Allergic skin reactions are very common, and it can be difficult to figure out the exact cause. There are many different kinds of rashes that can be caused by many things. Among these are plants (like poison ivy), allergic reactions to a medication or a food, or a response to an illness (mostly viral).
Allergic eczema (atopic dermatitis) and hives (urticaria) are two of the most common skin rashes. Eczema affects 10 percent to 20 percent of children and 1 percent to 3 percent of adults. If you have eczema, your skin may become red, irritated and itchy. Sometimes there are small, fluid-filled bumps that ooze.
Hives (urticaria) are bumps or welts that appear on the body and are usually very itchy. About 20 percent of Americans have hives at some time in their lives. It can occur in combination with swelling of the face, lips, eyes or extremities (angioedema)
Contact dermatitis is caused by skin contact with either an allergen or something irritating (like soap, detergents and some plants), causing symptoms such as a rash, blisters, itching and burning. Most cases of contact dermatitis are not caused by an allergen but by irritants. Metals in orthopedic and dental implants and ingredients and stabilizers of creams, lotions, soaps and food can also be responsible for skin allergies.