The age at which people grow armpit hair varies, but for boys it is often between the ages of nine and 14. Girls typically begin to grow this hair between eight and 13 years of age.
Children go through a period of puberty and each child goes through this at a different time. During puberty, in addition to growing armpit hair, children begin to grow taller. Girls start to develop breasts while boys begin developing facial hair. All children may experience emotional changes as they go through puberty. This can include mood swings and depression. Since the limbs also grow during this time, the child may also be clumsy or awkward.