About a fifth of young people with body piercings get health problems, a new report has shown.
The most common problem is an infection, but bleeding and tearing around the piercing also happen quite a lot.
And if the person doing the piercing doesn't use a clean needle, it can lead to serious problems like blood poisoning and HIV.
Earlobes are the most common piercing, but belly buttons and the tops of ears are also popular.
In the UK, there's not actually a law which stops young people having piercings, but almost all shops have their own restrictions for under 16s or under 18s.
Most say you must have your parent's consent.