you break out, soaps & wetness. Wash your hands only when necessary. Wear gloves when needed. Wear clothes made of cotton. Bathe only with a small amount of mild unscented soap, such as dove. Keep the water temperature cool or warm, not hot. Use the medicine your doctor gave you. Use a plain moisturizer daily. Avoid scratching or rubbing the itchy area. Manage stress.
Steroids, moisture. Treatment for allergic skin (eczema) involves steroids (corisone, triamcinalone, etc) and moisturizers. Avoid products that irritate or dry the skin, such as harsh soaps/cleansers and alcohol-based sanitizers.