Rashes appear as bumps, spots and areas of redness on the skin. Often the result of allergic reactions or skin disorders, rashes cause itching, irritation and other symptoms. While some rashes occur only on the trunk or the extremities, some rashes spread over the entire body. Full body rashes have several causes.
Scarlet Fever
Group A streptococcus bacteria causes scarlet fever, which results in a scarlet-colored rash on the body. The rash usually affects the neck and face first, spreads to the back and chest and then spreads to the rest of the skin. If you press on areas affected by the rash, they usually turn white, according to the Nemours Foundation. After several days of infection, the rash fades, but the affected area may peel. Other symptoms of scarlet fever include fever, sore throat and swollen glands.
Drug Allergy
When someone experiences a drug allergy to a specific medication, the body takes several steps to produce an allergic response. Full body rashes commonly occur during allergic reactions to prescription and over-the-counter drugs. These rashes occur with other symptoms, such as itching, wheezing, swelling of the tongue and lips, hives and difficulty breathing. The University of Maryland Medical Center reports that common causes of drug allergies include anticonvulsants, penicillin, sulfa drugs, insulin drugs and x-ray contrasts that contain iodine.
Hives
Hives, also known as urticaria, appear as very red and swollen areas of the skin. They also cause intense itching. Hives appear due to allergic and non-allergic causes, and often occur as the result of an allergic reaction to foods and medications. Common food causes of hives include nuts, shellfish, berries, tomatoes and nuts, according to the University of Oregon. Common drug causes of hives include anticonvulsants, phenobarbital, sulfa drugs, aspirin, penicillin and yellow food dye No. 5. Other causes of hives include cold exposure, sunlight exposure, exposure to heat and rubbing of the skin by ill-fitting clothing.
Viruses
Viral rashes appear after exposure to viral organisms. Some of the most common viral rashes result from chickenpox, roseola and Fifth disease. Chickenpox causes fever and bumps on the skin. These bumps turn into blisters and eventually crust over. Roseola causes a fever that lasts for approximately three days, according to Dr. William Sears, an associate clinical professor of pediatrics at the University of California, Irvine, School of Medicine.
After the fever breaks, a rash consisting of bumps and red spots develops. This rash starts on the back and neck and spreads to the extremities. Fifth disease causes a rash that starts on the cheeks and spreads to the trunk, legs and arms.
Cellulitis
Cellulitis occurs when a break in the skin allows bacteria to enter the body. These bacteria cause inflammation, which makes the skin red, painful and hot. The skin rash appears very suddenly and grows rapidly during the first 24 hours of infection. Other symptoms of cellulitis include fever, warmth over the area of the rash, chills, muscle aches, fatigue and sweating. The National Institutes of Health reports that streptococcus and staphylococcus bacteria commonly cause cellulitis.
