Rash from chickenpox on the trunk of an 6 year old female patient with eczema. Chickenpox is a highly contagious infection caused by the varicella-zoster virus. It spreads easily from person to person and is most common in young children. The first symptom is an itchy, spotty rash that can spread over the entire body. The spots can fill with fluid and become blisters, some of which burst and lead to flaky scabs. It may also cause headaches and fever. For most people, chickenpox isn't serious and will heal on its own within a couple of weeks. The majority will also have immunity from it for the remainder of their lives. Symptoms can be eased with cooling creams and painkillers.