In 10 percent cases, teenagers have slept with someone without even knowing their name whereas older youths are risking pregnancy and infection with 60 per cent of 16 to 22-year-olds failing to use a condom.
Two out of three said they were more concerned about having a good time than sexually transmitted diseases or having a baby.
The findings have questioned Government in its drive to cut the number of teenage pregnancies in Britain, the highest in Europe.
Only one in three uses a condom every time they have sex, rather 25 percent said that condom turns them off, according to a poll of 1,200 young people by high-street store Superdrug.
Twelve per cent of 22-year-olds have slept with more than one person at once whereas just 18 per cent polled were virgins.
"Levels of teenage pregnancies and STIs are appallingly high," News Of The World quoted Superdrug''s Mel Wilson as saying.
Pop stars JLS have joined Superdrug to launch a range of condoms to get young people to practise safe sex.