Skin rashes can occur from a variety of factors, including infections, heat, allergens, immune system disorders and medications. One of the most common skin disorders that causes a rash is atopic dermatitis, also known as eczema. A rash is a noticeable change in the texture or color of your skin. Your skin may become scaly, bumpy, itchy, or otherwise irritated. Rashes also have the tendency to suddenly appear and disappear.
A rash is any area of irritated or swollen skin on your body. Rashes are often itchy and painful and can appear differently on different skin tones. While they are often described as red, on darker skin tones they may be purple, grey or white.

Many things can cause skin rashes, including:

Allergens in food or in the environment.
Bacterial infections, such as strep throat.
Skin conditions like eczema.
Irritants.
Viruses.

To eliminate the possibility of allergy an IGE test can be taken. If IGE levels are high a comprehensive allergy test should be taken to ascertain the root cause. If IGE is within limits other causes need to be explored.