Wales has become the first country in the UK to introduce a nationwide ban on the intimate piercing of under-18s.
The law, which comes into force on Thursday, makes it an offence for piercing practitioners to arrange or carry out an intimate piercing on anyone aged under 18.
There are 10 specified intimate body areas where piercing is banned - including genitalia, nipples and tongues.
The change will come under the Public Health (Wales) Act 2017, making it an offence to arrange or perform intimate piercings on children and young people.
Wales will become the first country to issue a nationwide ban, though some local authorities across the UK have introduced restrictions on intimate piercings.
Dr Frank Atherton, chief medical officer for Wales, said the law was in place to protect "health and well-being".
"It's concerning that a third of young people with intimate piercings have reported complications following a procedure," Dr Atherton said.
"The child protection issues that could also arise from this scenario highlight even further the importance of implementing such a law.
"I hope this piece of legislation will help to reduce these issues, and that practitioners understand the importance of obtaining proof of age beforehand."
The Welsh Government said a study in England found that complications were reported with around a third of all body piercings in people aged 16-24.
Problems were most likely to be reported with tongue piercings, followed by genital piercings and nipple piercings, it stated.
"As young people continue to grow during their teenage years, an intimate piercing performed at a young age could result in further complications arising as their bodies develop," a spokeswoman said.
"Young people may also be less likely to have the experience or knowledge of how to clean or maintain an intimate piercing, leading to an increased risk of infection."
Dr Colette Bridgman, chief dental officer for Wales, said many dentists and patients welcome the ban.
"Tongue piercing can lead to lasting damage to teeth and gums, and can cause serious swelling in the mouth that can affect breathing," Dr Bridgman said.
"Many dentists in Wales have seen patients who have permanent harm following piercing and dental teams in Wales really welcome this new law."
Local authority enforcement officers and police officers in Wales have received training ahead of the law coming into effect.
Intimate piercing practitioners in Wales are urged to have a "rigid system" in place to help them confirm proof of age and to obtain consent for each procedure, the Welsh government said.
The Public Health (Wales) Act received Royal Assent in July last year.
It covers a focus on obesity and protection from the harms of smoking, especially for children and young people, and requires retailers to be on a national register.
The law also covers protection from the risks of infection from procedures including body piercing, electrolysis, acupuncture and tattooing through a new licensing system.