3 STIs you can catch even if you use a condom

This blog was originally published on 20/09/2021. Last updated 18/07/2025.

Condoms are one of the best tools you can use to stay safe during sex. They’ve been proven to lower the spread of sexually transmitted infections (STIs) and prevent unwanted pregnancies.

But condoms are just tools. And no tool works in every situation.

While you should always use a condom during sex if you’re worried about STIs, there are a few infections that might be able to slip through. Knowing what these infections are can help you protect yourself during future encounters.

Keep reading to find out more.

Worried about STIs? Order Better2Know’s Full STI Screen Home Test or get instant STI test results at a clinic.

What are condoms?

The main job of a latex condom is to prevent the transmission of bodily fluids such as semen, vaginal secretions, and blood. In turn, this can help to avoid pregnancy and STIs.

Using condoms correctly and consistently has been shown to reduce transmission of infections like HIV, Chlamydia, and Gonorrhoea by between 60%-85%.

When should they be used?

Vaginal and anal sex

Most condoms are used during vaginal sex between men and women. The condom is applied to the penis in order to protect the penis and vagina from absorbing infected bodily fluids.

Condoms can also be used during anal sex to prevent the spread of infections. Using condoms during anal sex is really important. Since the anus is more prone to tearing than a vagina.

If you’re receiving anal sex from your sexual partner and you get a tear, infected bodily fluids (especially those containing any bloodborne infections like HIV and Hepatitis B) will be more likely to establish an infection.

Oral sex

Some people also use condoms during oral sex. While the risk of transmitting STIs during oral sex is fairly low, it still poses a risk.

Oral STIs like Chlamydia, Gonorrhoea, Herpes, Syphilis, and HPV can all be transmitted during oral sex. Condoms, whether you’re giving oral sex or receiving oral sex, can make oral sex safer.

Sharing sex toys

When sharing a sex toy, infected bodily fluids can remain on the surface of the toy. If the toy isn’t washed thoroughly between uses, pathogens can linger and spread to the uninfected person who uses the toy.

Other methods of contraception

Condoms aren’t the only option for barrier methods of contraception. You can also use internal condoms and dental dams if these feel more comfortable for you.

So, whether you’re having oral, anal or vaginal sex and you’re worried about sexually transmitted diseases, it’s always a good idea to use a condom.

Can you get a sexually transmitted infection when you wear a condom?

While condoms are never a 100% guarantee against getting infected, many STIs are more likely than others to be transmitted.

Here are a few of them.

Molluscum Contagiosum

Molluscum Contagiosum is a fairly common skin infection that can cause round, firm, painless bumps that can appear anywhere on the skin.

These bumps, ranging in size from a pinhead to a pencil eraser, are typically skin-coloured, pink, or the same colour as your skin.

Molluscum Contagiosum spreads through skin-to-skin contact and contact with infected objects. Though most common in children, the virus can affect adults as well, and is often passed on through sexual contact.

Anyone who gets it shouldn’t be concerned. The virus is harmless, and any skin blemishes that result from it usually clear up between 6 months and two years.

Genital Herpes

Herpes Simplex Virus (HSV) can cause sores around the mouth, genitals or anus. HSV-1, or oral Herpes, causes cold sores or fever blisters commonly around the mouth and lips. HSV-2, or genital Herpes, causes sores to form usually around the genitals or anus.

Condoms have been shown to be very effective at preventing the spread of Herpes infections. However, condoms don’t always cover the area that is shedding the virus during an outbreak.

During an active outbreak (when you are most infectious), it is recommended to refrain from sexual activity in order to lower the risk of transmitting Herpes to your partner.

If you have an existing Herpes infection yourself, talk to your doctor about how you can practice safe sex. Try to avoid sexual activity if you’re having an outbreak.

Human Papillomavirus (HPV)

Genital Warts are caused by HPV – a family of viruses of which there are more than 140 different types. While Genital Warts are caused by low-risk types of the virus, high-risk types are associated with several different cancers.

HPV can be transferred through skin-to-skin contact with areas of the genitals that are not covered by a condom. Condoms have been shown to be effective in reducing the transmission of this virus; however, transmission is more likely to occur if the contact is repeated and prolonged, such as in a long-term relationship.

While some HPV infections can lead to Genital Warts and cancers, these infections are in a small minority. Most HPV infections cause no symptoms and are cleared by your immune system within a few months.

Even Genital Warts will go away on their own, eventually. Most cases of Genital Warts resolve within a couple of years.

Final thoughts

While condoms are a great way to prevent pregnancy and sexually transmitted infections, they can’t be successful every time. That’s why if you’re sexually active and think you may have been exposed to an STI, you should get tested.

We offer quick, convenient, and discreet STI testing at our local sexual health clinics in the UK. Call the number at the top of this page to book an appointment.

Don’t leave your sexual health to chance. Book your appointment today.

This article was medically reviewed by Dr. Steve Chapman, 06/11/2024

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