Government proposals to make the dangers of drugs a compulsory subject in all English schools have been welcomed by anti-drug campaigners.
Reforms to Personal, Social and Health Education (PSHE) classes would see the lessons become mandatory in primary and secondary schools.
Children's minister, Baroness Delyth Morgan, said that initial lessons targeted at five year olds could cover dangerous substances in the home such as bleach or painkillers. As they get older they could learn about the risks of Class A drugs such as heroin and cocaine, as well as drug and alcohol laws.
The age at which children begin learning about illegal drugs could depend on the child and their surroundings, Baroness Morgan said.
"You could imagine a situation in some places where, on their way to school, a child could come across a needle," she said, adding that in that situation it might be appropriate to raise the subject earlier.
A spokesman for children's health education charity, Life Education, said: "If we want to make a real and lasting difference to teenage drug and alcohol misuse, we must reach them early - at primary school.
"Then, as they reach adolescence and are most at risk from peer influence, they can make informed decisions based on fact rather than hearsay."