What are sexually transmitted infections?

Sexually transmitted infections (STIs) are sometimes known as sexually transmitted diseases (STDs).

They are infectious diseases caused by bacteria, viruses and parasites that are usually spread from person to person during sexual contact. Other less common forms of transmission include from a mother to her baby during pregnancy, birth or breastfeeding, or by exposure to infected sharp objects, such as needles, and from blood and body fluid splashes.

If you have an STI, you may not necessarily experience any symptoms. This is known as being ‘asymptomatic’. Being asymptomatic is very common just after you have been exposed and, in some diseases, it can continue for some time. If you experience any symptoms, such as those listed below, you should see a doctor as soon as possible.

STIs are serious and when left untreated can have serious long-term and permanent effects on your health.