How old do you have to be to get a lip tattoo?

I personally wouldn't let someone under 16 get a lip piercing but it can cause permanent damage. Lip piercings rub on your gum/teeth and can cause gum and enamel erosion and gum recession. Enamel doesn't grow back and neither do gums. Also, gum erosion leaves the tooth exposed and more susceptible to cavitites. Gum can be transplanted from other parts of the mouth to fix the problem though. Also, its extremely unattractive. Bioplast studs help with the problem but don't fully eradicate the risk. I think its better to wait till the child fully understands the risks that come with the piercing.