Chickenpox in a child is usually quite minor. They might have a slight fever but the most annoying part for them is the itching of the spots which can be treated with calamine lotion. As far as diet goes they can eat whatever they fancy but it is more important to make sure they get plenty of fluids. In an adult it can be more serious. Some people even have to be hospitalised with it. You may find you don't have much of an appetite in the early stages of the disease so it's important to drink plenty of fluids. Chickenpox is a herpes virus and related to cold sores and shingles. The best foods are yoghurt, fish, poultry and plenty of fruit and veg. Foods to avoid are nuts and seeds, grains, caffeine and chocolate. If you have it I wish you a speedy recovery.