What’s the truth about infections and oral sex?

Many young people are searching online for information about whether oral sex can cause things like tonsillitis, bad breath, tooth infections and cancer. But these are all myths. 

That doesn’t mean oral sex is risk free. It can cause some sexually transmitted infections (STIs). So it’s important to know the facts. 

Which infections ARE NOT caused by oral sex? 

First, let’s bust the myths. 

Whether you are giving or receiving oral pleasure to the genitals or anus, it is not possible to get any of these infections through oral sex. 

Can oral sex cause tooth infections? 

Some STIs like herpes and chlamydia can cause sores in your mouth or give you gum problems. But they won’t give you a tooth infection.  

If you get a tooth infection it will not be directly caused by an STI. Not brushing or flossing your teeth well enough is the most common cause of tooth infections as this allows plaque (bacteria) to build up.  

Can oral sex cause bad breath? 

STIs do not directly cause bad breath. But they can cause sores and mouth ulcers, which sometimes release a bad smell.  

Dehydration (being thirsty), poor dental hygiene or a bacterial imbalance are the most common causes of bad breath. But if you have sores or ulcers that won’t go away, it might be worth taking an STI test. 

Can you get tonsillitis from oral sex? 

STIs cannot cause tonsillitis. But it is possible for some STIs (like gonorrhoea and chlamydia) to cause symptoms like swollen and sore tonsils, which you might mistake for tonsilitis.  

If you have a sore throat that you cannot shake off, it could be a sign of an STI. If this happens, it is a good idea to test for STIs and get your throat checked.

Can you get cancer from oral sex? 

Oral sex cannot cause cancer. But it can put you at risk of HPV. And HPV can cause some types of cancer if left untreated.  

If HPV infects the mouth and throat there is a small chance it could cause throat cancer. But it usually takes years after being infected with HPV for throat cancer to develop, and most people’s HPV infection clears up long before this. 

Which infections ARE caused by oral sex? 

The following things can easily be passed on during any type of oral sex. 

Can you contract herpes from oral sex?  

Yes – herpes can be passed on through cuts or break in the skin around the mouth and genitals. This means it is easily passed on through oral sex. 

If either you or your partner has a herpes outbreak (blisters) it is best to wait until the symptoms have cleared up before having oral sex, or any other kind of sex. 

Can you get chlamydia from oral sex? 

Yes – gonorrhoea and chlamydia can be passed on if someone’s lips, mouth, throat or genitals comes into contact with any semen, blood or vaginal fluids carrying either infection.  

One of the trickiest things about chlamydia is that it usually has no symptoms, meaning most people with the infection do not know they have it. This is often true for gonorrhoea as well. That’s why it is important to regularly test for STIs so you know your status.  

Can you catch syphilis from oral sex?  

Yes – syphilis can cause sores or rashes to the genitals, anus, lips, rectum or inside the mouth. You can get syphilis if you come into contact with these sores. And this can happen if you have oral sex.  

Syphilis is not as common as some STIs, but if it is left untreated it can lead to serious health problems. If you or your partner has a sore or rash, it is a good idea to get tested – then you can get treatment if you need it. 

Can you get HPV from oral sex?  

Yes – HPV and genital warts spread through skin-to-skin contact, including through oral sex. HPV is very common and nearly everyone will get some form of HPV at some point in their life. 

There are many different strains of HPV. Most have no symptoms, go away by themselves and don’t cause any health problems. But some types can cause genital warts or lead to cervical, anal and other cancers, so it is important to get regularly checked for it. 

Can cold sores spread during oral sex? 

Yes – if someone has a cold sore, they can still spread it to a partner’s genitals through kissing or skin contact. This includes through oral sex. So if either you or your partner has a cold sore, it is best to wait until it has cleared up before getting passionate.  

The following things are less likely to be passed on, but there is still a risk. 

Can you get HIV from oral sex?  

The risk of passing on HIV through oral sex is low, unless the person receiving oral sex has an STI, or genital sores. Or the person giving oral sex has mouth sores or bleeding gums. But if someone is on HIV treatment and undetectable, they cannot pass HIV on, including through oral sex. 

Can you catch genital infections from oral sex? 

Yes – although it is unlikely. Although neither is an STI, there is a small risk of passing on a urinary tract infection or bacterial vaginosis through oral sex. If someone has a yeast infection (thrush), there is also a small risk of passing it on through oral sex because the fungus that causes thrush can also grow in the mouth. 

Can you get hepatitis A from oral sex? 

Yes – some infections and viruses found in faeces (poo) can be passed on through anal-oral sex, particularly hepatitis A and E.coli. 

How to have safe oral sex 

The good news is you can have oral sex in a low-risk way if you use the right protection. 

• Use a condom for oral sex on a penis.
• Use a dental dam for oral sex on a vagina or anus. You can learn more about dental dams on our oral sex page. 

Other things you can do to reduce the health risks of oral sex:   

• Don’t brush your teeth just before oral sex as this can make your mouth or gums bleed. You can use a gentle mouthwash though.
• Avoid getting semen (cum) or vaginal fluids in your mouth.
• Wash your genitals or anus afterwards as this can reduce the bacteria that can cause an infection.
• Avoid oral sex if either you or your partner has sores around your mouth, genitals or anus, bleeding gums, or a throat or mouth infection. 

Remember that you may not know if you or your partner has an STI. This is because sometimes an STI will not cause any symptoms. That’s why getting regular STI tests is so important. 

If you want to talk to a partner about having safer oral sex, the tips on our oral sex page (on the ‘in detail’ tab) can help.