Terrence Higgins Trust uses cookies to improve your experience of our websites. For more information or to change the use of cookies, please click here.

Accept and Close

What are STIs?


Sexually transmitted infections (STIs) - sometimes called STDs (sexually transmitted diseases) - are infections you can pick up and pass on during sex. You can lower your risk by using condoms and Femidoms, having regular check-ups and limiting your exposure.

STIs can be caused by one of three things:


eg, gonorrhoeachlamydia and syphilis

Infections caused by bacteria are usually easily cured with antibiotics.


eg, HIVherpes and the liver infection hepatitis

Viruses are harder to treat but with time your body often gets rid of some viruses on its own. Other viruses such as HIV cannot be cured. You can be vaccinated against some viruses, eg, hepatitis A and B.


cause two STIs: pubic lice and scabies

Both can be caught without having sex - eg, from bedding and towels - but this isn’t common.

Symptoms of STIs:

Some STIs can cause symptoms within a few days.

Symptoms of others may not show for days, weeks or months. Sometimes you may notice no symptoms at all or mistake them for something else.

Whether you have symptoms or not, a sexual health check-up will detect any infections.

How can I stay safer?

Using a condom or Femidom cuts the chance of getting or passing on STIs - the condom or Femidom is the only type of contraception that offers any protection against them.

Condoms and Femidoms don’t take away all the risk, however, as they may not cover the part of the body where the STI is (such as a herpes sore or a syphilis rash). Also, some STIs are spread during types of sex where people are not likely to use condoms or Femidoms, eg, oral sex.

You can still get an STI if you have very few sexual partners - but the more sexual partners you have, the more likely you are to have sex with someone with an infection.

These reduce the risk of STIs being passed on:

  1. using condoms or Femidoms 
  2. having fewer partners 
  3. being checked for STIs

Next: Chlamydia ››



Whole Star Whole Star Whole Star Whole Star Whole Star (1 vote cast) Please log in or register to vote. What's this?


Please log in or register to add this article to My favourites. What's this? Adding an article to My favourites will allow you to easily come back to it later or print it.

Your comments

You will need to be logged in before you can leave a comment.

Please log in using the form on the top right of the page or register.

The Information Standard: Certified member

This article was last reviewed on 31/12/2018 by Anna Peters

Date due for the next review: 31/12/2015

Content Author: Richard Scholey

Current Owner: Health Promotion

More information:

HIV basics - Treatment - See Can HIV be cured?, NAM aidsmap, 2015

Hepatitis, NHS Choices, June 2014

Sexually transmitted infections (STIs), NHS Choices, April 2015

Chlamydia - causes, NHS Choices, August 2013

Pubic lice, NHS Choices, April 2014

Scabies, NHS Choices, August 2014

How soon do STI symptoms appear? NHS Choices, November 2014

British Association for Sexual Health and HIV Clinical Effectiveness Group, UK National Guidelines for the Management of Gonorrhoea in Adults 2011, (June 2011)

Edited by Stephen Morse et al, Atlas of Sexually Transmitted Diseases and AIDS, Third Edition, Mosby (2003)


It Starts With Me

If we all test we can stop HIV.

map with pin

Service finder

Find GU clinics and services near you.



The easiest and most effective precaution to take against most STIs is using a condom.