People who cheat on their partners are more likely to have unsafe sex than those in open relationships who don't need to hide their sexual straying, a new study finds.

In the study, people in monogamous relationships who cheated on their partners were less likely to use condoms, and less likely to discuss their history of sexually transmitted diseases (STDs) during their sexual digression compared with people in open relationships who had sex with someone other than their primary partner, the researchers said.

The results suggest those who are unfaithful have a higher risk of acquiring a sexually transmitted disease, and possibly transmitting it to their partner, than those in open relationships, the researchers said.

Terri Conley, of the department of psychology at the University of Michigan, and colleagues surveyed 308 individuals in monogamous relationships, and 493 people in open relationships who have an agreement with their partner that monogamy is not required.

All participants in both groups had had sex outside their primary relationship. Participants were asked about the safe sex practices they used in their last sexual encounter outside their primary relationship.

The researchers found that 48 percent of unfaithful people reported using a condom during their sexual digression, compared with 66 percent of individuals in an open relationship.

In addition, 34 percent of unfaithful individuals reported talking about their sexual history and previous STD testing before engaging in sex, compared with 63 percent of those in open relationships.

The cheaters were also less likely to cover or sterilize sex toys before using them, compared with those in open relationships.

Previous research has shown unfaithful people do not accurately perceive the effect their cheating will have on their partners' mental health, and the new results suggest those who cheat also misperceive, or do not accept, the physical health risks of sex outside their relationship, the researchers said.

Health practitioners "may consider encouraging their monogamous patients to discuss specific definitions of monogamy, and to form a plan for coping with lapses from these agreements," the researchers wrote in their study, published March 29 in the Journal of Sexual Medicine.

"Such a plan may facilitate sharing of appropriate health information among members of the couples, and thus prevent further spread of [STDs]."

Pass it on: Cheating not only increases the risk of mental health problems for those in the relationship, it also increases the risk of STD infection.

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