Figures show 9% of 11- to 15-year-olds in the U.K. use vapes, despite it being illegal to sell them to young people under the age of 18.

The U.K. government on Monday announced it will ban disposable vapes, citing an “alarming rise” in the number of young people using them.

There will also be new restrictions on how vapes can be packaged and displayed, as well as the flavors they can come in.

Brightly colored e-cigarettes which are used once and thrown away have proliferated in the U.K. and other countries in recent years.

Pointing to the nicotine content that is typically present in many vapes, the U.K. government on Monday warned that withdrawal from the substance can sometimes cause “anxiety, trouble concentrating and headaches. While vaping can play a role in helping adult smokers to quit, children should never vape.”

It is illegal to sell vapes to consumer under the age of 18 in the U.K., but according to government figures, 9% of 11- to 15-year-olds use them. The number of children vaping has tripled over the last three years, it said.

Shops that sell vapes to children face higher spot fines.