Chickenpox is a viral infection that causes an itchy rash with spots all over the body. The rash begins as small red bumps that look like pimples or insect bites and then develops into thin-walled blisters. The rash can appear anywhere on the body, including inside the mouth and around the genitals, and can be harder to see on brown and black skin. The rash can be accompanied by other symptoms such as fever, headache, sore throat, or stomachache. The rash caused by chickenpox appears 10 to 21 days after exposure to the virus and often lasts about 5 to 10 days. The rash goes through three phases: small red spots, blossoming blisters, and scabbing stage. The blisters are very itchy and may burst, and then turn into scabs. The rash may spread wider or be more severe in kids who have weak immune systems or skin disorders like eczema. If you think you or your child might have chickenpox, call your health care provider.