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Oral sex
Historically, it has been very difficult to establish the contribution oral sex makes to overall HIV transmission since few people engage solely in oral sex. Instead, many people also have vaginal or anal sex, which are recognised routes of HIV transmission. Though there have been a number of cases of apparent HIV transmission via oral sex, health professionals have tended to prioritise HIV prevention efforts in the areas of greatest risk. This strategy may have inadvertently down-played the risks attached to oral sex, and left some individuals confused over risk reduction options.
How risky is oral sex?
The likelihood that HIV is transmitted from an HIV-positive person 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.
Oral sex has been shown to be a less risky activity than these practices, but is definitely not risk free. It’s also worth remembering that other sexually transmitted infections, such as syphilis, herpes and gonorrhoea, can be quite easily transmitted through oral sex.
In the past few years a number of studies have been published on the risks of HIV transmission from oral sex. One American study reported that of 122 gay men with HIV, 8% reported oral sex as their only risk activity. However, some of the men in this study who initially said oral sex was their only risk activity subsequently admitted having unprotected anal sex. A recent study didn’t find any cases of oral transmission of HIV over a ten year period in over 100 couples where one partner was HIV-positive and the other HIV-negative. Another study from the US found involving gay men found the risk to be effectively zero, but didn't exclude the possibility of there being a risk. The UK’s Public Health Laboratory Service estimates that between 1% and 3% of HIV cases may be due to oral sex.
When is oral sex more risky?
You are at more risk of passing on HIV through oral sex if you have an untreated sexually transmitted infection. You are at more risk of being infected with HIV from oral sex if you have cuts, sores or abrasions in the mouth or on the gums, or if you have an infection, including sexually transmitted ones, in the throat or mouth which is causing inflammation.
Viral load testing suggests that traces of HIV can almost always be found in semen. Having high viral load in the blood may also mean that viral load is high in the semen. The reverse is not necessarily true: even if viral load in the blood is undetectable, it may not be so in semen. Therefore it is not safe to assume that taking anti-HIV therapy always reduces the infectious potential of semen, or protects sexual partners.
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 advisor, or other health professional, at your treatment centre or genitourinary 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 sucking men or ‘dental dams’ (latex squares) for sucking women.
- You may decide only to have insertive oral sex (being sucked) as this appears safer than receptive oral sex (sucking).
- 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 with women during menstrual periods.
- Look after your mouth. The likelihood of oral HIV transmission increases if one has bleeding gums, ulcers, cuts or sores in the mouth. Don’t brush your teeth or floss before oral sex.
- Take 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.