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Oral sex

Michael Carter, Greta Hughson
Published: 25 September 2012

Many men and women find oral sex an intensely pleasurable experience. People use different terms to refer to oral sex (including formal terms like fellatio and cunnilingus and slang terms like blow jobs and giving head). Usually oral sex means one person kissing, licking or sucking another person's genitals.

Oral sex and HIV

Doctors and researchers can't be sure how many people have been infected with HIV through oral sex. Some think hardly anybody has been infected with HIV from oral sex, but other people think that as many as 3% of infections are due to oral sex. In late 2008, researchers looked at all the available evidence and calculated that the risk of contracting HIV from oral sex was very low, but that it wasn't zero.

It is known that oral sex involves less risk than unprotected anal sex or unprotected vaginal sex.

The likelihood that HIV is transmitted from a person with HIV to an HIV-negative person depends on the type of contact involved. HIV is most easily transmitted by unprotected anal sex (that is, without condoms), unprotected vaginal sex, sharing injecting equipment, and from mother to baby. It also depends on the viral load of the person with HIV.

Oral sex has been shown to be a less risky activity, but it is not risk free. Again, it depends on the viral load of the person with HIV and the dental health of the person performing oral sex. It’s also worth remembering that other sexually transmitted infections, such as syphilis, herpes and gonorrhoea, can be quite easily transmitted through oral sex. If you don't use condoms, or dental dams, for oral sex, it's a good idea to have regular sexual health check-ups.

The risk of HIV being passed on during oral sex centres on fluid containing HIV (semen, vaginal fluid or blood) finding a way into the bloodstream of an HIV-negative person (via the mouth or throat, which is more likely if there is inflammation, or cuts or sores present). HIV is not passed on through exposure to saliva alone, so a person with HIV performing oral sex on someone who is HIV negative is considered to be very low risk.

The type of oral sex makes a difference to the level of risk.

  • HIV transmission through 'receptive fellatio', which means an HIV-negative person performing oral sex on (giving a blow job to) a man with HIV is possible and it is likely that HIV transmission happens in this way sometimes.
  • HIV transmission through 'insertive fellatio', which means an HIV-negative man receiving oral sex from a person with HIV, is very low risk and may be impossible.
  • There have been very few reports of possible HIV transmission through cunnilingus (oral sex performed on a woman). It is biologically possible that HIV could be passed on through an HIV-negative person performing oral sex on a woman with HIV, but this is considered to be low risk.
  • There have been no documented cases of someone being infected with HIV through receiving cunnilingus from a woman with HIV.

When is oral sex more risky?

If you have HIV, there is a higher risk of passing on HIV through someone performing oral sex on you, if you also have an untreated sexually transmitted infection. If you don't have HIV and you are performing oral sex on someone who does have HIV, you are at more risk of being infected if you have cuts, sores or abrasions in your mouth or on your gums. There is also more risk if you have an infection, including sexually transmitted ones, in your throat or mouth which is causing inflammation.

For men, having a high viral load in the blood may also mean that viral load is high in the semen. Although there is good evidence that men who have an undetectable viral load in their blood usually have an undetectable viral load in their semen, this isn't always the case. Factors like untreated sexually transmitted infections can cause viral load in semen to increase. Therefore, most doctors believe you cannot assume that having an undetectable viral load means you're uninfectious. However, the risk of HIV transmission during oral sex if a person has an undetectable viral load is extremely low.

For women, the levels of HIV in vaginal fluid vary. They are likely to be highest around the time of menstruation (having your period), when HIV-bearing cells shed from the cervix are most likely to be found in vaginal fluid, along with blood. Oral sex will therefore be more risky around the time of menstruation.

How can you reduce the risks?

There are several ways to reduce the risks of oral sex. Naturally, some will be more acceptable than others to different individuals, so you must make your own decisions about the level of risk you find acceptable. If you would like to discuss these issues, ask to see a health adviser, or other health professional, at your treatment centre or sexual health clinic. Many of the strategies below will also provide protection against other sexually transmitted infections:

  • You may decide that the risks of oral sex are low enough for you to continue your regular behaviour.
  • You may prefer not to have oral sex because you do not wish to take even a low risk of HIV transmission.
  • You may decide to reduce the number of partners with whom you have oral sex.
  • You may decide to have oral sex with barriers such as condoms for men or dental dams (latex squares) for women.
  • If you don't have HIV, you may decide only to have insertive oral sex (someone giving you oral sex) as this is safer than receptive oral sex (giving someone else oral sex).
  • You may decide not to ejaculate into your partner’s mouth or not to have someone ejaculate into your mouth.
  • You may decide to avoid oral sex during menstrual periods.
  • Look after your mouth. The likelihood of becoming infected through giving oral sex increases if someone has bleeding gums, ulcers, cuts or sores in the mouth. Don’t brush your teeth or floss just before oral sex.
  • Have regular sexual health screening. This will identify if you have any sexually transmitted infections, which may increase the likelihood of you transmitting HIV to a negative partner, and reduce the likelihood of you contracting HIV if you are HIV-negative.

Find out more

For more information on oral sex and sexual transmission of HIV, you may find the information in our publications HIV & sex or HIV transmission & testing helpful. Online versions of these are freely available in the resources section of our website: www.aidsmap.com/resources.

Contact NAM to find out more about the scientific research and information used to produce this factsheet.

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.