What causes a fungus infection on a child's head, and what can be used to treat it?

Oral medicine. Tinea capitis is the name of the most common fungal infection that children get on the scalp. A common way to get it is by close contact with another person, and especially sharing hairbrushes, barettes, hair rollers, hats, etc. There is also a form that is transmitted by pets (cats and dogs.) it is treated by taking an oral prescription medicine (pills or liquid) for up to 6-12 weeks.