Rashes are often caused by contact with an irritating substance or allergen, according to WebMD. Common causes of rashes include poison ivy, soaps, perfumes, latex, jewelry and fabrics. Sometimes rashes are caused by viral infections, such as herpes zoster, or bacterial infections, such as impetigo.
Contact dermatitis rashes generally appear within 48 hours of contact with the irritating substance, states WebMD. Although these rashes can be very itchy, they are not usually serious. Patients can expect contact dermatitis to clear up within two to four weeks if they are able to avoid the offending substance, states Mayo Clinic. Uncomfortable rashes can be soothed with cool, wet compresses and anti-itch creams.
Herpes zoster, or shingles, can cause a painful and itchy red rash to develop over an isolated section on one side of the body, according to Mayo Clinic. Other symptoms of shingles include numbness and tingling, fever and sensitivity to light.
Impetigo is a bacterial infection that sometimes develops after a child scratches a sore or rash repeatedly, states KidsHealth. Non-bullous impetigo begins as small blisters that develop a yellowish-gray crust, while bullous impetigo forms larger, fluid-filled blisters. Both forms are contagious, and since they are itchy, they are easily spread from one part of the body to another when scratched.