Those who cheat are more likely to get STDs than those that have agreed on an open sexual relationship, a study has found.

Those who jump into bed with a stranger without their partner knowing are more likely to have consumed large quantities of alcohol - the reason for their reckless behaviour, while people in open sexual relationships don’t see sleeping with other people as cheating and are less likely to behave irrationally or irresponsibly when it comes to sex.

Using an online questionnaire means to communicate with their test group of 1647 people, researchers tested whether people consider monogamy as a way to prevent STDs from spreading. They also investigated at whether those in open relationships practise safe sex.

The results showed that 801 people admitted to having sex with someone other than their partner.  493 participants said they were in an open relationship when it happened. The other 308 admitted that they had cheated on their partner during their monogamous relationship.

Findings showed that cheaters were 27 percent less likely to use a condom during vaginal sex and 35 percent less likely during anal sex as compared to those in open relationships.

Not only were cheaters more likely to engage in risky sexual behaviour, there was also a 64 percent higher chance that they had engaged in drug and alcohol use.

"If people do not find monogamy appealing or feasible, they clearly need to think about the risk this poses to their partner and consider whether an open relationship would suit their needs better, and better protect their relationship partners," said study researcher Dr Terri Conley of the University of Michigan.

Irwin Goldstein, editor-in-chief of The Journal of Sexual Medicine where the study is published, said: "This research is of particular interest because it reveals that monogamous relationships are not always monogamous which can have resultant sexual health implications."