Common causes of itchy, blistering skin rash are chickenpox and impetigo, according to WebMD and MedlinePlus. Chickenpox begins with a fever, a loss of appetite, headaches, sore throat and overall malaise.
With chickenpox, the rash appears a few days later after the onset of systemic symptoms, says WebMD. The rash mostly appears on the trunk and spreads to the face, the scalp and might even spread to the eyes. Over one or two days, the bumps of the rash turn into fluid-filled blisters. Eventually, they break and crust over. One complication of chickenpox is infection of the skin from the patient scratching.
Impetigo is another skin disease caused by bacteria entering an opening in the skin, says MedlinePlus. As with chickenpox, the skin also erupts in itchy, pimple-like sores that fill with pus, break, drain and crust over.