How likely am I to get HIV based on the act?

Key points:

You’re more likely to get HIV through unprotected sex, especially through receptive anal sex
While possible, vaginal sex is unlikely to transmit the virus, especially if you use protection
You can’t get HIV by hugging, kissing, or biting an infected person

HIV can be one of the more challenging sexually transmitted infections someone can get. While advancements in treatment over the years have ensured people infected with HIV can live a long time, it often requires constant treatment and vigilance.

So, if you can avoid getting it, you should.

Keep reading to find out more about how HIV transmits so you can better protect your health.

A person looking out a window

AI-generated content may be incorrect.

Find out your HIV status from home with one of Better2Know’s Home Test Kits.

Get tested

What is HIV?

HIV, or Human Immunodeficiency Virus, is a virus that targets the immune system—specifically the CD4 cells that help your body fight off infections.

If left untreated, HIV gradually weakens the immune system, making it harder to fend off everyday illnesses and infections. Over time, this can lead to AIDS (Acquired Immune Deficiency Syndrome), which is the stage where the immune system is severely compromised.

But here’s the good news: with early detection and proper treatment, people living with HIV can lead long, healthy lives with a normal life expectancy.

How is HIV transmitted?

You can get HIV in a few ways – and not just through sex. Below you’ll find a variety of acts and how likely you are to get HIV from them. All statistics presented here are gathered and approved by the Centers for Disease Control in the US.

Sexual acts

The vast majority of HIV infections occur from unprotected sex. But some sex acts are riskier than others.

(NOTE: The descriptions below describe sex acts where risk isn’t mitigated by things like condom use, male circumcision, antiretroviral therapy, and pre-exposure prophylaxis, all of which will reduce the likelihood of transmission.)

Vaginal sex

Unprotected vaginal sex is very unlikely to transmit HIV.

For every 10,000 exposures, receptive vaginal sex (ie a woman having sex with an infected man) will only result in around eight infections.

Insertive vaginal sex (ie a man having sex with an infected woman) is even less likely, with only 4 out of every 10,000 exposures likely to result in infection.

While vaginal sex remains an unlikely route of transmission, it can be made more likely if the uninfected partner already has an existing STI like Chlamydia or Gonorrhoea.

Anal sex

Anal sex poses the most considerable risk of passing on HIV because of the biological structure of the anus and rectum.

The lining of the rectum is thin and fragile, making it prone to tears during intercourse. These tears provide direct access for pathogens like HIV to enter the bloodstream, especially if the infected person has HIV and is not receiving treatment.

The risk is different depending on the sex act and who is infected.

In receptive anal intercourse, 138 out of every 10,000 exposures is likely to result in infection. In insertive anal intercourse, the likelihood drops to 11 of every 10,000.

Oral sex

While technically possible, the likelihood of transmitting HIV through oral sex is so low that most health professionals consider it a negligible risk.

For transmission to happen, something very unusual would have to occur. For example, an infected person ejaculating into the mouth of someone with mouth ulcers, bleeding gums, or the presence of another STI may slightly increase the odds.

Sharing sex toys

HIV doesn’t survive long outside the human body, which means the virus becomes inactive fairly quickly once exposed to air or surfaces.

However, if the toy is used in quick succession between partners, especially without cleaning or changing condoms, the virus may still be viable enough to pose a risk.

Using non-porous toys (like those made from silicone or stainless steel), cleaning them thoroughly between uses, and using a fresh condom for each person are all effective ways to reduce the risk.

While technically possible, transmission of HIV through sharing sex toys hasn’t been studied sufficiently, and more research on this topic is needed.

Non-sexual acts

While most HIV infections result from sex, there are many documented cases where people have gotten HIV through other pathways. Here are a few of them.

Pregnancy and breastfeeding

Most children who get HIV will get it during pregnancy, childbirth, or breastfeeding. This is known as “perinatal transmission”.

The risk will vary depending on several factors – especially if the mother is receiving effective treatment. Without any treatment, the risk of transmission during pregnancy is anywhere between 15% to 45%. However, with effective therapy, the likelihood can drop to less than 1%.

Breastfeeding can present unique challenges. If a mother is receiving antiretroviral therapy and maintains an undetectable viral load, the risk of transmission is also less than 1%. In some cases, healthcare professionals may recommend formula feeding or donor milk to eliminate the risk entirely.

Blood transfusions

Receiving a transfusion of HIV-infected blood is one of the highest-risk ways to acquire the virus. If the blood is not screened and contains active HIV, the likelihood of transmission is estimated to be over 90%—essentially, almost guaranteed. This is because the virus is directly introduced into the bloodstream in large quantities, bypassing the usual barriers like skin or mucous membranes.

However, in countries like the UK, this scenario is extremely rare thanks to rigorous screening protocols. All donated blood is tested for HIV (as well as other infections like Hepatitis B and Hepatitis C) using highly sensitive methods such as nucleic acid testing and antibody assays. These safety measures have made HIV transmission through blood transfusion virtually non-existent in modern healthcare settings.

Needles

The likelihood of HIV transmission from a contaminated needle is estimated to be around 0.3% per exposure. This means that for every 1,000 people who experience a needlestick injury involving HIV-positive blood, about three might become infected. While that may sound low, it’s still considered a significant risk, especially in healthcare settings where such exposures are more likely to occur.

While exact percentages can vary depending on the context, studies estimate the per-act risk of HIV transmission from sharing injection equipment to be around 0.63% per exposure. That’s more than double the risk from a needlestick injury in healthcare settings. The risk increases if the person with HIV has a high viral load or if the equipment is shared repeatedly.

Biting

There have only been a handful of documented cases where HIV was transmitted through biting, and even then, it involved quite extreme circumstances—deep wounds, broken skin, and the presence of blood.

For HIV to be passed on this way, there needs to be a direct route into the bloodstream, usually through significant tissue damage. So, unless there’s severe trauma involved, the risk is incredibly low.

Spitting

Spitting, on the other hand, poses no risk at all. HIV isn’t transmitted through saliva, and if the skin is intact, there’s no pathway for the virus to enter the body. This means that everyday contact doesn’t carry any real danger when it comes to HIV.

Kissing

There have been some documented cases where deep, open-mouthed kissing transmitted HIV, but this only occurred when both partners had bleeding gums or open sores in their mouths.

You can’t get HIV from closed-mouth kissing.

What are the risk factors that increase the likelihood of transmission?

Some risk factors may increase your likelihood of getting HIV.

Alcohol and drug use

Consuming alcohol or drugs will not give you HIV alone. However, these substances will impair your inhibitions and judgement, and tend to encourage behaviours that will make you more likely to contract the infection, including:

Engaging in unprotected sex
Sharing needles for drug use
Having sex with multiple partners

High viral load

Your viral load refers to how much HIV you have in your blood. Someone with a higher viral load will be more likely to pass on the virus. Antiretroviral treatment will reduce your viral load.

With effective treatment, your viral load can be lowered to undetectable levels, meaning it will be extremely unlikely that you will pass on the infection to an uninfected person.