Blog & Events

Blog & Events

Back to blog posts

Mouth vs Butt

We spend a lot of time encouraging guys to cover their dicks with a condom when it’s going into a butthole, but when it comes to oral sex this is something that's talked about much less.

So why is wrapping it up for a blowjob not something you hear about as much?


We know that the risk of getting HIV from oral sex is extremely low for a few reasons – one is that HIV needs access to immune cells, to infect them and turn them into HIV replication factories. There is a very low level of access to these cells through the mouth and throat. Another reason is that saliva contains an enzyme (secretory leukocyte protease inhibitor) which breaks down HIV.

Oral sex does have risks for other STIs, especially the big two which are on the rise for gay and bi guys in NZ and around the world: syphilis and gonorrhoea. But there are a few reasons that condoms for oral sex haven't traditionally been promoted as much as for anal sex:

1. Biologically, oral sex has a lower transmission rate for most STIs

  • The mouth and throat are frequently exposed to environments outside of the body, so your body has evolved to be better at preventing and fighting off infections there than in your rectum.
  • Saliva has antimicrobial properties that can stop an infection establishing.
  • To top this off, cum in the mouth is fleeting, and might stick around for about three hours. In the rectum, even after bowel movements and post-sex douching, traces of semen can hang around for up to a week. This means the body is potentially exposed to an infection for a much longer time, which massively increases the chances that it will spread. Interestingly, semen and lube can continue to travel up the intestines from the anal canal after sex, almost reaching the small intestine within 24 hours!

2. Rectal STIs have less symptoms

After penile and vaginal STIs, those that manifest orally are among the most noticeable. Common symptoms include sores in the mouth, lesions (such as cold sores), and a painful throat that makes it difficult to swallow. Rectal STIs are generally much less symptomatic, and harder to find (because they’re hidden away up your butt). Even if you tried to look yourself, you’d have a very hard time finding anything that looked problematic. This means if you’re having anal sex without condoms, you need to be vigilant about regular testing for other STIs – including anal swabs, which you might have to ask for specifically, since many GPs don’t offer them as part of a regular check-up. And if you are using condoms for anal sex, you should also make rectal screening part of your annual STI check-up, because many STIs can also be passed on through fingering and rimming.

If you're having condomless anal sex, you should definitely look into getting the HPV vaccine, which is now free for guys in NZ under 26 years old.

3. HIV transmission rates increase when STIs are present

There are a few things to consider here:

  • Even with an STI, the risk of getting HIV from oral sex is still very low - it's anal sex without condoms when an STI is present that's the biggest concern.
  • If you are HIV negative and using PrEP, or having sex with a person living with HIV who has an undetectable viral load, your risk of acquiring HIV from condomless sex is extremely low. But we know that the presence of an STI can cause a spike in the viral load of a person living with HIV, if they aren’t on treatment. A higher viral load increases the risk of passing the virus on through unprotected sex (i.e. without condoms, PrEP or an UVL).

    We also know that according to recent studies, 1 in 15 gay/bi guys in Auckland are living with HIV, and of those, 1 in 5 are undiagnosed. So if you’re having sex with someone who says he’s HIV negative, there’s a 1.33% chance that he’s wrong (this may sound low, but when you think that over 1 in 100 gay/bi guys are living with HIV and don’t know it, this becomes more alarming).
  • If you’re on PrEP or using condoms, this doesn’t really affect you on an individual level. However, if a guy who doesn’t know he has HIV contracts syphilis from you, the resulting spike in his viral load means he has an even higher chance of transmitting HIV to anyone he is having unprotected sex with.

So while contracting syphilis might seem like it’s easily treatable and not too big a deal, it actually puts you at greater risk of contracting HIV, as well as boosting the level of risk for the whole community.

What this all boils down to is that if you’re on PrEP or have an undetectable viral load, it’s a good idea to keep condoms in the mix - especially if it's in the butt - and get tested for STIs regularly.

Latest Content

Latest Content

PRIVACY POLICY: The New Zealand AIDS Foundation (NZAF) recognises the importance of protecting your privacy. Any personal information that you provide to us, or authorise us to collect, will be collected and used in accordance with the Privacy Act and our Privacy Policy. For further information, please ask us for a copy or view the Privacy Policy now. You have the right to access and request correction of your personal information by contacting us using the details in our Privacy Policy.

The NZAF is passionately committed to working hand in hand with partners and the community to end HIV in New Zealand. By staying safe, testing often and treating early we can stop HIV in its tracks. Read more...

Supporting Organisations