Over 3,000 youngsters die every day, totalling 1.2 million deaths a year, from largely preventable causes, according to a new report from the World Health Organization (WHO).
Around 1.2 billion people, or one in every six persons, are adolescents aged between 10 to 19 years.
The report entitled 'Global accelerated action for the health of adolescents (AA-HA!): Guidance to support country implementation', was scheduled to be launched on Tuesday in Canada at the Global Adolescent Health Conference: Unleashing the Power of a Generation.
The report states that the biggest causes of death among adolescents are road traffic injuries, lower respiratory infections and suicide, which caused respectively 115,302, 72,655 and 67,149 deaths.
While most of these deaths could be prevented with good health services, education and social support, in many cases, adolescents who suffer from mental health disorders, substance abuse or poor nutrition cannot obtain critical prevention and care services -- either because the services do not exist, or because they do not know about them.
"Adolescents have been entirely absent from national health plans for decades," said Flavia Bustreo, Assistant Director-General, WHO.
"Relatively small investments focused on adolescents now, will not only result in healthy and empowered adults, who will thrive and contribute positively to their communities, but it will also result in healthier future generations, yielding enormous returns," Bustreo added.
Interventions such as seat-belt laws to comprehensive sexuality education can help countries to improve the health and well-being of their adolescents and dramatically cut unnecessary deaths, the report recommended.
Besides these causes, in low- and middle-income countries in Africa, communicable diseases such as HIV/AIDS, lower respiratory infections, meningitis and diarrhoeal diseases are the biggest killers.
The leading cause of death for younger adolescent girls aged between 10-14 years are lower respiratory infections, such as pneumonia -- often a result of indoor air pollution from cooking with dirty fuels.
For girls in the 15 to 19 years age group, it is pregnancy complications, such as haemorrhage, sepsis, obstructed labour and complications from unsafe abortions that cause the deaths, the report said.
Adolescents are also at very high risk of self-harm and suicide as it is the leading or second cause of adolescent death in Europe and South-East Asia.