To pass on HIV, you would first need to have a detectable viral load. If you’re keeping up with your medication and you have an undetectable viral load, which you’ll know from clinic appointments, you will NOT be able to pass on HIV during sex, even if you had unprotected sex. This is called U=U, undetectable means untransmittable.* And passing on HIV any other way would be unlikely.
Even if you have a detectable viral load, to pass on HIV there must be a direct way for the virus to get into another person’s blood stream, a bit like going through a door. You cannot get HIV from kissing, cuddling, or sharing drinks, plates or toilet seats.
Ways you can contract HIV
Semen, vaginal fluids, and anal mucus
If a person living with HIV with a detectable viral load has sex without a condom, HIV can get into the other person’s blood because it lives in semen, vaginal fluid, and anal mucus. Anal sex is the riskiest kind of sex for passing on or contracting HIV because the rectum’s lining is very thin.
Using condoms can stop any fluid being passed between sexual partners, and they also prevent unplanned pregnancies and any other sexually transmitted infections.
Blood
HIV can’t survive for long outside the body. Even if someone with HIV cuts themselves and another person comes into contact with their blood, the risk of transmission is very low. Unless the other person has a cut or broken skin at the same time, there is no risk of passing the virus on.
If you cut yourself, wash any blood away with soap and hot water and cover the wound with a sticking plaster or dressing.
In the past, many people got HIV through blood transfusions, where HIV-infected blood was put straight into someone else’s bloodstream. But this was before it was known how the virus was passed on. In most countries, blood is now checked thoroughly before it is donated to other people.
Needles
If one person living with HIV injects themselves with a needle, and another person injects themselves with the same needle directly afterwards, they can contract HIV. So sharing needles is not advised. This is how a character on Eastenders contracted the virus.
Vertical transmission
HIV can be passed from a mother (or birthing parent) living with HIV to a baby whilst they are growing in the womb or during childbirth. This is known as vertical transmission. If you have lived with HIV since birth, this may help you understand how you acquired it.
There are now several steps taken to help stop a baby being born with HIV:
- Women living with HIV take medication during pregnancy
- Additional care is given to the mother during labour
- The baby is given preventative HIV medication (PEP) in the first few weeks after birth
These steps work so well that there is now a less than 1% chance of HIV being passed from mother to baby in the UK.
Breast milk
HIV can also be found in breast milk, and can sometimes be passed on to a baby when they are feeding. Mothers (or birthing parents) living with HIV in the UK are advised not to breastfeed, unless it has been approved as safe by a medical professional. Mothers with an undetectable HIV viral load may choose to breastfeed with support from medical teams.
Find more here:
BHIVA: HIV and breastfeeding your baby
BHIVA: General information on infant feeding for women living with HIV.
Chiva: Should mothers living with HIV breastfeed their babies?
NOURISH-UK Choosing how to feed your baby while living with HIV: A new resource
U=U
*U=U stands for undetectable = untransmittable. It’s become a popular phrase used in HIV awareness campaigns.
You are undetectable if:
- You are taking your antiretroviral therapy (HIV meds) and have such low levels of HIV in your blood that it is ‘undetectable’ in a blood test.
- Your HIV has been ‘asleep’ for more than six months
- You are having regular HIV viral load blood tests and haven’t missed any doses of medicine since your last blood test.
If you are undetectable this means you can live a long and healthy life and there is NO way you can pass on HIV to a sexual partner. It is ‘un-transmittable’.
How do we know this?
From a clinical trial called The Partner Study. It followed more than 1000 couples, where one partner was living with HIV and the other was HIV negative. The partner living with HIV was on antiretroviral therapy and their viral load had been suppressed for more than six months. The couples lived across Europe and included gay and straight couples.
Over several years the couples had sex, without using a condom, more than 58,000 times. There were zero transmissions of HIV.
This proved that if you live with HIV and take your medication as instructed, you are not infectious. You will not pass HIV on to your sexual partners, even if you don’t use a condom or if it splits or falls off.
Do I still need to use a condom?
We still advise those living with HIV to use condoms because:
- They stop you catching other sexually transmitted infections such as chlamydia and gonorrhoea
- They help prevent unwanted pregnancies. Even if you are using condoms, you may want to use an additional method of contraception, just to be safe.
Find out more about contraception and HIV, including how it might interact with your meds, in our information sheet.
You can read more about U=U in this factsheet from I-Base.
