Road accidents are the main cause of adolescent deaths worldwide, say researchers, with car crashes and suicides the top two killers of teenagers in Australia.
An international study of adolescent health showed injuries accounted for 40 per cent of deaths in 10- to 24-year-olds worldwide.
This included injuries from car accidents and intentional harm caused by suicide and violence, with vehicle crashes the leading single cause of death.
Australian authors Susan Sawyer and George Patton, from Melbourne's Murdoch Children's Research Institute, say this shows most deaths are preventable.
"Irrespective of region, most adolescent deaths are preventable and thus strongly justify worldwide action to enhance adolescent health," the authors say.
Adolescent health has lagged behind other age groups which had been prioritised, including young children and the elderly, the authors say, in their call for better global youth health strategies.
Although mortality rates for children under the age of 5 have declined by more than 80 per cent in many countries in the past 50 years, adolescent deaths have reduced only marginally, they say.
Of 27 high-income countries, the US has the highest adolescent mortality rates because of violence and road trauma, and Singapore has the lowest. Australia is ranked 13th lowest.
Patton says Australia had experienced a substantial fall in road trauma casualties over time because of restrictions on speed, alcohol and improvements in licensing, and vehicle and road quality.
Tobacco use has also declined in Australia, but First-World health problems such as tobacco, alcohol and obesity have become more prevalent in low- to middle-income countries, Patton says.
The small Pacific island nation of Tonga has the highest rates of obesity, with two-thirds of teenagers aged 13 to 15 overweight.
Some countries in Latin America, North Africa and the Middle East also have the most overweight adolescent populations, in addition to historical health risks such as tuberculosis, HIV and maternal mortality.
"Most of the countries with the highest health risks of this kind, the heaviest kids, the least physically active kids, kids who are smoking - they are now in low- and middle-income countries," says Patton.
"We have really neglected this age group and that has important implications for the economies of these countries.
"These young people are the future.
"They need to be educated, they need to have jobs, but they also need to be healthy."
Susan Sawyer, director of adolescent health at the Murdoch Children's Research Institute, says social media have added to the health risks faced by young people, in terms of cyber bullying, sexting and pornography.
But she says social media could also be harnessed to promote healthy lifestyles to young people.
She says adolescents are now exposed to health risks, including sexually transmitted diseases, alcohol and drug misuse over a longer period than previous generations were, because young people are undertaking further education, entering full-time work and postponing marriage.
The special adolescent health issue of The Lancet coincides with the UN Commission on Population and Development, held in New York recently, which focused on youth.