We Don't Really Know How Well Condoms Work for Anal Sex
Regulators and researchers have shockingly limited information on how condoms hold up in anal as opposed to vaginal sex, two entirely different physical contexts, involving discrete types of tissue, muscle force, and natural lubrication, or lack thereof.
Medical authorities have, for decades, promoted condoms as the gold standard for protection from HIV during all sex, be it oral, vaginal, or anal. Even in an era of relatively accessible low viral load management and PrEP, which drastically lower the risk of HIV transmission during sex without a condom, experts still tout the value of rubbers. “Given where we are with gonorrhea and syphilis,” says Carl Dieffenbach, director of the AIDS program at the National Institute of Allergy and Infectious Disease (NIAID), referring to a pattern of both increasing infections and drug resistance, “if you don’t know your partner very well, condom use is probably a good idea until you can both get tested.”
The US government has a long history promoting condom use, especially for anal—the riskiest kind of sex for disease transmission thanks to the sensitive nature of anal tissue. Despite that, the US Food and Drug Administration (FDA), which regulates what “medical devices” like condoms can be marketed for, has never “specifically approved or cleared a female or male condom for use during anal intercourse,” as FDA spokesperson Deborah Kotz tells me.
This might seem like a small bureaucratic oversight. However it speaks to the fact that regulators and researchers have shockingly limited information on how condoms hold up in anal as opposed to vaginal sex, two entirely different physical contexts, involving discrete types of tissue, muscle force, and natural lubrication, or lack thereof.
None of this means condoms are unsafe for anal sex. “The fact that condoms are over the counter,” Dieffenbach says, “means that they’re safe to use any way you see fit, unless you’re going to stick them down your throat and use them to choke on.” Kotz adds that the data that is available on condom efficacy for anal still shows that they “offer significantly greater protection against sexually transmitted infection (STI) transmission compared to no condom use.” However, as FDA researchers pointed out in a still seminal 1997 study, this does mean that we don’t exactly know how much more often condoms break or slip off in anal as opposed to vaginal sex and the increased risks that leads to.
Gaining a better understanding of what anal does to the average condom and its STI transmission prevention efficacy could allow the FDA to clear them for specifically anal marketing. It could also help guide the development of more effective condom designs for anal. And it could help researchers and public health officials “in targeting HIV prevention efforts, for informing HIV prevention messaging, for modeling studies, and for personal decision-making,” Johnson says.
So why haven’t we seen the kind of research that would help us understand more about how standard condoms function in anal sex in general, when clearly the data it could yield would be deeply valuable?
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We do know how anal sex likely uniquely affects typical latex condoms. The FDA acknowledges that condoms may break more often during anal, since rectums don’t self-lubricate like vaginas, and so can create serious friction without the copious use of lube. Charlie Glickman, a sex educator and author of The Ultimate Guide to Prostate Pleasure, notes that “there are still plenty of people who don’t know that you should use lubricant for anal sex.” Others may be using an improper lube for anal. Beyond the clear risks of degrading latex condoms with oil-based lubes, or causing problems for the condom or rectum with products not intended for sexual usage, Matt Mandell, the owner of prophylactic superstore Condomania, has observed that the rectum seems to absorb water-based lubes, making them rapidly ineffective at reducing friction. Glickman adds that water-based lubes seem to irritate the lining of the rectum, raising risks of micro-abrasions or tears in sex, and as such the risk of transmitting an infection if a condom does break or slip.
“This is an anecdotal note,” Glickman adds, “but it does seem that condoms might be more likely to slip off during anal intercourse. If you insert so far that the base of the condom goes inside the anus, the ring of the rectum will have a tendency to pull back on the base of the condom more than the vagina does.” This seems to be in accord with what the FDA says, and others’ observations that condoms may slip more often in anal than vaginal sex.
So even if you do use a reliable lube—like a silicon or water-silicon hybrid product—to reduce the likely higher risk of a break, you may still run an extra risk of slippage. Then, because of the sensitivity of anal tissue (and the risk of causing extra damage to the rectum by thrusting too hard and fast if excessive amounts of an appropriate lube mask sexual intensity), the risk of those slips leading to disease transmission is likely still elevated relative to similar slips in vaginal sex.
The magnitude of these specific risks, though, remains unclear. Some studies indicate that overall breakage and slippage rates in anal are similar to those in vaginal sex: around 2 percent. Others have found higher breakage rates for anal over vaginal sex.
