The Department of Health has launched a campaign to let the public know that the legal age to smoke tobacco will rise to 18 years from 1 October this year.
The change follows the introduction of smokefree legislation earlier this month and hopes to reduce the number of young UK smokers.
Today around 9% of 11 to 15-year-olds and 26% of 16 to 19-year-olds smoke tobacco.
The NHS will support teenagers who wish to quit through a NHS Smoking Helpline.
Minister for Public Health Dawn Primarolo said: "Currently, half of all teenagers who smoke will die from diseases caused by tobacco if they continue to smoke throughout the course of their life.
"Raising the minimum age at which teenagers can be sold tobacco products will reduce the availability of cigarettes, and could therefore discourage young people from taking up smoking in the first place."
Retailers who sell tobacco to under 18s will be fined up to £2,500.
Association of Convenience Stores Chief Executive James Lowman said: "The government's campaign must ensure that everyone knows what is expected of them when the law changes."