7 ways you can catch an STI without having sex

The more clued up you are about how infections can be contracted, the easier it is to know how to take care of your sexual health and keep yourself safe.

Kissing

Simple skin to skin contact can be enough to transmit some STIs. And kissing is no exception.

Lots of people catch Oral Herpes from kissing. People with Oral Herpes often develop cold sores around their mouth, which can spread the infection. The virus hunkers down in the nerve endings around your jaw, occasionally migrating to the surface of the skin, creating sores.

Some data also suggest that kissing can be a mode of transmission for Gonorrhoea, primarily between men who have sex with men.

Oral sex

Oral sex is, of course, a form of sexual contact. Because of this, it poses a higher risk of transmitting an infection. That’s because bacteria and viruses can penetrate the mucous membrane in the back of your throat.

Chlamydia and Gonorrhoea can easily be transmitted in this way. When you perform oral sex on someone with a bacterial infection in their genitals, infected bodily fluids transfer from the genitals to the mouth, thus creating the infection. An oral-to-genital infection, though, is incredibly rare.

Syphilis can also be transmitted from contact with an infectious chancre (Syphilis sores). However, the transmissions of Syphilis in oral sex more frequently pass the other way, when someone has a Syphilis infection in their mouth or throat performs oral sex. Using a condom during oral sex can help prevent catching STIs, but it will not provide complete protection.

Sharing toothbrushes, razors, or needles

Blood borne infections can spread by sharing objects which can cut the skin, with someone who is infected. This includes HIV, Hepatitis B, and Hepatitis C.

To minimise the risk, you should always avoid using another person’s toothbrush or razor and never share needles.

Blood transfusion

In the UK, blood used in transfusions is screened beforehand. However, if you had a blood transfusion before 1991 in the UK or at any time outside the UK, you may be at risk of bloodborne infections such as HIV and Hepatitis B.

Contaminated food

Hepatitis A can be spread through contaminated food or water. This is more common in developing countries with poor sanitation. Someone who gets a Hepatitis A infection through contaminated food or water can pass the infection on to another person through oral-to-anal sex, where faeces enter the mouth during sex acts like rimming.

Shigella is another bacteria that can be passed on during oral-to-anal contact. It produces gastroenteritis, but the infected faeces may be passed on during rimming.

Sharing sex toys

Unwashed sex toys can pass STIs between two or more people. This includes Chlamydia, Gonorrhoea, Trichomonas, Genital Herpes, and HPV amongst others. This is also the primary way Hepatitis C infections spread (anal-to-anal transmission).

It is important to clean your sex toys between use to prevent the spread of infection. You can read more about how to do so here.

If you want to avoid getting an STI while sexually active, you should practice safe sex by using barrier method contraception, such as condoms and dental dams. Unprotected sex is the main cause of new infections.

If you’re worried that you have a sexually transmitted disease, you should get tested as soon as possible. The sooner you know your sexual status, the better you can protect your health and the health of those you care about. Your sex life will be much improved for it.

This blog was published on 06/03/2020. Last updated 11/07/2025.

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