Different techniques yield radically varied results: In 2015, for example, a CDC team determined that typical anal condom use reduced the risk of HIV transmission 64 percent for the penetrating partner, and 72 percent for the receiver, lower than the 80 to 85 percent effectiveness found in studies on HIV transmission with typical vaginal condom use. But in 2018, Wayne D. Johnson, HIV/AIDS researcher at the Centers for Disease Control and Prevention (and his team), using new methods and data, found 91 percent efficacy for typical anal condom use. Researchers openly acknowledge the limits of their methods.
However it’s hard to tell for any of these anal rates how much of the slippage or breakage observed was influenced by the amount or type of lube used. Or how much user error, like unrolling the condom before putting it on versus rolling it down the shaft all the way to the base, came into play. Or how long, deep, or intense the intercourse involved was. As you can image, these are hard factors to measure, but they are all key to condom failure in anal and vaginal sex.
Most of these studies have also only looked at latex male condoms as opposed to other types like nitrile female condoms, which many men who have sex with men reportedly use for anal as a matter of comfort and sensation, and which some believe may be more resilient to tears. (They may, however, also be more prone to slippage than latex male condoms.)
A lack of clear information on the physics of anal sex and its effects on condoms likely played a role in the FDA not clearing condoms explicitly for anal sex, despite the higher HIV transmission risk of anal sex in the ‘70s and ‘80s that seemingly led the FDA to more proactively study condoms’ efficacy. Kotz, the FDA spokesperson, notes that the agency can now only clear condoms to be marketed for anal use if a condom maker asks to do so and supplies them with data showing clear and adequate efficacy.
That might mean conducting something like a trial in which couples where one partner has a penis and the other a vagina and both already engage in regular vaginal and anal sex use a number of the same standard latex condoms for both types of sex equally and record all the details of sex using those rubbers, including all the slips and breaks.
But that kind of testing would be complex and expensive. And, as Mandell notes, condom makers do not have any real incentive to take on that task. People already buy condoms for anal sex thanks to existing sex education and medical recommendations. If a study proved the risks of extra slips or breaks are negligible, Mandell doubts this would notably increase sales. Any of the limited new sales that did emerge would be split among all manufacturers, not just the one who ate the costs of a study on standard condoms. Companies may also fear losing sales by specifically marketing, or even being associated with a study on, anal usage, Mandell notes, given that many users may harbor negative feelings towards anal and people who do it. (None of the condom manufacturers I reached out to for comment responded to me as of publication.)
Some inventors and start-ups want to make explicitly anal-oriented condoms, perhaps using new designs and materials, which would necessitate them investigating their anal efficacy. Origami condoms especially drew a good deal of hype in 2013 (but faded from the public eye after an alleged embezzlement scandal). However innovators sometimes complain that they have trouble generating the resources they need to conduct the studies necessary, as small firms trying to break into an established and relatively sclerotic market."
And if the studies proved there was a notably higher rate of failure in condoms for anal versus vaginal sex, Mandell adds, it could lead some to walk away from condoms altogether, even if they still offer more protection than nothing. “Is that,” he asks, “going to just harm people?”
Health experts outside of the worlds of condom manufacturing, like Johnson of the CDC, have tried to feel out the efficacy of condoms in anal sex as a matter of public health knowledge through less resource-intensive means. Usually, that means epidemiological studies monitoring how many people in a group contracted a given STI and examining their sexual behaviors, including condom usage. These studies suffer from all kinds of shortcomings, though, like self-reporting biases misrepresenting condom use rates, a lack of information on how many transmissions were due to slips and breaks and what factors in sex (e.g. lube type and amount or intensity of anal) led to those issues. More to consider: It’s hard to tell for some infections, like HIV, what type of sex led to a transmission.
Given the challenges of researching how condoms hold up in anal sex, especially when one has to control for murky factors like lube type and usage, intercourse intensity, and differences in individual anatomy—some people seem to have more resilient anuses than others—there is a good chance we may never fully understand how, and how much, anal affects them differently than vaginal play. These limits on our knowledge may make it hard, as Glickman points out, to know how useful anal-focused condom innovations would be, or even what kinds of innovations would be the most valuable. (A different material or design informed by anal tissue? A more secure base ring?) That is a problem for individuals currently working on developing condoms geared towards anal sex, especially in terms of their ability to generate support for their projects.
Still, Glickman stressed, “just looking at sexually transmitted infection rates, we do know that condoms are a net protection.” Using them for anal is far better than not using them. And we know enough, as Dieffenbach of the NIHAID points out, to say that any increased failure risks associated with anal sex can be mitigated by making sure one properly applies a condom and uses adequate lube. Granted, adequate lube is a subjective term, and some people may like or need more friction than others, or than is really safe. But as Dieffenbach says, “if it feels like it’s not going in easily, lubricate it.” In the end, he adds, “there is a common sense element to this.”
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