Sex Ed

Why “Safe Sex” Isn’t Quite As Safe As You Think

August 19, 2013 by Justin Lehmiller


Although “safe sex” means different things to different people, the most common thing people associate with this term is the male condom. We have been told time and again by sexual health educators and condom manufacturers alike that condoms can be highly effective at preventing unintended pregnancies and sexually transmitted infections (STIs)—and there is no disputing that. However, research has found that people tend to overestimate how effective condoms are in practice [1] and for that reason, it is important to step back and look at what condoms do and don’t do, and reconsider our usage of the term “safe sex.”

One of the reasons people overestimate the effectiveness of condoms is due to the widely cited statistic that condoms are 98% effective at preventing pregnancy. Although this statistic is indeed accurate [2], it is based upon the assumption of perfect use (i.e., that heterosexual couples use condoms all of the time and that they never make any mistakes); however, it is not wise to assume that condoms will always be used perfectly. As I have written in other articles, condom use errors occur frequently and include putting the condom on too late or removing it too early, using incompatible lubricants (e.g., oil-based lubes with a latex condom), and accidentally puncturing the condom with sharp objects. In addition, men frequently report problems finding condoms that fit well, which increases the likelihood of breakage and slippage. As a result, when you factor in human error and other condom problems, the actual (i.e., typical use) effectiveness rate for pregnancy prevention drops to 82%, which is only marginally better than the 78% effectiveness rate of the withdrawal (i.e., “pull and pray”) method [2]! It is important that you don’t let perfect use rates lull you into a false sense of security. For condoms and other contraceptives, pay more attention to those use rates, which tend to be a bit lower and are more reflective of reality.

How effective are condoms at preventing STIs? Unfortunately, that’s a much harder question to answer because it’s not like we can order a bunch of uninfected people to have sex with infected partners and see how many times diseases are transmitted. That said, lab studies tell us that condoms serve as very effective barriers to the passage of infectious organisms (see here for a list of relevant studies compiled by the CDC). Also, consider that studies of romantic couples in which one partner has HIV and the other doesn’t have shown that when the infected partner is on medication and the couple uses condoms, the risk of infection transmission is near zero [3]. However, lab studies don’t reflect what happens in the real world (i.e., condom use errors), and studies of romantic couples probably aren’t generalizable to people having casual sex because people who love each other will probably put more effort into making sure that condoms are always used (and that they are used correctly).

Also, when you consider the fact that STI organisms are even smaller than sperm cells, that certain infections can reside on the skin in areas that are not covered by condoms (e.g., herpes, HPV), and that STIs can potentially be spread during virtually any sexual activity (i.e., not just vaginal intercourse), the effectiveness of condoms at preventing STI transmission is likely quite a bit lower compared to preventing pregnancy. Moreover, the pregnancy prevention rate is artificially inflated to begin with by the fact that pregnancy cannot always occur, given that women are not constantly ovulating. What this means is that even if no method of pregnancy prevention is employed over the course of a year, 100% of women will not become pregnant—only 85% will because sexual encounters are not always timed with peak fertility [2]. In contrast, STIs can be spread no matter what time of the month it is.

What all of this means is that when we talk about condoms as representing “safe sex,” we’re not being very precise and we are feeding into the false perception that condoms guarantee safety. It is important that we start teaching people that just because condoms are used does not make sex inherently “safe”—sex just becomes safer than it otherwise would have been. Thus, it would probably be wise to think about condoms as a form of “safer sex.”

The point of this article is not to frighten or scare anyone away from sex; instead, the goal is to make sure that you have appropriate expectations for the level of protection you can expect from condoms and to provide advice on what you can do to reduce risks for you and your partner(s) even further. To that end, it is important for everyone who is sexually active to recognize that condoms are imperfect devices. This means that STI testing isn’t something that should be reserved only for cases in which you didn’t use a condom or the condom broke—you can still potentially get STIs even if you use condoms correctly every time. Also, don’t put off testing until you notice something wrong because not all STIs have immediate symptoms (e.g., gonorrhea, chlamydia, HIV). In other words, using condoms and being symptom free is not a substitute for visiting the doctor every now and then. If you’re sexually active, and especially if you or your partner have multiple partners, you should be getting tested at least occasionally.

In addition, be sure to stockpile some condoms so that they are around when you need them. However, brush up on the basics of proper condom use first (see here or here) and remember that, contrary to popular belief, condoms (like Twinkies) have expiration dates and aren’t good forever—so you will need to replenish and replace every now and then. Also, if you’re concerned about pregnancy prevention, consider using more than one method of protection (e.g., condoms plus birth control pills) so that you can further reduce the risk of unintended pregnancy while still taking advantage of condoms’ unique ability to reduce the risk of STIs.

Finally, be sure to communicate with your partner. Ask your partner about their STI status and how recently they were tested, and be ready to reveal the same information about yourself (and be sure to do so honestly!). I know this is easier said than done and that talking about STIs isn’t very sexy—but remember that giving and getting STIs isn’t very sexy either. On a side note, isn’t it odd that our society has deemed talking about sex to be more personal and intimate than actual sex act itself? This is one social convention that needs to be broken.

In short, if you’re going to be sexually active, you have to accept some degree of risk; however, there is a lot you can do to minimize those risks and this starts by recognizing that there’s no such thing as “safe sex”—there’s just safer and smarter sex.

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[1] J. E., Zhao, Q., & Piepert, J. F. (in press). Knowledge of contraceptive effectiveness. American Journal of Obstetrics and Gynecology.

[2] Trussel, J. (2011). Contraceptive failure in the United States. Contraception, 83, 397-404.

[3] Attia, S., Egger, M., Müller, M., Zwahlen, M., & Low, N. (2009). Sexual transmission of HIV according to viral load and antiretroviral therapy: Systematic review and meta-analysis. Aids, 23, 1397-1404.

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Written by
Dr. Justin Lehmiller
Founder & Owner of Sex and Psychology

Dr. Justin Lehmiller is a social psychologist and Research Fellow at The Kinsey Institute. He runs the Sex and Psychology blog and podcast and is author of the popular book Tell Me What You Want. Dr. Lehmiller is an award-winning educator, and a prolific researcher who has published more than 50 academic works.

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