What is HIV and how is it transmitted?

HIV (human immunodeficiency virus) is a virus that attacks the body's immune system. This makes it harder for your body to fight off infections and diseases. 

The virus is most commonly passed on by bodily fluids during vaginal or anal sex without a condom.

HIV can also spread:

  • from mother to child at birth or during breastfeeding

  • by sharing needles or syringes or using unsterilised equipment for injecting

HIV cannot be transmitted in saliva, sweat or urine. 

The risk of getting HIV through oral sex is very low. It’s possible if an HIV positive person with a penis ejaculates (comes) into someone's mouth. And mouth hygiene also plays a part.

Treatment for HIV

There’s currently no cure for HIV but treatment works very well. HIV has become a manageable chronic disease. People with the virus who get diagnosed quickly and take their treatment correctly live long and healthy lives. They can expect a normal lifespan.

Once someone is on treatment that's working, and their viral load become undetectable, they won't pass on the virus. This is sometimes referred to as U=U, meaning undetectable = untransmittable.

Preventing HIV

The best way to prevent HIV infection and transmission during sex is:

  • use condoms consistently and correctly

  • test regularly and accurately.

We recommend testing every 3 months if you change partners regularly, or testing yearly if you don’t.


Written by Helen Burkitt. Senior Sexual Health and Contraception Nurse
Last updated at: 24 August 2022