no age preference is necessary to buy or use them item. however, make sure it's right for you! some people have very sensitive skin, and nair will make them extremely itchy or cause other side affects depending on the persons skin.
Getting laser hair removal treatment can be administered anytime, but to have it be effective, you need to have all your permanent hair follicles developed. Depending on what area you are getting...
We don't need a long, boring answer. It depends on what your 3-year old wants! If she really wants to straighten her hair, just keep these rules in mind:1. Do it YOURSELF or find a responsible person...