Online studies have found that about five percent of Americans describe their relationships as “consensually non-monogamous,” meaning the partners have agreed to have more than one sexual and/or romantic relationship at the same time.

Consensual non-monogamy can take many forms, from polyamory to swinging to playing together; however, regardless of the specific sexual rules and boundaries negotiated, people who practice any type of consensual non-monogamy tend to be highly stigmatized.

A 2013 set of studies published in the journal Analyses of Social Issues and Public Policy found that monogamous relationships are consistently rated in a more positive light than consensually nonmonogamous relationships in virtually every way possible.

People believe monogamy is superior in terms of promoting trust, intimacy, and commitment; however, one of the biggest benefits people associate with monogamy is better health. The primary reason monogamous relationships are rated as healthier than open relationships is because they are seen as offering more protection from sexually transmitted infections.

The fact that people believe this isn’t surprising. In theory, monogamy should reduce, if not completely eliminate, infection risk. But in order to do so, one cannot stray. Ever.

If the Ashley Madison hack has taught us anything, though, it’s that a lot of us aren’t very good at monogamy.

The truth of the matter is that when we look at the way monogamy is practiced it isn’t necessarily any better for our health than being consensually nonmonogamous. As some support for this idea, consider the results of a study I recently published in The Journal of Sexual Medicine.

I recruited an online sample of 556 people in relationships (63 percent of whom were monogamous and 37 percent of whom were consensually nonmonogamous). Participants completed a survey that included questions about their sexual health history and practices, such as how many sex partners they’d ever had, whether they were currently sleeping with more than one person, how often they use condoms during sex, and whether they’d ever contracted a sexual infection.

I found that people in consensually nonmonogamous relationships reported more lifetime sex partners than those who were monogamous (6.4 vs. 3.9, respectively). That was expected, given that the former tends to have more sexual opportunities than the latter.

I also found that about three-quarters of people in open relationships said they currently had multiple partners; however, it turned out that nearly one-quarter of monogamous participants did, too!

This high rate of cheating was especially worrisome given that the vast majority of supposedly monogamous folks said that their partners did not know about their infidelity. In addition, compared to people in open relationships, monogamous people reported using condoms less often with all partners (primary and secondary) and were less likely to have ever been tested for STIs.

In other words, a large number of people in “monogamous” relationships were cheating, they weren’t telling their partners about it, they weren’t using protection reliably, and they weren’t getting tested to see whether they’d picked up any infections along the way.

The most surprising finding to emerge from this study occurred when I looked at participants’ sexual health histories. There was actually no difference between monogamous and consensually nonmonogamous participants in reported rates of sexually transmitted infections. About 1 in 5 people in each type of relationship reported having an STI before.

That’s right: people in open relationship were no more likely to have had an STI, despite the fact that they had about 40 percent more sexual partners than their monogamous counterparts.

These findings are inconsistent with the widely held belief that monogamy is safer and healthier than having an open relationship. Monogamy doesn’t appear to be offering the reduction in risk that is so widely assumed because far too many people are practicing it imperfectly. At the same time, people in consensually nonmonogamous relationships appear to be taking more precautions by using condoms more often, having better sexual communication, and getting tested.

In sum, people in monogamous relationships may not be as safe as they think they are, while consensually nonmonogamous relationships get a bum rap and aren’t as risky as most believe.

RELATED: Word on the Street: Are People Meant to be Monogamous?

Justin Lehmiller, PhD is a sex educator and researcher at Ball State University and author of the blog Sex and Psychology. Follow him on Twitter @JustinLehmiller.