How is HIV spread?
Reviewed by our clinical team
Human immunodeficiency virus (HIV) is a virus that attacks the immune system. When it’s left untreated it can progress to AIDS (Acquired ImmunoDeficiency Syndrome) and leave you prone to life-threatening infections and diseases. Unfortunately, HIV cannot be cured, but it can be managed to allow you to lead a normal life. In the UK, HIV is no longer the "death sentence" it once was, when diagnosed early enough.
If you’re sexually active and concerned about HIV there are several things you can do to stay safe, including getting tested regularly. It’s also a good idea to remember how HIV is spread, so you minimise the chances of getting it.
How do you catch HIV?
HIV is spread in bodily fluids: blood, semen, vaginal secretions and anal mucus. The virus is most commonly passed from one person to another during unprotected anal or vaginal sex. Unprotected sex means sex without a condom. It can also be passed on by sharing sex toys or during oral sex.
Some people might be exposed to HIV by sharing needles or other injecting equipment when taking drugs. "Dirty" needles might also be an issue when getting a tattoo or an injection abroad. HIV-positive women can also pass on the virus to their baby during pregnancy, birth, or when breastfeeding. In the UK this risk is low: the transmission rate is les than 1% if HIV medication is taken and labour and delivery are managed well.
The virus can enter the body in a few different ways:
- Through the lining of the vagina, anus, or head of the penis
- Through the lining of the mouth
- Through open cuts and wounds on the skin
- Through a needle injection site
- Through the eyes (this is rare and doesn't really happen outside a health care setting)
Can you catch HIV from oral sex?
You can catch HIV from oral sex, but the risk is fairly low compared to penetrative vaginal or anal sex.
You’re more likely to catch HIV from oral sex if:
- You’re receiving oral sex and your partner has ulcers, bleeding gums, or any other open sores in their mouth.
- You’re giving oral sex and and you or your partner have open sores, blisters, cuts or grazes on their genitals or if they ejaculate in your mouth
- Having chlamydia, or gonorrhoea can also increase your risk of catching HIV or passing it on.
The bottom line is: use condoms even for oral sex and make sure neither you or your partner have any open sores, ulcers, blisters, cuts or bleeding gums. Get checked and treated for STIs - some STIs like chlamydia or gonorrhoea can cause inflammation which makes it easier for HIV to enter your blood stream.
Which body fluids spread HIV?
The virus is found in several different bodily fluids including:
- Vaginal fluid
- Anal mucous
- Breast milk
HIV is not carried in sweat, urine, or saliva. This is why it’s not passed on by doing any of the following:
- Being bitten
- Being spat or sneezed on
- Sharing towels or cutlery
- Using the same bath or toilet
Can HIV spread through skin-to-skin contact?
No, HIV cannot be spread through unbroken, healthy skin. However, if you have a wound or sore on your skin and this comes into contact with blood or bodily fluids from an HIV-positive person, this could lead to infection.
Can you catch HIV from period blood?
HIV is carried in blood and vaginal fluids, which means it can be transmitted through period blood.
How does HIV spread through needles?
There’s a risk of catching HIV from using needles, but only if you’re sharing them with another person. When a person with HIV uses a needle then passes it to someone else, their blood will enter the second person’s system through the injection site.
A brand new, sterile needle that hasn’t been used by anybody else won’t carry any risk of HIV transmission.
Can a person with an undetectable viral load spread HIV?
If an HIV-positive person has an undetectable viral load, they can’t pass on HIV.
An undetectable viral load usually occurs when someone has been having effective treatment for at least six months. At this point, their medication should have successfully prevented the virus from replicating in their system. This means the amount of the virus in their blood is so low it can’t be picked up in a test.
Who is most at risk of HIV?
The most likely way of getting HIV is having unprotected sex with someone who has HIV and isn't on treatment. These things increase your risk of getting HIV:
- Having unprotected sex with someone who's HIV status is unknown
- Having multiple sexual partners
- Being a man who has unprotected sex with other men
- Having rough or intense sex that causes bleeding or friction
- Having certain STIs that make it easier for HIV to enter your blood stream
- Injecting drugs and sharing injecting equipment
- Using drugs to enhance sex – this is sometimes called “chemsex”
- Getting a medical procedure, tattoo or piercing in a country that doesn’t have a good screening programme for HIV
How can I avoid getting HIV?
Using condoms and dental dams during sex is a good way to avoid HIV and other sexually transmitted infections. It’s also a good idea to use water-based lubricants as these can make sex safer by preventing condom breakage. Using lube also reduces friction- friction can cause tiny injuries through which the virus can enter the blood stream more easily. Just make sure you avoid oil-based lubes as they can weaken condom latex.
If you’re sexually active, you should get tested for HIV and other STIs fairly regularly. The Terrence Higgins Trust recommends getting tested every six months if you’re having casual sex, and every three months if you have lots of sexual partners.
You should also get an STI test whenever you notice any new symptoms, or when you start a new relationship.
If you’re particularly at-risk for HIV – for example, your partner has HIV – you could consider taking PrEP (pre-exposure prophylaxis). This is a treatment that you can take to prevent infection.
You can learn more about PrEP and where to get it at the Terrence Higgins Trust website.
If you find yourself in a situation where you’ve had unprotected sex and you think you might have been exposed to HIV, it’s important to get medical advice as soon as possible. You might be offered PEP (post-exposure prophylaxis), an emergency medication that can prevent infection when taken within 72 hours of unprotected sex.
You can learn more about PEP and where to get it at the Terrence Higgins Trust website.
Get tested for HIV with Online Doctor
If you want to get tested for HIV you can order a home test kit from Online Doctor. We use an advanced test that involves taking a small blood sample taken from your finger tip, and sending it back to our lab. Our tests can detect HIV as early as four weeks after exposure.
Find out more by visiting our online STI test clinic.