Research from NHS Greater Glasgow and Clyde's Sandyford Initiative has revealed that almost half of west of Scotland men who pay for sex already have a partner.
Men "playing away" on holiday were identified as twice as likely to have unprotected vaginal sex as those paying for sex in Glasgow.
The research, which appears in October's Sexually Transmitted Infections Journal, surveyed more than 2600 men attending the Sandyford sexual health clinic in Glasgow between October 2002 and February 2004.
The two authors of the study, Dr Tamsin Groom and Dr Rak Nandwani, are both based at the Sandyford Initiative, which provides a regional integrated sexual health service for almost two million people in the west of Scotland.
Dr Groom said: "Very little is really known about these men, their behaviours and the risks they may pose to themselves or indeed their partners.Exploring the issue of paid for sex allows us to target health promotion and services to people engaged in prostitution, their clients and the partners of both of those groups."
A standard health screening questionnaire completed by the men who took part revealed that one in 10 had paid for sex. Their average age was 34.
Almost half (43%) said that they were in another relationship when they had paid for the sex.
And more than half (56%) who said they had had paid for unprotected vaginal sex already had a partner at the time.
More than half the men surveyed said they had paid for sex while abroad.However four out of 10 said they had paid for sex locally. Around 2% said they had paid for sex both in the UK and abroad.
The majority of the men (66%) had paid for sex in the preceding year, and around one in four said that they repeatedly used prostitutes. But the time frame ranged from two days to 30 years earlier.
Unprotected vaginal sex was almost twice as common among those who paid for sex while abroad.
Although none of the men surveyed had an HIV infection, one in five had a sexually transmitted infection, including Gonorrhoea, Chlamydia and Syphilis.
Another interesting finding of the study was that there was a high volume of men paying for unprotected oral sex locally and that half of these men were in long-term relationships.
Dr Nandwani, the study's co-author, said: "There is lack for awareness in the heterosexual population that oral sex alone can facilitate STI transmission including herpes, syphilis and HIV.This is an extremely important health message and in gathering this information will give us a better understanding of those people who use our services."
Dr Groom added: "This study is a snapshot of behaviours associated with paying for sex, far more information can easily be obtained by improving the detail of documentation and I hope this study will show others that it is possible to ask men about paying for sex in a sexual health setting. It reveals important health implications for partners and further highlights the tendency to take more risks on holiday. It may in future be useful to point out these risks to the men who pay for sex so they can protect themselves as well as those they care about."
Sexual health is a key priority for NHS Greater Glasgow and Clyde, a huge amount of work is underway to tackle sexual, reproductive and emotional health issues.
NHS Greater Glasgow and Clyde's Head of Inequalities and Health Improvement, Sue Laughlin said: "NHS Greater Glasgow and Clyde, alongside its partners, has made a commitment to addressing the issue of prostitution.
"This survey gives valuable evidence in understanding men's risk taking behaviour and its impact on the wider community."
The report is available on-line at http://press.psprings.co.uk/sti/october/364_st20537.pdf
For further information please contact the NHS Greater Glasgow and Clyde press office on 0141 201 4429.