Can you catch an STI even with a condom?

Reviewed by our clinical team

For people having sex with new or casual partners, condoms are really important. Not only do they prevent pregnancy, they also provide protection against STIs, including chlamydia and HIV.

However – despite their many benefits – condoms can’t offer 100% protection during sex, which is why it’s important to take other precautions, like getting tested for STIs. Read on to learn more.

How STIs spread

Sexually transmitted infections are usually either bacterial or viral, and can be spread during sex through the following bodily fluids:

• Semen
• Pre-cum – this is the fluid that comes out of the penis before ejaculation
• Vaginal fluid
• Blood
• Anal mucus

Usually, STIs carried in bodily fluids are passed from one person to another during vaginal sex or anal sex. This can happen even if ejaculation doesn’t occur inside the vagina or anus. 

Anal sex is particularly high-risk for the spread of STIs because the lining of the anus is thin and easily damaged, which means it’s more vulnerable to infection than other parts of the body.

STIs carried in bodily fluids can also be spread during oral sex, especially if you or your partner have any sores or cuts around the mouth, genitals or anus. Other risky activities include fingering and sharing sex toys. 

Skin-to-skin contact

Some STIs spread through skin-to-skin contact. If you have sex with someone who has genital warts or genital herpes, you can become infected just through contact with their skin. 

How condoms protect you during sex

Using male or female condoms during sex protects you from STIs because they create a physical barrier between yourself and your partner, and prevent the mingling of bodily fluids. This is why condoms work as contraception too.

With STIs that are spread through skin-to-skin contact, condoms can be helpful in a slightly more limited way. Areas of the skin covered by the condom will be protected, but those uncovered may still be vulnerable to infection with the genital warts or genital herpes virus. 

In general, though, condoms will hugely decrease your risk of getting an STI. This is why you should always use them if you’re having sex with a new or casual partner i.e. someone who might have an STI. 

Condoms can be used for:

• Vaginal sex
• Anal sex
• Oral sex
• Sharing sex toys 

In addition to condoms, you can stay safe by stocking up on dental dams and latex gloves. Dental dams are thin, flexible squares of plastic that you can put over your partner’s genitals or anus during oral sex. Latex gloves can be used for fingering and fisting. 

I use condoms but I still got an STI. How did this happen?

The condom broke

Condoms are strong but they can break if they’re not put on correctly, or if they’re used in the wrong way. 

Be careful not to tear the condom with your fingernails or snag it on jewellery when taking it out of the packet, and make sure you put it on the right way. If you get it wrong the first time, throw the condom away and get a fresh one. Guidance on using condoms correctly can be found at the NHS website. Or you can read our guide on wearing condoms. 

It’s also a good idea to check the use-by date on your condoms, as they can expire. 

You used an oil-based lubricant

Oil-based lubes might feel good but they can weaken the latex used to make most standard condoms, and this can lead to breakage. Examples of oil based lubricants are coconut oil, olive oil, Vaseline, many body lotions and moisturisers. To avoid this, use water-based lubricants, such as a dedicated “pleasure gel” or “sex lube”. Saliva is a great natural lubricant that’s free and always available.

The condom was put on too late

It’s not uncommon for people to dislike the feel of condoms, and to therefore try and use them for as short a period as possible. The problem with this is that STIs can spread even before ejaculation occurs. Male condoms should be put on once the penis is erect but before touching the other person’s genitals. 

The condom was taken off too late

Another mistake people make with male condoms is taking them off too late. A male condom should be removed while the penis is still erect, as this prevents semen from leaking out.

You picked up an STI when you weren’t having penetrative sex

Even if you use condoms for vaginal and anal sex, you can still be vulnerable to STIs if you don’t use protection for other types of sex. To stay safe, it’s a good idea to use condoms for oral sex and sharing sex toys. 

You can also protect yourself and your partner by using dental dams and latex gloves for activities like oral sex and fingering. These precautions are especially important if you have cuts or sores on your mouth, genitals or hands (5).

You picked up an STI that spreads through skin-to-skin contact

As we’ve highlighted, not all STIs require the mingling of bodily fluids or penetrative sex to spread. Intimate touching of the genitals – with or without a condom – can sometimes be enough to spread STIs like genital warts and genital herpes.

Getting tested for STIs

If you use condoms your risk of catching an STI will be low. However, you should still get tested for STIs if you’re having sex with new or casual partners. For most people, an annual STI check-up should be sufficient – for people with a higher risk of getting an STI, more regular checks might be necessary.

Getting tested is important as many STIs don’t cause any symptoms in their early stages. When left untreated, some STIs can lead to chronic pain, and/or infertility.  If you catch HIV and it’s not detected or treated, it will usually progress to late-stage HIV (AIDS) in the vast majority of people.  AIDS means that that your immune system has been severely damaged, and it can no longer fight infections. Some of these infections can be life threatening, and not all of them can be treated successfully.

You can get tested for free at sexual health/GUM clinics, or – as an alternative – you can order a home test kit through a trusted service like Online Doctor. Click here to find out how our home test kits work.

References

https://www.nhs.uk/live-well/sexual-health/sex-activities-and-risk/
https://www.tht.org.uk/hiv-and-sexual-health/about-hiv/how-hiv-transmitted
https://www.nhs.uk/conditions/genital-warts/
https://www.nhs.uk/conditions/genital-herpes/
https://www.nhs.uk/live-well/sexual-health/sexual-health-for-lesbian-and-bisexual-women/
https://www.avert.org/about-hiv-aids/symptoms-stages