More than one in three Britons (35%) has had unprotected sex with a stranger or new partner while on holiday, according to a poll.
Those in their 50s are the least likely to use contraception with a new lover - about 16% compared with 4% of those aged 26 to 30 and 6% of people aged 22 to 25.
The survey of 3,000 people found alcohol and poor availability of condoms abroad as major reasons people do not use protection.
One in five over-50s said lack of condoms was the main reason they did not bother, while more than one in 10 blamed drink.
The poll included 144 people aged 51 to 55, 174 aged over 56, 497 aged 22 to 25 and 652 aged 26 to 30.
The research found people were willing to throw caution to the wind while abroad and enjoy a holiday romance or "quick fling".
Some 17% of those aged 51 to 55 said they would embark on a short-lived romance, while the figure rose to 30% of those aged 22 to 25.
Overall, more than one in eight women said they were embarrassed to ask about contraception when having sex with a new partner.
The Co-operative Pharmacy, which commissioned the research said May to September was the time of year people were most likely to visit sexual health clinics because of worries about sexually-transmitted infections (STIs).
Pharmacist Lisa McCreesh said: "On holiday people often get more amorous. We are urging people to remember that condoms provide the most effective protection against STIs.
"If you have had unprotected sex, it is important to get a check-up as you may not show any symptoms."
England's chief medical officer, Professor Dame Sally Davies, added: "Left untreated, sexually transmitted infections can lead to health problems - whatever your age, always wear a condom to protect yourself."