Other conditions that can cause a rash similar to the chickenpox rash include:

• Infection with a different virus that also causes a skin rash.
• Insect bites or scabies.
• Allergic skin reaction to a medication.
• Dermatitis herpetiformis.
• Erythema multiforme. This rash develops in the skin and mucous membranes (such as inside the mouth). It can be caused by an infection, an allergic reaction, or a disease condition. A severe form of this condition is Stevens-Johnson syndrome.
• Rickettsialpox, caused by the bacteria Rickettsia akari, which is transmitted by mites.