Schools must teach children more about the dangers of alcohol as "significant" numbers of teenagers risk their health through drink-fuelled sex, Ofsted has said.
Overall education on drugs and addiction has improved since 1997, according to a new report from inspectors.
But Ofsted said pupils were most concerned about health risks associated with alcohol and tobacco.
In its Drug Education in Schools report, the watchdog said: "A significant number of young people regularly place themselves at risk by drinking to excess and in sexual activity, the latter often influenced by the former."
Pupils are much more likely to try cigarettes and alcohol than illegal drugs but too many schools do not teach enough about these issues, the report said.
Drug education in England had "improved markedly" in recent years, inspectors found.
But their research, based on more than 200 school inspection reports and 60 school visits, identified several problems that must be addressed. n Some teachers lack uptodate specialist knowledge of drugs issues; n Some parents are not playing their part in teaching children about the dangers of drugs, "placing their own children as well as others at considerable risk"; n Too many schools do not understand their pupils' needs; n Pupils want better education about alcohol and tobacco because they believe these pose the greatest health risks; n Some schools do not give enough time to drug education.
Chief inspector of schools David Bell said he was pleased that the overall standard of drug education had improved since Ofsted's previous national survey eight years ago.
"It is encouraging that schools are making good provision for drugs education," he said.
"Schools are doing a vital job of educating young people about the dangers of drugs, and take their role very seriously. But more schools need to work towards, and ultimately meet, the criteria for providing for pupils' emotional health and well-being." Ofsted criticised a lack of joined-up planning in secondary school drugs education.
"Too few drug education programmes make links to other personal social and health education themes such as sex and relationships education," the report said.
"As a result, the planning and subsequent lessons do not make any link between drug use and risk-taking sexual behaviour."
Ofsted found the majority of schools had no intention to use sniffer dogs or random testing to combat drug use among pupils.
The finding comes after the Abbey school in Faversham, Kent, introduced random drugs tests for pupils earlier this year.
Researchers at Buckinghamshire Chilterns University College have also claimed that sniffer dogs are effective and popular with pupils.
Schools Minister Andrew Adonis insisted that headteachers were in the best position to decide how to tackle the issue of illegal drugs in schools.
"Education programmes to steer young people away from damaging their health and opportunities have never been better," he said.