Technically, your child could use baby shampoo all the way to adulthood if they'd like. However, as your child gets older and their hair gets thicker and more oily (and definitely when they start going through puberty), you may want to switch to a kids or adults shampoo, depending on their age. Kids shampoos should still be pretty gentle, but may also have some more ingredients to clean oil and help get hair cleaner. Usually, you'll want to make the switch once your child can wash their own hair without getting shampoo in their eyes. This will depend on your child, but sometime around 8 to 10 years old is a good estimate. Of course, you can also ask your pediatrician for guidance.