If the offending drug is avoided, the rash normally clears itself in two to four weeks. You can try cool, moist compresses, anti-itch lotions, and other self-care measures to soothe your skin. In severe cases, oral steroids may be needed to reduce inflammation and prevent further damage to the skin. Allergic reactions are caused by antibodies that are released into the blood when they encounter a substance called an allergen. The antibodies then trigger a response from special cells of the immune system. This response involves many processes inside immune cells and elsewhere in the body. It results in the production of more antibodies and activation of more immune cells than would otherwise occur. These additional responses help the body fight off the antigen (allergen) that triggered the reaction. The type of antibody involved in allergic reactions is called immunoglobulin E or IgE. When an allergen binds to IgE on the surface of a cell, it triggers another protein on the cell membrane to split into two parts. One part remains attached to the membrane while the other part floats free into the surrounding space. This free part is known as soluble CD23. Soluble CD23 acts like a scavenger receptor for IgE, binding to it and carrying it out of the cell via urine and feces. IgE plays a central role in allergic reactions.