Oral sex has a very low risk of HIV transmission. The virus can very rarely be passed on this way and only if the person with HIV has a detectable viral load.
What is the risk from oral sex?
Results from the PARTNER study show that if someone with HIV is taking effective HIV medication and has an undetectable viral load, they cannot pass on HIV.
According to Public Health England, around 1-3% of sexual HIV transmissions in the UK are because of oral sex. Other studies found that the risk is very low but is not zero.
Unprotected anal and vaginal sex leads to far more HIV infections than oral sex.
The risks are higher if the person giving oral sex has:
– cuts, sores or abrasions in their mouth or gums
– a sore throat or infection in the mouth or throat.
Or if the person receiving oral sex is:
– HIV positive
– has a detectable viral load
– has any cuts, sores or inflammation on the genital area.
Other sexually transmitted infections (STIs) such as gonorrhoea, chlamydia, herpes and syphilis can be passed on through oral sex.

Receiving oral sex from someone with HIV
Even if their viral load is detectable, this is considered to be an extremely low risk. Infection would really only be possible if someone with HIV was giving someone oral sex when their mouth was bleeding.
Performing oral sex on a man with HIV
There’s a potential risk if an HIV negative person performs oral sex on a man with HIV who has a detectable viral load.
This risk increases if a man’s infected pre-cum or semen gets into the other person’s mouth.
Avoid getting semen in your mouth – all but one of the cases where someone has been infected with HIV through oral sex took place when an HIV positive person with a detectable viral load ejaculated into their mouth.
Performing oral sex on a woman with HIV
This carries a very small risk, which can be cut by holding a latex barrier over the woman’s vagina.
Oral sex during a woman’s period carries a greater risk.
Reducing the risk from oral sex
The risk from unprotected oral sex with someone with a detectable viral load increases if you have:
– a throat infection (including an STI in the throat)
– damage to the lining of the mouth or throat
– had recent dental work or your gums bleed a lot.
Avoid performing oral sex without protection on someone with a detectable viral load while you have any of the above.
Don’t floss or brush teeth before oral sex (chew gum or rub toothpaste on your teeth instead). Regular check-ups for STIs will pick up infections in your throat.
By cutting down on the number of oral sex partners, you make the very small HIV risk even lower.
Remember that other STIs can also be passed on through oral sex, including herpes, gonorrhoea, chlamydia and syphilis.