What Is a Condom?

Disposable Barrier for Birth Control and STD Prevention

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A condom is a thin, disposable, sheath-shaped barrier used during different types of sexual activity in order to reduce the risk of pregnancy and sexually transmitted diseases (STD). Some condoms are designed to be used on a penis, while others are worn inside the vagina/front hole. Condoms must be used correctly in order to be effective.

Types of Condoms

There are two main categories of condoms, based on the wearer's genitalia:

  • External condoms: Are worn over the penis to collect ejaculate fluids.
  • Internal condoms: Are worn inside the vagina/front hole or anus and prevent ejaculate fluids, including semen, from entering. They tend to be more expensive than external condoms.
Regular condom and internal condom
Lalocracio / iStock / Getty Images

How a Condom Works

A condom works by creating a barrier between a penis (or sex toy/dildo) and a vagina/front hole, anus, or mouth, for the purpose of preventing pregnancy and/or sexually transmitted infections.

A condom worn correctly on a penis ensures that ejaculate fluids are not passed along to a sexual partner during vaginal, anal, or oral sex. Internal condoms have rings on each end. One is placed inside the vagina/front hole and fits over the cervix, covering it. The other ring is open and sits outside, covering the vulva. If using an internal condom for anal sex, the inner ring of internal condom should be removed.

When used regularly and correctly, both external and internal condoms are effective at reducing the risk of sexually transmitted infections like HIV, HPV, chlamydia, gonorrhea, genital herpes, and syphilis, as well as other conditions that can be spread through sexual contact, like the Zika and Ebola viruses.

As far as pregnancy, external condoms can be up to 97% effective if they are used correctly and every time a person has sex. Internal condoms are up to 95% effective when they are used correctly and consistently.

Unfortunately, the failure rate for pregnancy prevention for typical condom use is 13% for external condoms, and 21% for internal condoms, making it very important to ensure you are using them properly every single time. 


In addition to reducing the risk of pregnancy and sexually transmitted infections during vaginal or anal sex, condoms can also be used to make oral sex and sex toy use with a partner safer.

Though you’re less likely to receive or pass along HIV or other sexually transmitted infections through oral sex than you are through penetrative sex, the risk is still present. It is possible for other STIs, like herpes and HPV, to spread through oral sex as well.

To make oral sex safer, recipients who have a penis can wear a condom. In situations involving performing oral sex on an anus (also known as “rimming”) or a vagina/vulva/front hole, an external condom can be cut into a square to create a barrier. Dental dams are another option, and already come in sheets.

If you’re sharing a sex toy with a partner—particularly a dildo, vibrator, or other device that is inserted—you should use a new condom for each person, and wash the toy between uses.

Condoms and Consent

In terms of consent, if both partners agree to use a condom during sex, that typically comes with the understanding that the person wearing the condom will keep it on the whole time.

If a person removes a condom mid-sex without getting approval from their partner first—sometimes referred to as “stealthing”—the sex is then considered non-consensual and a type of sexual assault. 

Advantages and Disadvantages

Like any form of birth control or safer sex, there are both advantages and disadvantages to using condoms.

Some of the advantages of condoms include:

  • They reduce the risk of pregnancy and sexually transmitted infections. 
  • They do not involve hormonal treatments.
  • Condoms do not affect fertility and are not a permanent form of birth control.
  • They are relatively inexpensive and often given away for free at medical facilities, universities, and as part of public health campaigns.
  • Condoms do not require a prescription and are readily available from pharmacies, supermarkets, big box stores, and vending machines.

Some of the disadvantages of condoms include:

  • There is a potential for user error.
  • It is possible to have manufacturer defects (though they are rare).
  • They can tear while in use.
  • Many condoms are made out of latex and could cause a reaction in those allergic to latex. There are latex-free condoms.
  • The condom may cause additional friction during sex, resulting in irritation (though that can be alleviated by using lube). 

History of Condoms

Condom use has been recorded as far back as 3000 BC when a Bronze Age Greek king was said to have used a goat’s bladder to prevent spreading infectious diseases to his wife and mistresses.

Other ancient civilizations, including those in Rome and Egypt, also used animal bladders and intestines as condoms, as well as sheaths made of linen. Other early condoms were made from fish, silk, or certain plants.

These materials remained the standard for condoms until the 19th century when the vulcanization of rubber was first utilized, allowing them to be manufactured on a much larger scale, beginning in 1860. Latex was invented in the 1920s and has been used to make condoms ever since.

Medical Significance

Condoms continue to be an important public health prevention tool, decreasing the risk of unplanned pregnancy and sexually transmitted infections. And though they’ve been used for thousands of years, awareness of condoms increased in the 1980s when it was discovered that HIV/AIDS was sexually transmitted.

Since then, condoms have become a regular part of sexual education (except in abstinence-only curricula) and widely available in North America. More recently, condom use has also been encouraged as a way to reduce the risk for genital human papillomavirus (HPV) infection and HPV-associated diseases like cervical cancer.

A Word From Verywell

Condoms are an important part of sexual and reproductive health for people of all gender and sexual identities, providing an accessible tool for safer sex. Like any other aspect of sexual negotiation, partners should discuss how and whether to incorporate condoms into their sexual practice, keeping in mind that they can be used for penetrative and oral sex, as well as in cases where sex toys are being shared.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Condom fact sheet in brief.

  2. Vorvick LJ. Condoms - male. MedlinePlus.

  3. Vorvick LJ. Female condoms: MedlinePlus Medical Encyclopedia. MedlinePlus.

  4. Centers for Disease Control and Prevention. Contraception.

  5. U.S. Department of Veterans Affairs. Tips for using condoms and dental dams.

  6. Khan F, Mukhtar S, Sriprasad S, Dickinson I. The story of the condom. Indian J Urol. 2013;29(1):12. doi:10.4103/0970-1591.109976

  7. Centers for Disease Control and Prevention. Condom fact sheet for public health personnel.

By Elizabeth Yuko, PhD
Elizabeth Yuko, PhD, is a bioethicist and journalist, as well as an adjunct professor of ethics at Dublin City University. She has written for publications including The New York Times, The Washington Post, The Atlantic, Rolling Stone, and more.