Under-18s are no longer able to get botulinum toxin injections or dermal lip fillers for cosmetic reasons in England.
The new law aims to protect young people from harm after years of efforts to regulate the non-surgical beauty industry.
Campaigners say the rules do not go far enough.
The ban does not cover other procedures like thread lifts some seek to get the popular ‘fox-eye’ look.
Government estimates show up to 41,000 Botox-style procedures were carried out on under-18s in England last year.
And the analysis, by the Department of Health and Social Care, suggests there were up to 29,300 dermal filler procedures for under-18s in 2017.
Before the new legislation came into place in England, under-18s were able to have Botox-style procedures and dermal fillers with no checks on their age.
Updates on legislation in Wales and Scotland are expected in the near future, while Northern Ireland has no current plans to make any changes.
Campaigners are calling on the other nations to act quickly to prevent young people in England travelling over the borders for treatments.
There remains no law in the UK requiring practitioners to have formal qualifications or training for this type of treatment.